-ANATOMICAL CHANGES IN TREMBLING ASPEN (POPIXLUS
TRIMULOIDES MICEX,) INDUCED BY THE APPLICATION
OE CHEMICAL AGENTS TO THE STIM

By
HAROLD JAMES RAPHAEL

A THESIS
S u b m itte d to t h e S chool o f G ra d u ate S t u d ie s o f M ichigan
S t a t e C o lle g e o f A g r i c u l t u r e and A p p lied S c ie n c e
I n p a r t i a l f u l f i l l m e n t o f t h e r e q u ir e m e n ts
f o r t h e d e g re e o f
DOCTOR OE PHILOSOPHY

D epartm ent o f F o r e s t P ro d u c ts
1954

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Ackno wl e dgme n t s

The w r i t e r w ish e s to e x p r e s s h i s s i n c e r e a p p r e c i a t i o n
to Dr, A. I . P a n s h in f o r h i s g u id a n c e and h e l p f u l c r i t i c i s m
i n t h e p r e p a r a t i o n and w r i t i n g o f t h i s p a p e r .

The a d v ic e o f

Dr. L . W. M e r i c le on t h e a n a to m ic a l p h ase o f t h i s stu d y , and
t h e a s s i s t a n c e o f Mr. M. W. Day w ith t h e f i e l d work a r e a ls o
d e e p ly a p p r e c i a t e d .
The a u th o r i s g r e a t l y in d e b te d to t h e American Boxboard
Company o f Grand R a p id s, M ich ig an , and to t h e American Ex­
c e l s i o r C o rp o ra tio n o f Chicago, I l l i n o i s , f o r p r o v i d i n g th e
fu n d s to make t h i s s tu d y p o s s i b l e .

He I s a l s o i n d e b t e d to

t h e Dow Chemical Company o f M id lan d , M ich ig an , f o r p r o v id in g
t h e c h e m ic a ls u s e d i n t h i s i n v e s t i g a t i o n .

ANATOMICAL CHANGES IN TREMBLING- ASPEN (POPDLUS
TREMULOIDES MICHX.) INDUCED BY THE APPLICATION
OE CHEMICAL AGENTS TO THE STEM

By
HAROLD I AMES RAPHAEL

AM ABSTRACT
S u b m itte d to t h e S cho ol o f G ra d u ate S t u d ie s o f M ich igan
S t a t e C o lle g e o f A g r i c u l t u r e and A p p lied S c ie n c e
i n p a r t i a l f u l f i l l m e n t o f t h e re q u ir e m e n ts
f o r t h e deg ree o f
DOCTOR OE PHILOSOPHY

Departm ent o f E o r e s t P r o d u c ts
Y ear

Approved

1954

1

ABSTRACT

The p u rp o s e o f t h i s stu d y was to o b s e rv e t h e a n a to m ic a l
changes o c c u r r i n g i n t h e stem s, r o o t s , l e a v e s , and tw ig s o f
t r e m b l i n g aspen (P o p u lu s tr e m u lo id e s M ichx.) in d u c e d by t h e
a p p l i c a t i o n o f v a r i o u s ch e m ica ls to t h e t r e e stem .

I t was

hoped t h a t t h e s e o b s e r v a t i o n s m ig h t h e lp e x p l a i n why some
c h e m ic a ls n o t o n ly h i l l t r e e s , b u t a l s o ca u se t h e b ark to
lo o sen .
The f o llo w in g c h e m ic a ls were chosen f o r t h e problem :
p r o p y le n e g ly c o l b u t y l e t h e r e s t e r o f 2 , 4 -d ic h lo ro p h e n o x y a c e t i c a c i d , p ro p y le n e g ly c o l b u t y l e t h e r e s t e r o f 2 , 4 , 5 t r i c h l o r o p h e n o x y a c e t i c a c i d , and sodium m o n o c h lo r o a c e ta te .
The e s t e r s o f 2,4-D and 2 , 4 , 5-T were a p p l i e d a s o i l s o l u ­
t i o n s by means o f a b a s a l s p ra y .

Sodium m o n o c h lo ro a c e ta te

was d i s s o l v e d i n w a te r and sp ray e d on p r e v i o u s l y made, p e e le d
g ird le s o r f r i l l g ird le s .
Seven d i f f e r e n t t r e a t i n g d a t e s were u s e d d u rin g t h e
1952 growing s e a s o n .

Stem, r o o t , and tw ig sam p les, c o n t a i n ­

i n g t h e cam bial r e g io n and a d j a c e n t t i s s u e s , were removed
from t r e e s p e r i o d i c a l l y d u rin g th e summer, from t h e f i f t e e n t h
day a f t e r t r e a t m e n t th ro u g h t h e e i g h t i e t h day.

L e a f sam ples

c o n t a i n i n g t h e m i d r i b p o r t i o n and a d ja c e n t b la d e t i s s u e s
w ere a l s o c o l l e c t e d .
I t was found t h a t a l l t h r e e ch e m ica ls caused d e a th and
p rod uced v a r y in g amounts o f bark lo o s e n i n g .

However, t h e

d eg ree o f i n j u r y to t h e cam bial r e g io n and e f f e c t i v e n e s s in

2

ABSTRACT
l o o s e n i n g t h e b a rk w ere q u i t e d i f f e r e n t .

Sodium m onochloro-

a c e t a t e , a p p l ie d to a f r i l l e d g i r d l e , was found t o be v e ry
e f f e c t i v e a s a t r e e - k i l l e r and a s a d e b a rk in g a g e n t.

The

e s t e r o f 2 ,4 , 5 - T was l e s s e f f e c t i v e , and t h e r e s u l t s w ith
2 ,4 -D were i n c o n s i s t e n t .
Stem sam ples ta k e n from t r e e s t r e a t e d w ith sodium monoc h l o r o a c e t a t e showed s e v e r e i n j u r y to m ost parenchym atous
tis s u e s .

Samples c o l l e c t e d 71 days a f t e r t r e a tm e n t showed

com plete c o l l a p s e o f t h e cam bial r e g i o n .

The l a s t - f o r m e d

c e l l s o f t h e xylem w ere i n an advanced s t a t e o f d i s i n t e g r a ­
t i o n , fo rm in g many s m a ll la c u n a e betw een xylem and cam bial
re g io n .

The phloem c o n ta in e d c o l l a p s e d and d i s i n t e g r a t e d

parench ym ato us t i s s u e th ro u g h o u t t h e r e g i o n .

The o n ly phloem

c e l l s l e f t i n t a c t were f i b e r s and s c l e r e i d s .

These c e l l s

w ere o f t e n l e f t i n i s o l a t e d g ro u p s due to com plete d i s i n t e ­
g r a t i o n o f s u rro u n d in g parench ym atou s t i s s u e .
Stem sam ples ta k e n 71 days a f t e r tr e a tm e n t from 2,4-D
and 2 , 4 , 5-T t r e a t e d t r e e s showed com plete c o l l a p s e o f th e
cam bial r e g io n , b u t t h e d e g re e o f i n j u r y to t h e xylem and
phloem was much l e s s th a n i n t r e e s t r e a t e d w ith sodium monoch lo ro ac e t a t e .
I t was co n c lu d e d t h a t b ark lo o s e n in g i s caused by a
c o m b in atio n o f chem ical and p h y s i c a l changes o c c u r r i n g in
t h e cam bial r e g i o n o f t h e stem .

C o lla p se o f new ly-form ed

xylem c e l l s and accompanying la c u n a e , i n c o n ju n c tio n w ith

5

ABSTRACT
c o l l a p s e and d i s i n t e g r a t i o n o f cam b ial and a d j a c e n t phloem

c e l l s , e v i d e n t l y r e s u l t s i n t h e f o r m a tio n o f a b e l t o f weak­
ened m a t e r i a l ,

c o n s i s t i n g o f rem n ants o f c e l l w a ll s and c e l l

c o n t e n t s t h a t can be r u p t u r e d e a s ily *

C o lla p se o f c e l l s ap­

p a r e n t l y i s c a u se d , a t l e a s t i n p a r t , by a c o n t r a c t i o n o f
m

t h e e n t i r e phloem re g io n *

T h is c o n t r a c t i o n i s r e s t r a i n e d by

t h e xylem, c a u s in g lo n g v e r t i c a l s p l i t s to o c c u r i n t h e b ark
o f many t r e e s a f t e r tre a tm e n t*

TABLE OF CONTENTS
PAGE
LIST OF TABLES......................................................................................

vi

LIST OF F I G U R E S ........................................................................
I.

PURPOSE AND SCOPE OF PROBLEM .

v ii

...............................

1

II.

INTRODUCTION.....................................................................

4

III.

REVIEW OF LITERATURE...................................................

8

A. H i s t o r i c a l Development o f T ree P o is o n in g

. .

8

B. Development o f Chemical D ebarking i n
C a n a d a ..........................................................................

16

C. Chemical D ebarking i n t h e U n ite d S t a t e s . . .

23

D* The P e r i o d i c i t y o f Secondary Growth and t h e
R e l a t e d Changes O c c u rrin g i n t h e Cambium
and A d ja c e n t T is s u e s o f Woody P l a n t s . . . .

29

E. V a rio u s R esponses o f Some P l a n t s When
T r e a t e d With C hem icals

.

....................................

33

IV.

EXPERIMENTAL PROCEDURE...............................................

40

V.

FIELD OBSERVATIONS........................................................

70

VI.

LABORATORY DATA ON THE ANATOMY OF STEMS, TWIGS,
LEAVES, AND ROOTS—WITH APPLICABLE FIELD OB­
SERVATIONS .................................................................................

94

A. Stem Anatomy o f U n t r e a te d T r e e s .................. .... .

94

1 . D e s c r i p t i o n o f th e Cambial Region and
A d ja c e n t T is s u e s o f t h e S t e m ....................

94

iv
PAGE
2. C o n d itio n o f th e Cambial R egion and
A d ja c e n t T i s s u e s o f t h e Stem a t D if­
f e r e n t Times o f t h e Y e a r .....................................

96

B. P r o g r e s s i v e E f f e c t s o f Chemicals on t h e
Stem Anatomy o f T rees T r e a te d During 1952 . .

99

1 . E f f e c t s o f Sodium M o n o c h lo ro a c e ta te on t h e
Cambial Region and A d ja c e n t T is s u e s

. . .

99

2. E f f e c t s o f 2 ,4 , 5-T E s t e r on t h e Cambial
Region and A d ja c e n t T i s s u e s ...........................

106

3. E f f e c t s o f 2,4-D E s t e r on t h e Cambial
Region and A d jac en t T is s u e s

. . . . . . . .

112

C. A ppearance o f t h e Cambial R egion and A d ja c e n t
Stem T is s u e s R e s u l t i n g from Chemical T r e a t­
m en ts A pplied on D i f f e r e n t D a t e s .......................

116

1 . The A ppearance o f Stem T is s u e s Taken from
T re e s T re a te d on D i f f e r e n t D ates w ith
Sodium M o n o c h lo ro a c e ta te In P r i l l s . . . .

117

2 . The A ppearance o f Stem T is s u e s Taken from
T rees T r e a te d on D i f f e r e n t Dates w ith a
B asal S p ray o f 2 ,4 , 5-T E s t e r ...........................

119

3 . The A ppearance o f Stem T is s u e s Taken from
T re es T re a te d on D i f f e r e n t D ates w ith
2 ,4 -D E s t e r A p p lie d as a B asal S pray . . .

121

V

PAGE
D. The E f f e c t s o f 2 , 4 , 5-T E s t e r a t D i f f e r e n t
H e ig h ts i n t h e Tree S t e m .........................................
E. M is c e lla n e o u s O b s e r v a tio n s

. .................................

125
126

1 . The E f f e c t s o f Doubling t h e C o n c e n tra tio n
o f 2 ,4 , 5-T E s t e r ......................................................
2. The E f f e c t s o f C hem icals on Twigs

. . . .

126
127

3. The E f f e c t s o f Chemical T reatm ent on
L e a v e s .............................................................................

128

4. The E f f e c t s o f Chemical T re atm e n ts on th e
Main R oots
V II.

....................................

130

DISCUSSION AND CONCLUSIONS.............................................

172

A. D i s c u s s i o n ........................................................................

172

1 . E i e l d O b s e r v a t i o n s .................................................

17 2

2. A natom ical Changes i n t h e T is s u e s o f
Stems, Twigs, L e a v e s, and R o o t s ..................

17 6

B. C o n c l u s i o n s ........................................................................

185

BIBLIOGRAPHY

187

LIST OF TABLES
TABLE
I.

PAGE
S ch edule o f T re a tm e n ts Made a t Dunbar D uring
195 2 .................................................................................................. 45-46

II.

S chedu le o f T re a tm e n ts Made a t J e n n is o n D uring
195 3 ...............................................................................................

III.

47

S ch ed u le o f Stem Samples Taken from T re es
T re a te d w ith T hree D i f f e r e n t Chemicals and Col­
l e c t e d a t A pp ro x im ately Weekly I n t e r v a l s D uring
t h e Summer o f 1952 ...............................................................

IV.

C o l l e c t i o n S ch ed u le o f

50-51

Stem Samples Taken 36

Days a f t e r T r e a t i n g , from T re e s Which Had Been
T re a te d on V a rio u s D ates During 1952 .......................

53

V. C o l l e c t i o n S ch ed u le o f A ll Samples Taken a t
Dunbar During 19 52 and t h e J e n n is o n A rea D uring
1953 and 1954
VI.

55-57

Summary o f I n s p e c t i o n Made on Septem ber 5, 1952,
o f Aspen T re a te d During 1952 ......................................... 7 6-77

V II .

Summary o f I n s p e c t i o n Made on June 13, 1953, o f
Aspen T re a te d During 1952

79-80

LIST OF FIGURES
FIGURE

PAGE

1 . , Showing Method o f Removing O u te r Bark o f a Tree
w ith a C h i s e l ...........................
2.

61

F o rm ation o f R e c ta n g le by C u ttin g th ro u g h t h e
Phloem and i n t o t h e O u te r L a y e rs o f t h e X ylan . .

3.

F o rm atio n o f O ctagon by C u ttin g a c r o s s t h e Cor­
n e r s o f P r e v i o u s l y Formed R e c ta n g le .

4.

.....................

67

Aspen Tree, T r e a te d w ith 2 , 4 , 5-T E s t e r , Showing
Complete D e f o l i a t i o n 45 Daysa f t e r T reatm en t

6.

65

Method o f P r y i n g Out Sample Composed o f Phloem,
Cambium, and O u term o st R ings o f X y l e m ........................

5.

63

. .

87

Stem o f Aspen T re a te d w ith 2 ,4 , 5-T E s t e r Showing
R ings o f B lack en ed Xylem T is s u e R e s u l t in g from
T r e a t m e n t ......................................................................................

7.

87

Stem o f Aspen T re a te d w ith 2,4-D E s t e r , Showing
E x u d atio n o f R esin o u s F l u i d from D is c o lo re d
S p o t s ...............................................................................................

8.

89

Branch o f Aspen Tree T r e a te d w ith 2 ,4 , 5-T E s t e r ,
Showing T y p ic a l V a r ie g a te d C olor Found 80 Days
a f t e r T r e a t m e n t ........................................................................

9.

89

Base o f Tree T r e a te d w ith 2 , 4 , 5-T E s t e r , Showing
S p l i t t i n g and D i s c o l o r a t i o n o f Bark One Y ear
A f t e r T r e a t m e n t ...........................

91

_

•

•

•

V I11

FIGURE
10.

PAGE

U pper P o r t i o n o f Aspen T ree T re a te d w ith 2 , 4 , 5-T
E s t e r , Showing S p l i t t i n g o f Stem Bark One Y ear
a f t e r T r e a t i n g ...............................

11.

91

Aspen T ree T re a te d w ith Sodium Mono ch lo ro a c e t a t e ,
Showing D i s c o l o r a t i o n o f Phloem above T r e a te d
H a l f o f Stem, and Showing H e a lth y T is s u e above
U n tr e a te d H a l f o f S t e m .........................................................

12.

Base o f T ree T re a te d w ith Sodium M ono c h lo ro a c e t a t e ,
Showing E vidence o f W i l d l i f e A c t i v i t y . . . . . .

13.

93

93

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and A dja­
c e n t T is s u e s o f an Aspen Stem, Showing P ro m in en t
S ie v e Tubes and S ie v e P l a t e s w ith C a llo s e . . . .

14.

R a d ia l S e c t i o n o f th e Cambial Region and A d jacen t
T is s u e s o f an Aspen S t e m ..................................................

15.

133

133

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and. A dja­
c e n t T is s u e s o f an Aspen Stem Showing S t a r t o f
Phloem and Cambial A c t i v i t y ..........................

16 .

135

T r a n s v e rs e S e c tio n o f t h e Cambial Region and A dja­
c e n t T is s u e s o f an Aspen Stem.

Cambium i s i n

T y p ic a l Dormant C o n d itio n , C h a r a c te r iz e d by Firm
W alls and R e c ta n g u la r C ell Shape
17.

.......................

135

T ra n s v e rs e S e c tio n o f t h e Cambial Region and Adja­
c e n t T is s u e s o f an Aspen Stem, Showing A c t i v e l y
D iv id in g Cambium, Expanding S ie v e Tubes, and UewlyEormed Xylem C e l l s w ith Thin W alls

.......................

137

PAGE

FIGURE
18.

T r a n s v e r s e S e c tio n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing Dark,
G ra n u la r C e ll C o n te n ts , Harrow Cambial R egion,
and Heavy C a llo s e F o rm atio n s

19.

.........................................

157

T ra n s v e rs e S e c t i o n o f th e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing D i s t o r t e d
C e lls i n t h e Cambium, Absence o f E x tru d ed N u c le o li,
and Very T hick, Dark C e ll W alls i n t h e Phloem . .

20.

T r a n s v e r s e S e c tio n o f t h e Phloem, A d ja c e n t to t h e
Cambial R egion, Showing Thick C e ll W a lls

21.

139

. . . .

139

T ra n s v e rs e S e c tio n o f t h e Cambial R egion and Ad­
j a c e n t T is s u e s o f an Aspen Stem.

N ote L a rg e , Ex­

panded S ie v e Tubes, Ytfell D efined S ie v e P l a t e s
w ith C onnecting S t r a n d s , and E x tru d ed N u c le o li
22.

141

T r a n s v e r s e S e c t io n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing S ev ere
C o lla p s e i n t h e Cambium and A d ja c e n t T is s u e s ,
B lackened Ray C e l l s , and Void A reas i n th e
P h l o e m ..........................................................................................

25.

141

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing B lack­
ened, D i s t o r t e d T is s u e o f th e Cambial Region

24.

. .

143

.................................................................................

143

R a d ia l S e c tio n o f Cambium and phloem o f an
Aspen Stem

PAGE

FIGURE
25.

T r a n s v e rs e S e c tio n o f t h e Cambial R egion and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing I n t a c t
Cambial R egion and Xylem; Some P arenchym atous
C e l l s o f t h e Phloem Have T hickened W alls

26.

. . . .

145

T r a n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing E a r ly
S ta g e s o f C o lla p s e i n t h e Cambium, and T hickW alled Parenchym atous C e lls i n t h e Phloem . . . .

27.

14-5

T ra n s v e rs e S e c tio n o f t h e Cambial R egion and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing D e t a i l s
o f T hickened W alls and C o lla p se d C e l l s i n th e
P h l o e m ...................................................... .... ...............................

28.

147

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f t h e Stem o f an Aspen, Showing
Advanced S t a t e o f C o lla p se i n t h e Cambium and Ad­
j a c e n t Phloem T is s u e s ; P arenchym atous C e lls i n
Xylem Have B lack en ed C ell C o n t e n t s ...........................

29.

147

R a d ia l S e c tio n o f t h e Cambial Region and A d ja c e n t
T is s u e s o f t h e Stem o f Aspen, Showing B lackened
C e ll W alls and C o n te n ts i n t h e V i c i n i t y o f t h e
C am bium ..........................................................................................

30.

149

T ra n s v e rs e S e c t io n o f t h e Cambial Region and A dja­
c e n t T is s u e o f an Aspen Stem, Showing Advanced Dis
i n t e g r a t i o n o f Cambium, and Thickened W alls o f
P arenchym atous C e lls i n t h e P h l o e m ...........................

149

FIGURE;
51.

PAGE

T r a n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing B lack ­
ened C e ll W alls o f t h e Cambial R egion

and T hick ,

B lackened W a lls i n t h e P h l o e m ............................................
52.

151

T r a n s v e r s e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e o f an Aspen Stem, Showing Numerous
E x tru d ed N u c l e o l i , P ro m in en t S ie v e P l a t e s , and
C e l l s R ich i n C o n t e n t s ..........................................................

55*

151

T r a n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing B lack ­
ened C ell C o n te n ts o f Cambium and Phloem, Thick
W a lls i n t h e Phloem , and C o lla p s e o f Cambial
C e l l s ...................................................... ; ...................................

34.

153

Phloem o f F ig u re 33 a t H ig h e r M a g n i f ic a ti o n ,
Showing T hickened W alls, and Absence o f S ie v e
P l a t e s and E x tru d e d N u c l e o li i n

35.

S ie v e Tubes . , .

153

T ra n s v e rs e S e c tio n o f t h e Phloem, Im m ed iately Ad­
j a c e n t to t h e Cambial R egion, Showing Expanded
S ie v e Tubes w ith P ro m in e n t S ie v e P l a t e s . . . . .

36.

155

T r a n s v e rs e S e c tio n o f t h e Cambial Region and A dja­
c e n t T i s s u e s o f an Aspen Stem, Showing E a r ly
S t a g e s o f C o lla p s e i n t h e Cambial R egion, B lackened
Phloem and Xylem Ray T is s u e , and D i s i n t e g r a t i o n o f
Phloem C e l l s A d ja c e n t to t h e Cambium

. . . . . .

155

x ii
FIGURE
57.

PAGE

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing I n t a c t
C e ll W alls i n t h e Cambium and Xylem, and E a r ly
S ta g e s o f C o lla p s e i n t h e P h l o e m ................................

5 8.

157

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing No E v i­
dence o f Damage from Chemical T r e a t m e n t ..................

59.

157

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f an Aspen Stem, Showing C o lla p s e
o f Cambium and Phloem Parenchyma C e lls A d ja c e n t
to Cambium

40.

. . . . .

...........................................................

159

T ra n s v e rs e S e c t i o n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f t h e Stem o f an Aspen.

C o n d itio n

o f t h i s S e c tio n i s Comparable to That o f F i g ­
u r e 5 9 ........................................................................ ....
41.

159

T ra n s v e rs e S e c tio n o f t h e Cambial Region and Ad­
j a c e n t T is s u e s o f t h e Stem o f an Aspen.

Cambium

and Xylem a r e I n t a c t ; E a r ly S ta g e s o f C o lla p s e and
Some Wall T h ic k e n in g V i s i b l e i n P h l o e m ..................
42*

161

T ra n s v e rs e S e c t io n o f t h e Tip o f t h e L e a d e r o f an
Aspen Stem, Showing Com pletely B lackened and Col­
l a p s e d Cambium

43.

....................................................................

T ra n s v e rs e S e c t io n o f t h e Cambial Region and A dja­
c e n t T is s u e s o f an Aspen Stem, Showing Advanced
S ta g e o f D i s i n t e g r a t i o n o f Cambial C e l l s , Lacunae

161

x iii
FIGURE

PAGE

Between Xylem and Cambium, an d jT h ick Parenchym a
W alls i n t h e P h l o e m ................................................................
44.

T r a n s v e r s e S e c t i o n o f a Twig from an U n t r e a t e d
T r e e ...............................................................................................

45.

T r a n s v e r s e S e c t io n o f a Twig from
w ith 2 ,4 , 5-T E s t e r on J u l y 9

46.

163

165

a Tree T r e a te d

..........................................

T r a n s v e r s e S e c tio n o f t h e M id rib P o r t i o n

165

o f an

Aspen L e a f, Showing V a s c u la r B undle, Bundle
S h e a th , and S u rro u n d in g C e l l s .........................................
47.

T ra n s v e rs e S e c t i o n o f t h e L e a f B lade Im m ed iately
A d ja c e n t to t h e M id rib S e c tio n o f F ig u re 46 . . .

48.

T ra n s v e rs e S e c t io n o f t h e M id rib o f a L e a f .
an Aspen Tree T r e a te d w ith 2,4-D E s t e r

49.

167

From

. . . . .

169

P o r t i o n o f L e a f B lade A d ja c e n t to t h e M id rib De­
s c r i b e d in F ig u re 48

50.

166

169

T ra n s v e rs e S e c tio n o f th e Cambial R egion and Ad­
j a c e n t T is s u e s o f an Aspen R oot, Showing E x tru d ed
N u c l e o l i , Expanded S ie v e Tubes, and P rom in ent
S ie v e P l a t e s .............................................................................

51.

T ra n s v e rs e S e c tio n o f t h e Cambial

171

Region and Adja­

c e n t T is s u e s o f an Aspen R oot, Showing C o n tra c te d
A ppearance o f S ie v e Tubes, Absence o f E xtruded Nu­
c l e o l i , and Lack o f V i s i b l e S ie v e P l a t e s

. . . .

171

I.

PURPOSE AND SCOPE OF PROELM

The p u rp o se o f t h i s stu d y was to o b s e rv e t h e a n a to m ic a l
ch an ges o c c u r r i n g i n t h e ste m s , r o o t s , l e a v e s , and tw ig s o f
tre m b lin g asp e n (P o p u lu s tr e m u l o i d e s M i c h x . ) , a f t e r t h e ap­
p l i c a t i o n o f v a r i o u s c h e m ic a ls t o t h e stem s o f t h e t r e e s .
O b s e r v a tio n s were made on t h e cam b ial re g io n and a d j a ­
c e n t t i s s u e s o f t h e ste m s, r o o t s , and l e a v e s .

E x am in atio n s

were a ls o c a r r i e d o u t on t h e m id r ib p o r t i o n o f t h e l e a v e s .
V a rio u s i n v e s t i g a t o r s h ad o b s e rv e d t h a t c e r t a i n chem­
i c a l s n o t o n ly k i l l e d t r e e s b u t a l s o caused t h e b ark to p e e l
o f f re a d ily ,
n a te d .

even a f t e r t h e norm al s a p - p e e l i n g seaso n t e r m i ­

A c c o rd in g ly , t h r e e c h e m ic a ls which had been r e p o r t e d

a s h a v in g a l o o s e n i n g e f f e c t on b ark were s e l e c t e d f o r t h i s
stu d y .

I t was r e a s o n e d t h a t t h e o b s e r v a t io n o f a n a to m ic a l

changes o c c u r r i n g w i t h i n a t r e e m ig h t h e l p e x p l a in how t h e s e
ch e m ica ls caused t h e s e p a r a t i o n o f b a rk from t h e t r e e stem .
The f o llo w in g c h e m ic a ls were chosen f o r t h e problem :
p ro p y le n e g l y c o l b u t y l e t h e r e s t e r o f 2 ,4 -d ic h lo ro p h e n o x y a c e t i c a c i d , p r o p y le n e g l y c o l b u t y l e t h e r e s t e r o f 2 , 4 , 5 tr ic h lo r o p h e n o x y a c f e tic a c i d , and sodium mono c h lo ro a c e t a t e .
The f i r s t two c h e m ic a ls a r e commonly r e f e r r e d to a s 2 ,4 -D
e s t e r and 2 , 4 , 5-T e s t e r , r e s p e c t i v e l y .

F o r t h e sake o f

b r e v i t y , t h e a b b r e v i a t i o n s a r e u se d i n t h i s p a p e r .

2

I n v iew o f t h e f a c t t h a t b a r k - f r e e wood i s v e r y im por­
t a n t to t h e p u lp and p a p e r i n d u s t r y , and b e c a u se t h e t r u n k
o f t h e t r e e i s u s u a l l y t h e o n ly p o r t i o n u s e d i n t h e m anufac­
t u r e o f p u lp , t h e m a jo r em phasis o f t h i s s tu d y was p l a c e d on
t h e anatomy o f t h e cam bial r e g io n and a d j a c e n t t i s s u e s o f
t h e stem .

O b s e r v a tio n s on t h e anatomy o f l e a v e s , t w i g s , and

r o o t s were made i n o r d e r to o b t a i n a d d i t i o n a l in f o r m a t i o n on
t h e e f f e c t s o f t h e chem icals*
I n a d d i t i o n to c o l l e c t i n g d a t a on t h e m e c h a n ic s o f b a rk
s e p a r a t i o n , i t was hoped to d e te rm in e which o f t h e c h e m ic a ls
u s e d was t h e m o st e f f e c t i v e i n lo o s e n in g t h e bark o f a s p e n .
D i f f e r e n t c o n c e n t r a t i o n s o f c h e m ic a ls were employed In o r d e r
to s tu d y t h e e f f e c t o f s t r e n g t h o f s o l u t i o n .

M ethods and

d a t e s o f t r e a t i n g were v a r i e d i n an a tte m p t to e s t a b l i s h op­
timum c o n d i t i o n s f o r t r e a t i n g aspen .
F i e l d o b s e r v a t i o n s w ere made i n an a tte m p t to c o r r e l a t e
e x t e r n a l changes i n t h e t r e e w ith i n t e r n a l a n a to m ic a l
c h a n g es.

These o b s e r v a t i o n s were made on l e a v e s , b ra n c h e s ,

stem s, and r o o t s o f t r e a t e d t r e e s .

P e rio d ic in sp e c tio n s o f

a l l t r e a t e d t r e e s w ere made to check t h e e f f e c t i v e n e s s o f
t h e v a r io u s ch em ical t r e a t m e n t s .
The problem was l i m i t e d t o tre m b lin g a sp e n b e c a u se o f
t h e abundance o f t h i s s p e c i e s i n t h e Lake S t a t e s and b e c a u s e
o f t h e r e c e n t i n c r e a s e d u s e o f t h i s t r e e by t h e p u lp and
p a p e r i n d u s t r y a s a s o u r c e o f raw m a t e r i a l .

3
I n 1942 t h e m ost im p o rta n t pulpwood s p e c i e s i n t h e L ake
S t a t e s from t h e s t a n d p o i n t o f amount c u t was sp ru c e ; i n t h a t
y e a r a p p r o x im a te ly 426,000 s t a n d a r d c o r d s , rough wood "basis,
were c u t .

The amount o f asp en c u t was a p p r o x im a te ly 322,000

cords.

The amount o f aspen h a r v e s t e d i n 1951 was 935,000

cords.

The n e x t h i g h e s t s p e c i e s i n 1951 was p i n e w ith a t o ­

t a l o f 544,000 c o rd s b e in g c u t ( 3 8 ) .

I n 1953, asp en c o n t i n ­

ued to l e a d o t h e r s p e c ie s w i t h a t o t a l o f 9 38,90 2 co rd s h a r ­
v e ste d .

T h is r e p r e s e n t e d ab o u t 45 p e r c e n t o f th e t o t a l

pulpwood h a r v e s t i n t h e Lake S t a t e s ( 3 9 ).

II.

INTRODUCTION

I n t h e m a n u fa c tu re o f p u lp and p a p e r , i t i s i m p e r a t i v e
t h a t a l l h ark he removed from t h e pulpwDod s t i c k b e f o r e t h e
l a t t e r i s p ro cessed .

P a r t i c l e s o f b ark a r e o b j e c t i o n a b l e

b ec au se th e y a r e n o t re d u c e d to p u lp and show up i n t h e f i n ­
i s h e d p a p e r as s p e c k s .

Bark o f m ost t r e e s n o t o n ly p o s s e s s ­

es l i t t l e o r no f i b e r v a l u e , b u t c o n t a i n s d i r t and o t h e r im­
p u r i t i e s which m u st be removed b e f o r e t h e f i n a l p ro d u c t i s
form ed.

Mien chem ical p u lp in g m ethods a r e u s e d , b ark con­

sumes c h e m ic a ls and steam to no u s e f u l p u r p o s e .

In ad d itio n ,

i t o c c u p ie s v a l u a b l e d i g e s t o r sp ac e t h a t c o u ld be u t i l i z e d
by a d d i t i o n a l wood c h i p s .

F o r t h e s e r e a s o n s pulpwood m ust

b e c o m p le te ly b a rk e d e i t h e r i n t h e woods o r j u s t p r i o r t o
t h e p u lp in g o p e r a t i o n a t t h e m i l l .
Many m i l l s p r e f e r pulpwood t h a t has' been h a n d - p e e le d
i n t h e woods b e c a u se s h ip p in g such wood u s u a l l y r e s u l t s i n
g r e a t l y re d u c e d t r a n s p o r t a t i o n c h a rg e s .

More a c t u a l wood

s u b s ta n c e can be t r a n s p o r t e d f o r l e s s money b ec a u se o f t h e
u t i l i z a t i o n o f sp ac e t h a t o th e r w is e would be o c c u p ie d by th e
b a rk , and b e c a u se o f t h e s a v in g In w eig ht due to rem oval o f
th e b a r k .
I n t h e u p p e r p e n i n s u l a o f M ich ig an pulpwood i s sh ip p e d
by r a i l a c c o rd in g to a w eig h t agreem ent betw een r a i l r o a d and

5
sh ip p e r.

F o r aspen t h e a g re e d w e ig h t f o r a s ta n d a r d c o rd o f

rough (u n p eeled ) wood i s 4,300 pounds; t h e a g r e e d w e ig h t f o r
a s t a n d a r d c o rd o f p e e le d wood i s 3,000 p o u n d s.

A ll f r e i g h t

c h a rg e s a r e b a se d on t h e s e w e i g h t s . /
H an d -p e e le d wood i s a ls o l e s s w a s t e f u l o f raw m a t e r i a l
t h a n m e c h a n ic a lly b a rk e d wood.

Most m e c h a n ic a l b a r k e r s r e ­

move a c e r t a i n amount o f wood i n t h e p r o c e s s o f removing t h e
bark.

Hand p e e l i n g , on t h e o t h e r hand, removes l i t t l e , i f

any, wood.
Pulpwood p e e le d i n t h e woods e l i m i n a t e s t h e b a rk d i s ­
p o s a l problem t h a t c o n f r o n t s m i l l s Tfiiiich p e e l w ith some ty p e
o f m e c h a n ic a l b a r k e r a t t h e m i l l .

A ltho ugh much r e s e a r c h

h a s been con ducted to f i n d u s e s f o r t h e b a rk , i n m o st i n ­
s ta n c e s i t can o n ly be u s e d f o r f u e l o r m ust be d is p o s e d o f
by o t h e r m eans.

Even when u s e d a s f u e l i t m ust be p r e s s e d ,

d r i e d , s t o r e d , and b u rn e d i n s p e c i a l o v en s i f maximum e f f i ­
c ie n c y i s to b e o b t a i n e d { 6 4 ).

l i i i s p r o c e s s i n v o l v e s a con­

s i d e r a b l e o u t l a y o f money f o r equipm ent and demands a d d i ­
t i o n a l sp ace f o r l a r g e s t o r a g e b i n s .
I n o r d e r to remove b a rk by h a n d - p e e lin g m ethods i t i s
n e c e s s a r y to c u t and p e e l t r e e s d u rin g t h e s o - c a l l e d sa p p e e lin g season.

F o r aspen, i n t h e Lake S t a t e s , t h i s seaso n

e x te n d s from a b o u t t h e m id d le o f May u n t i l t h e end o f A ug ust,
depending on l o c a t i o n and t e m p e r a tu r e .
During t h e s a p - p e e l i n g s e a so n , f o r r e a s o n s to be ex­
p l a i n e d l a t e r , t h e r e e x i s t s i n t h e cam bial zone o f t h e t r e e

6
t r u n k , a p la n e o f w eakness which a llo w s t h e h a rk to he
p e e le d o f f e a s i l y .

B e fo re and a f t e r t h i s se a so n t h e h a rk i s

h e l d v e ry t i g h t l y to t h e stem o f t h e t r e e and i s d i f f i c u l t
to remove.
One o f t h e m ost s e r i o u s p ro b lem s c o n n e c te d w ith hand
p e e l i n g to d ay i s t h e s c a r c i t y o f woods l a b o r .

I t is v irtu ­

a l l y im p o s s ib le f o r p u lp m i l l s to o b t a i n enough h a n d - p e e le d
pulpwood d u rin g t h e s a p - p e e l i n g se a so n to s a t i s f y t h e i r
needs f o r th e y e a r.

I t i s a l s o im p o s s ib le to h i r e woods l a ­

b o r o u t s i d e t h e s a p - p e e l i n g sea so n i f th e y a r e to be p a i d on
a p i e c e b a s i s b e c a u s e o f t h e low p r o d u c tio n r e s u l t i n g from
t h e d i f f i c u l t i e s e n c o u n te re d i n removing t i g h t b a r k .

L ik e ­

w is e , i t would n o t be econom ical to h i r e l a b o r by t h e h o u r
f o r t h i s ty p e o f work.
M ec h an ical b a r k in g i s p r e f e r r e d by some d e s p i t e t h e ad­
v a n ta g e s c i t e d f o r h a n d - p e e le d pulpwood.

Pulpwood p e e le d I n

t h e woods f r e q u e n t l y becomes imbedded w ith d i r t and g r i t enr o u t e to t h e m i l l and m ust be th o r o u g h ly c le a n e d b e f o r e u s ­
in g .

I f t r a n s p o r t a t i o n d i s t a n c e s a r e s h o r t , o r i f t h e wood

can be d r iv e n down r i v e r s o r stre a m s , t h e sa v in g s e f f e c t e d
by p e e l i n g i n t h e woods may n o t be v e ry g r e a t .

I f an ade­

q u a te su p p ly o f h a n d - p e e le d wood i s n o t a v a i l a b l e , m e c h a n ic a l
b a r k e r s w i l l have to be m a in ta in e d to meet t h e b a la n c e o f
t h e r e q u ir e m e n ts .

7
Even when m e c h a n ic a l b a r k e r s a r e u s e d , th e y a r e m ost
e f f i c i e n t when t h e pulpwood h a s been c u t and sh ip p e d d u rin g
t h e s a p - p e e l i n g season*

Wood t h a t h a s been c u t b e f o r e o r

a f t e r t h e s a p - p e e l i n g se a so n , o r wood t h a t h a s been c u t d u r­
in g t h i s se a so n and n o t p e e le d q u i c k l y , w i l l h ave t i g h t
bark.

These s t i c k s f r e q u e n t l y m ust be s e n t th ro u g h t y p i c a l

drum b a r k e r s t h r e e o r f o u r tim e s i n o r d e r to remove a l l t h e
bark.

I f c u t and b a r k e d d u rin g t h e s a p - p e e l i n g s e a s o n , m ost

s t i c k s w i l l b a rk c l e a n l y w ith one o r a t t h e m ost two t r i p s
th ro u g h t h e b a r k e r .
I n o r d e r to e l i m i n a t e some o f t h e s e p ro b le m s, much r e ­
s e a r c h has been co ndu cted i n an e f f o r t to f i n d m ethods o f
t r e a t i n g t r e e s w ith c h e m ic a ls which would k i l l t h e t r e e s
d u rin g t h e s a p - p e e l i n g sea so n and m a i n t a i n t h e b a rk i n a
lo o s e n e d c o n d i t i o n f o r an i n d e f i n i t e p e r i o d o f tim e .

In

t h i s way pulpwood c o u ld be h a r v e s t e d and p e e l e d e i t h e r by
hand o r by m e c h a n ic a l b a r k e r s a t any s e a s o n o f t h e y e a r ,
e l i m i n a t i n g t h e p rob lem s o f s c a r c i t y o f woods l a b o r and ex­
c e s s i v e t r i p s th ro u g h b a r k e r s .

T h is would h e l p i n s u r e an

a d e q u a te , c o n tin u o u s su p p ly o f pulpwood w hich could be
p e e le d a t low c o s t due to t h e ea se o f p e e l i n g .

III.

REVIEW OE LITERATURE

A, H i s t o r i c a l Development o f T ree P o is o n in g
The u s e o f c h e m ic a ls f o r t h e p u rp o s e o f k i l l i n g unde­
s i r a b l e t r e e s and s h ru b s i s n o t a new i d e a .

A u stra lia n f o r ­

e s t e r s employed v a r i o u s s o l u t i o n s c o n t a i n i n g a r s e n i c a s a
s i l v i c u l t u r a l t o o l a s e a r l y as 1917 ( 4 5 ).
E a r ly e x p e rim e n ts i n t h e U n ite d S t a t e s c o n c e rn in g t h e
t r e a tm e n t o f t r e e s w i th c h e m ic a ls w ere made by R u d o lfs i n
1919 ( 5 9 ) .

He co n d u c te d e x p e rim e n ts to d e te rm in e t h e p h y s i ­

o l o g i c a l changes t h a t o c c u r r e d i n l i v i n g t r e e s when th e y
w ere t r e a t e d w ith sodium c h l o r i d e .

One o f h i s m ost i n t e r ­

e s t i n g o b s e r v a t i o n s was t h e ga?eat v a r i a t i o n i n r e a c t i o n
among d i f f e r e n t s p e c i e s and i n d i v i d u a l s w i t h i n a s p e c i e s .
He found t h a t c e r t a i n s p e c i e s showed v ig o r o u s grow th a f t e r
an a p p l i c a t i o n o f 7 pounds o f s a l t p e r t r e e w h ile o t h e r s
showed e x t e n s i v e i n j u r y w ith an a p p l i c a t i o n o f o n ly 4
pounds.

The d e g re e o f grow th and i n j u r y a l s o v a r i e d w id e ly

among i n d i v i d u a l s w i t h i n a s p e c i e s .
H e r b e r t (37) r e p o r t e d t h e u s e o f a r s e n i c a s a t r e e
k i l l e r i n 1925.

A s o l u t i o n o f 1 pound a r s e n i c and 1 pound

washing soda, d i s s o l v e d i n 4 g a l l o n s o f w a te r gave v e r y good
r e s u l t s i n k i l l i n g c e r t a i n b r o a d le a v e d t r e e s and p r e v e n te d
sp ro u tin g .

9
The U n ite d £ t a t e s D epartm ent o f A g r i c u l t u r e co n d u c te d
l a r g e s c a l e t e s t s w i t h sodium a r s e n i t e a s a t r e e p o is o n and
p u b l i s h e d t h e r e s u l t s i n 1928 (12) .

The p u rp o s e o f t h e s e

t e s t s was to d e te rm in e i f t r e e p o is o n in g was an e f f e c t i v e
m ethod o f c l e a r i n g l a n d and h a s t e n i n g decay o f stum ps and
lo g s.

I t was r e p o r t e d t h a t w i t h i n one y e a r a f t e r t r e a t m e n t ,

s e v e n ty - s e v e n o f 208 p o is o n e d t r e e s had f a l l e n .

The wood i n

t h e s e t r e e s was d i s c o l o r e d , s o f t and spongy and h ad no v a l u e
f o r lu m b e r.

Most o f t h e re m a in in g t r e e s were d ead , alth o u g h

s t i l l sta n d in g .

A v e r y c o n c e n t r a t e d s o l u t i o n o f 1 pound

w h ite powdered a r s e n i c and 2 pounds o f l y e , m ixed i n 2 g a l ­
l o n s o f w a te r , was u s e d to t r e a t 30 t r e e s h a v in g an a v e ra g e
d ia m e te r o f 15 I n c h e s a t b r e a s t h e i g h t .

The s o l u t i o n was

p o u re d i n t o f r i l l g i r d l e s which had been c u t I n to t h e sa p wcod.
During November 1929 a stu d y was c o n d u c te d i n s o u th ­
e a s t e r n V i r g i n i a on a s ta n d o f tim b e r composed o f l o b l o l l y
p i n e and m ixed hardw oods.

One p h a s e o f t h i s s tu d y d e a l t

w ith a com parison o f m ethods o f removing u n d e s i r a b l e h a r d wcods and o f p r e v e n t i n g su b se q u e n t s p r o u t i n g .

Some t r e e s

w ere f e l l e d , some w ere g i r d l e d and r e c e i v e d no t r e a tm e n t ,
and o t h e r s were f r i l l e d and p o is o n e d w ith sodium a r s e n i t e .
One y e a r a f t e r t r e a t m e n t , 51 p e r c e n t o f t h e g i r d l e d t r e e s
had dead crowns and 85 p e r c e n t o f t h e f r i l l e d - t r e a t e d t r e e s
had dead crow ns.

I t was f u r t h e r r e p o r t e d t h a t 58 p e r c e n t o f

10
t h e f e l l e d hardwood stum ps had v ig o ro u s s p r o u t s , 55 p e r c e n t
o f t h e g i r d l e d t r e e s w ere s p r o u t i n g and o n ly 56 p e r c e n t o f
th e f r i l l e d - t r e a t e d t r e e s were s p r o u t i n g .

I t was a l s o no­

t i c e d t h a t t h e s p r o u t s o f t h e f r i l l e d - t r e a t e d t r e e s w ere
much s h o r t e r and l e s s v i g o r o u s th a n t h e s p r o u t s o f e i t h e r
t h e stumps o r t h e g i r d l e d t r e e s ( 4 5 ).
S to w a s se r ( 6 5 ) , w orking w ith p o ta s s iu m d ic h ro m a te and
o t h e r c h e m ic a ls i n 1930, r e p o r t e d t h a t when h o l e s w ere b o re d
i n t o t h e t r u n k s o f lom bardy p o p l a r t r e e s and c h e m ic a ls
p oured i n t o t h e h o l e s , o n ly t h e v e s s e l s d i r e c t l y above and
b elo w t h e h o l e s w ere a f f e c t e d .

H is c o n c lu s io n s were t h a t

t h i s method was n o t s a t i s f a c t o r y f o r k i l l i n g t h e t r e e s .
Cope and S p a e th made s i m i l a r o b s e r v a t i o n s In 1951 u s i n g
sodium a r s e n i t e to k i l l t h o r n - a p p l e ( 2 0 ) .

They made axe

c u t s aro u n d t h e stem s and l e f t a sp a c e betw een c u t s . They
found t h a t th e sodium a r s e n i t e d id n o t d i f f u s e l a t e r a l l y
more th a n o n e - h a l f In c h beyond t h e edges o f t h e c u t s .

They

t r e a t e d d u rin g t h e m onths o f F e b ru a ry , May, A ugust and No­
vember and r e p o r t e d t h e l a r g e s t p e r c e n t a g e o f k i l l i n g and ^
t h e l a r g e s t number o f s p r o u t s f o llo w e d th e May t r e a t m e n t s /
/

One p h a s e o f t h e i r e x p e rim e n ts compared t h e e f f e c t s o f p o i ­
so n in g u s i n g a f r i l l w ith t h e e f f e c t s p ro d u c ed by b o rin g
h o l e s t h r e e - q u a r t e r s o f an in c h i n d ia m e te r w ith an au g e r
b it.

They fo u n d t h e f r i l l and a u g e r - h o le m ethods to be

e q u a ll y e f f e c t i v e f o r s m a l l - s i z e d t r e e s , b u t r e p o r t e d t h a t
th e a u g e r - h o l e method d e c re a s e d i n e f f e c t i v e n e s s w ith l a r g e r

11
t r e e diam feters.

From t h e s e I n v e s t i g a t i o n s th e y d e v e lo p e d

t h e " C o rn e ll T ool" which h a s been u s e d e x t e n s i v e l y f o r t r e e
p o is o n in g .
P e a r s o n (54) r e p o r t e d on e x p e rim e n ts con ducted d u rin g
1954, 1955, and 1936 by t h e S o u th w e ste rn F o r e s t and Range
Experim ent S t a t i o n .

These i n v e s t i g a t i o n s were c a r r i e d o u t

to d e te rm in e i f t r e e p o i s o n in g c o u ld be u s e d a s a means o f
s ta n d improvement f o r p o n d e ro sa p i n e .

T re es p o is o n e d were

o v e r 6 i n c h e s i n d ia m e te r a t b r e a s t h e i g h t , and. t h e a u g e rh o l e m ethod o f p o i s o n i n g was employed, u s in g sodium a r s e n i t e .
On m ost t r e e s t h e h o l e s were r e f i l l e d a second tim e and a
k i l l o f a lm o st 100 p e r c e n t was o b t a i n e d .

H is c o n c lu s io n s

were t h a t u n d e s i r a b l e t r e e s p o is o n e d i n t h i s m anner r e l e a s e d
s e e d l i n g s and, by c a r r y i n g p a r t o f t h e snow l o a d on t h e i r
dead b ra n c h e s , gave them p r o t e c t i o n f o r a number o f y e a r s .
T here was a ls o s t r o n g e v id e n c e t h a t t r e e s k i l l e d by t h i s
m ethod d id n o t a t t r a c t t h e I p s b e e t l e which r e a d i l y i n f e s t s
u n t r e a t e d f e l l e d t r e e s I n t h e S o u th w e st.
F u r t h e r o b s e r v a t i o n s o f t h e same ex p e rim e n ts w ere pub­
l i s h e d i n 1939.

T h is p a p e r r e p o r t e d t h a t h o l e s b o re d more

o r l e s s p a r a l l e l to t h e c irc u m fe re n c e o f t h e t r e e p ro duced
q u i c k e r k i l l s th a n h o l e s b o re d s t r a i g h t i n t o t h e t r e e t o ­
wards t h e p i t h .

I t was a ls o s t a t e d t h a t h i g h e r s t r e n g t h so ­

l u t i o n s i n c r e a s e d t h e number o f t r e e s k i l l e d , o t h e r f a c t o r s
rem a in in g unchanged (44) .

12
Cook (18) d e s c r i b e d t h e r e s u l t s o f p o i s o n in g 13 d i f f e r ­
e n t s p e c i e s w ith sodium a r s e n i t e i n 1944.

He found g r e a t

d i v e r s i t y among t h e v a r i o u s s p e c i e s a s to r e s i s t a n c e to t h e
p o is o n and to t h e amount o f s p r o u t i n g a f t e r t r e a t i n g .

Com­

p l e t e k i l l i n g o f aspen clumps, o r i g i n a t i n g from r o o t s u c k e r s
o f an e x t e n s i v e sy stem , was found to he p r a c t i c a l l y impos­
sib le .

The ab o v e -g ro u n d p o r t i o n s w ere c o m p le te ly k i l l e d b u t

r o o t s u c k e r s came up i n abundance, o f t e n w i t h i n a few in c h e s
o f c o m p le te ly k i l l e d s te m s .

He co n clu d ed t h a t b e c a u se o f

t h e h a z a r d to man and b e a s t , and b e c a u se o f t h e v a r i a t i o n i n
e f f e c t i v e n e s s , sodium a r s e n i t e had o n ly l i m i t e d u s e f u l n e s s
i n f o r e s t and w i l d l i f e management.
Towards t h e end o f World War I I t r e e p o i s o n in g was g i v ­
en a f u r t h e r im p etu s w ith t h e a p p e a ra n c e o f new c h e m ic a ls ,
w hich were b e in g m a rk e te d a s s e l e c t i v e h e r b i c i d e s .

These

c h e m ic a ls w ere n o n - t o x i c to men and a n im a ls i n t h e q u a n t i ­
t i e s and c o n c e n t r a t i o n s u s e d ; e a r l y ex p e rim e n ts i n d i c a t e d
t h a t th e y m ig h t be v e r y e f f e c t i v e as t r e e - k i l l e r s .
One o f t h e s e c h e m ic a ls , ammonium s u lfa m a te ( t r a d e name
T^Ammate,,) , r e c e i v e d c o n s i d e r a b l e a t t e n t i o n ,
t h e s o u th .

e s p e c ia lly in

The u s e o f ,^Ammate,, was s t r o n g l y a d v o c ated by

Peevy in 1947 and 1949 f o r k i l l i n g u n d e s i r a b l e hardwoods i n
t h e so u th , e i t h e r by p l a c i n g t h e c r y s t a l s i n f r i l l s o r p o u r­
in g a w a te r s o l u t i o n i n them (55 and 5 6 ).
V a rio u s f o r m u l a t i o n s o f 2 ,4 - d i c h l o r o p h e n o x y a c e t i c a c id
(2,4-D) and 2 , 4 , 5 - t r i c h l o r o p h e n o x y a c e t i c a c id ( 2 ,4 ,5 - T ) ap-

15
p e a r e d on t h e m a rk e t a b o u t t h e same tim e a s "Animate."

These

c h e m ic a ls , e s p e c i a l l y t h e fo rm e r, became v e ry p o p u l a r a s
w e e d -k ille rs.

They w ere a ls o employed s u c c e s s f u l l y a s

b r u s h - k i l l e r s and some o f t h e e a r l i e s t a p p l i c a t i o n s f o r t h i s
p u rp o s e w ere f o r t h e c o n t r o l o f t r a n s m i s s i o n r i g h t s - o f - w a y
(61) .
I n 1950 t h e r e s u l t s o f e x t e n s i v e t e s t s w ith t h e s e two
c h e m ic a ls i n d i c a t e d t h a t 3 , 4 , 5-T was much m ore e f f e c t i v e
th a n 2,4-D a s a b r u s h - k i l l e r ( 2 ) .
The Dow Chemical Company r e p o r t e d i n 1950 t h a t a f t e r
f i v e y e a r s o f r e s e a r c h and f i e l d t e s t s , th e y found m o st
woody s p e c i e s c o u ld be k i l l e d w ith b a s a l b ark s p ra y s o f
2 ,4 -D and 2 , 4 , 5-T a p p l i e d d u rin g any season o f t h e y e a r .
Even many s p e c i e s w hich were r e s i s t a n t to f o l i a g e s p ra y s ap­
p e a re d to be s u s c e p t i b l e to b a s a l b ark s p ra y s ( 3 ) .
A com prehensive p a p e r by Chaiken (17) i n 1951 d e s c r i b e d
t h e r e s u l t s o b t a i n e d w ith many d i f f e r e n t c h e m ic a ls and d i f ­
f e r e n t t r e a t i n g m e th o d s.

He n o te d t h a t 2 , 4 , 5-T was much su­

p e r i o r to 2,4 -D i n k i l l i n g u n d e s i r a b l e hardwoods i n t h e
S o u th e a s t.

"Animate" a l s o proved to be v e r y p o t e n t b u t c o s t

two to t h r e e tim e s a s much as 2 , 4 , 5-T .

He a ls o n o te d t h a t

some t y p e s o f t r e a t m e n t w ere more e f f e c t i v e th a n o t h e r s when
a p p l i e d to t h e same s p e c i e s .

F o r example, sweetgum was

r e a d i l y k i l l e d by f o l i a g e s p ra y s o f 2 ,4 , 5-T b u t slo w to r e ­
spond to b a s a l s p r a y s .

Some o f t h e o ak s were e a s i l y k i l l e d

14
by b a s a l s p r a y s b u t sprouted, v i g o r o u s l y a f t e r f o l i a g e s p r a y ­
in g .

An em ulsion o f 2 , 4 , 5-T i n f r i l l s was fou nd t o be v e r y

slow i n k i l l i n g t r e e s b u t a ls o v e r y th o ro u g h .

No s p r o u t i n g

was d e t e c t e d on any t r e e t h a t h ad been p r o p e r l y t r e a t e d i n
t h i s manner w i t h a 2 ,4 , 5-T em u lsio n .

A b a s a l s p ra y o f

2 , 4 , 5-T i n o i l a l s o g ave good r e s u l t s b u t c o s t much more
th a n t h e f r i l l m ethod b e c a u se l a r g e r volumes and h i g h e r con­
c e n t r a t i o n s were n e e d e d .

I t a ls o a p p e a re d to be m ost e f f i ­

c a c io u s on t h i n - b a r k e d s p e c i e s .
I n 1953, Arend (6 ,7 ) r e p o r t e d on i n v e s t i g a t i o n s c a r r i e d
o u t i n M ich ig an w ith e s t e r s o f 2,4-D and 2 , 4 , 5-T.

He found

t h a t a 1 p e r c e n t , by w e ig h t, s o l u t i o n o f 2 , 4 , 5-T i n d i e s e l
o i l , a p p l i e d i n f r i l l s was v e ry e f f e c t i v e i n k i l l i n g scru b
o a k , aspen and r e d m ap le.
This same i n v e s t i g a t o r a ls o r e p o r t e d i n 1953 on t h e r e ­
s u l t s o f b a s a l s p r a y t r e a t m e n t s o f scru b asp e n w ith t h e same
two c h e m ic a ls ( 8 ) .

He o b se rv e d t h a t b a s a l sp ra y t r e a tm e n t s

w ere m ost e f f e c t i v e when a p p l i e d d u rin g t h e grow ing sea so n ,
from t h e tim e o f f u l l l e a f developm ent th ro u g h t h e end o f
Septem ber.

T re e s sp ra y e d d u rin g t h i s p e r i o d showed no s i g n s

o f s u c k e rin g when examined 3 y e a r s a f t e r t r e a t i n g .

T re es

t r e a t e d i n a s i m i l a r m anner b u t d u rin g th e dormant and e a r l y
growing s e a so n s s p r o u te d p r o l i f i c a l l y b e g in n in g w ith t h e
second y e a r a f t e r t r e a t i n g .

T re e s f r i l l e d and t r e a t e d w ith

w ith th e same s o l u t i o n s s p r o u te d t h e f i r s t y e a r a f t e r t r e a t ­

15
in g .

I t was a l s o o b s e rv e d t h a t s p r a y in g t h e t r e e tr u n k from

t h e ground to a p o i n t 4 f e e t above t h e ground was more e f ­
f e c t i v e th a n s p r a y i n g to a h e i g h t o f 2 f e e t above t h e ground,
even when t h e s t r e n g t h o f s o l u t i o n a p p l i e d to t h e 2 f o o t
sp ray was d o u b led .
I n 1953 Morrow (52) r e p o r t e d on i n v e s t i g a t i o n s cond uct­
ed n e a r I t h a c a , New Y ork.

Aspen was t r e a t e d by t h e b a s a l

sp ra y m ethod u s in g o i l s o l u t i o n s o f 2 ,4 -D and 2 , 4 , 5-T d u rin g
t h e grow ing and dorm ant s e a s o n s .

The r e s u l t s o f t h i s ex p e r­

im ent were n o t i n agreem ent w ith t h o s e r e p o r t e d by Arend (8 ).
Morrow found no a p p a r e n t d i f f e r e n c e s due to h e i g h t o f sp ra y
o r se a so n o f t r e a t i n g on su b se q u e n t s u c k e r in g .

No s p r o u t i n g

o f any k i n d was found on any o f h i s t e s t p l o t s .

H is e x p la ­

n a t i o n o f t h e d is a g re e m e n t i n r e s u l t s betw een h i s work and
t h a t o f Arend was t h e p o s s i b l e i n f l u e n c e o f t r e e v i g o r on
su b se q u e n t s u c k e r in g .

H is t r e e s w ere o f slow grow th, 60

y e a r s o l d , T/diereas Arend had condu cted h i s r e s e a r c h on v ig ­
o ro u s young a s p e n .

16
B. Development o f Chemical D ebarking i n Canada
The f i r s t e x p e rim e n ts w ith c h e m ic a ls to f a c i l i t a t e b a rk
rem oval w ere co n d u cted by A lex an d er R. W hite o f O n t a r io ,
Canada, i n Ju n e, 1941 (71) .

W hite based h i s i n v e s t i g a t i o n s

on t h e t h e o r y t h a t i f a " v e g e t a b le t o x i c a n t ” c o u ld be i n ­
j e c t e d i n t o t h e sap s tre a m o f a t r e e , d e a th m ig h t r e s u l t
q u i c k l y and p r e v e n t t h e t r e e from c o m p letin g n o rm a l, annual
gro w th.

He f u r t h e r re a s o n e d t h a t i f t h i s was ac co m p lish ed

and t h e t r e e d id n o t l o s e m o i s tu r e too r a p i d l y , t h e bark
m ig h t rem ain i n a p e e l a b le c o n d i t i o n f o r p e r h a p s 50 days b e ­
yond t h e norm al s a p - p e e l i n g se a so n .
At f i r s t h o l e s w ere b o re d i n t o t h e t r u n k s o f s p r u c e and
p o p l a r t r e e s a t ground l e v e l .

The p o is o n in g a g e n t was a

w a te r s o l u t i o n o f calciu m c h l o r i d e and sodium c h l o r a t e .

The

r e s u l t s o f t h e f i r s t a tt e m p t s w ere n e g a t i v e b e c a u s e i t was
im p o s s ib le to g e t enough s o l u t i o n in t o t h e h o l e s to k i l l t h e
tre e s.

I t was o b s e rv e d t h a t t h e r e was v e r y l i t t l e l a t e r a l

movement o f t h e s o l u t i o n from t h e h o l e s .
I n t h e l a t e summer o f 1941, t h e method o f a p p ly in g t h e
chem ical was changed and t h e t r e e s w ere g i r d l e d / //
/ A 5 per­
c e n t, by w e ig h t, w a te r s o l u t i o n o f calcium c h l o r i d e and so­
dium c h l o r a t e was a p p l i e d to t h e g i r d l e d a r e a and h e ld i n
c o n t a c t by means o f a w a t e r - t i g h t dam a t th e b a se o f t h e
g i r d l e ; d e t a i l s o f t h i s dam w ere l a c k i n g i n t h e l i t e r a t u r e .
The c h e m ic a ls w ere u s e d i n a r a t i o o f 3 p a r t s calcium c h lo -

17
r i d e to 1 p a r t sodium c h l o r a te *

T h is m ethod a p p e a re d to be

p a r t i a l l y s u c c e s s f u l on b o th s p ru c e and a s p e n .

The crowns

o f t h e t r e e s w ere k i l l e d by t h e c h e m ic a ls b u t t h e expen se o f
t h e method and t h e d i f f i c u l t i e s e n c o u n te re d i n f a s h i o n i n g a
w a t e r - t i g h t dam aroun d t h e g i r d l e l e d to t h e u s e o f a t h i c k
p a s t e to w ard s t h e end o f A ug ust.

The p a s t e c o n ta in e d t h e

same ch e m ica ls and was sm eared on t h e g i r d l e d a r e a .
t i r e g i r d l e was w rapped w ith c h e e s e c l o t h .

The en­

B e fo re a p p ly in g

t h e c h e m ica l, t h e g i r d l e was sc o re d to a d epth o f ab o u t o n eq u a r t e r o f an i n c h .

P o p l a r was u sed w ith t h i s method and

a l l t r e e s were k i l l e d w i t h i n 7 days a f t e r t r e a t i n g .

I t was,

how ever, too l a t e i n t h e se a so n to i n f l u e n c e t h e p e e i a b i l i t y
o f t h e t r e e s d u rin g t h e c u r r e n t gro\ving se a so n , b u t t h e
t r e e s p e e le d f a i r l y w e ll t h e f o llo w in g s p r in g (71) .
I n 1942 t h e p r o c e s s o f a p p ly in g c h e m ic a ls to t r e e s f o r
t h e p u rp o se o f d e b a rk in g was p a t e n t e d by White ( 5 3 ) .

During

t h e same y e a r many p u lp and lum ber companies co n d u cted t e s t s
to d e te rm in e t h e e f f e c t i v e n e s s o f t h e c h e m ic a l.

Burk (15)

r e p o r t e d t h e e x p e rim e n ts c a r r i e d o u t on sp ru c e w hich had been
t r e a t e d w ith Cambicide A ( t h i s was a commercial p ro d u c t
■which c o n s i s t e d o f p r e p a r e d r o l l s o f p a p e r bandage, c o a te d
w ith a m ix tu r e o f sodium c h l o r a t e and calcium c h l o r i d e ) .

It

was n o te d t h a t some s p ru c e t r e e s t r e a t e d d u rin g t h e s a p p e e l i n g se a so n d id n o t p e e l e f f e c t i v e l y a f t e r t h e s a p - p e e l i n g
sea so n was o v e r . I Some s t i c k s p e e l e d r e a d i l y b u t some d id

18
not peel at a l l .

I t was con clud ed t h a t t h e ch em ical d id n o t

g iv e s a t i s f a c t o r y r e s u l t s o v e r t h e e n t i r e l e n g t h o f t h e
t r e e , t h e s t i c k s from t h e u p p e r p o r t i o n s o f t h e t r u n k b ein g
much more d i f f i c u l t to p e e l t h a n t h o s e from t h e lo w e r r e ­
g io n s.

S i m i l a r c o n c lu s i o n s w ere drawn a f t e r o b s e r v in g m a te ­

r i a l which h ad b een ru n th ro u g h a drum b a r k e r .
I n 1945 t e s t s w ere u n d e r ta k e n by t h e F o r e s t P r o d u c t s
L a b o r a t o r i e s o f Canada a t t h e Dominion F o r e s t E xperim ent
S t a t i o n a t Petawawa.

A v a r i e t y o f c h e m ic a ls and t r e e s p e ­

c i e s were employed in t h e s e e x p e rim e n ts and t r e a tm e n t s w ere
made d u rin g Ju n e , J u l y and August.
I t was o b se rv e d t h a t t h e v a r i o u s c h e m ic a ls r e a c t e d i n
two d i s t i n c t ways.

Some o f them r e a c t e d i n a v e r y r a p i d

m anner, c a u s in g d e f o l i a t i o n and d e a th w i t h i n a week.

The

a c t i o n o f o t h e r s was much slo w e r, t h e t r e e s r e t a i n i n g t h e i r
l e a v e s f o r w eeks, and i n some c a s e s up u n t i l t h e tim e o f
norm al l e a f f a l l .

I t was d e te rm in e d t h a t t h e f a s t - a c t i n g

ch e m ica ls w ere t h e m ost e f f e c t i v e i n f a c i l i t a t i n g b a rk r e ­
m oval.

One o f t h e b e s t c h e m ic a ls o b se rv e d was a com b ination

o f a r s e n i c t r i o x i d e and c a u s t i c soda i n a p a s t e form.
T re atm en ts a p p l i e d d u rin g t h e e a r l y p a r t o f t h e norm al sa p p e e l i n g sea so n gave b e t t e r r e s u l t s th a n t h o s e made to w ard s
t h e end o f summer (52) ,
By 1946 i t had d e f i n i t e l y been e s t a b l i s h e d t h a t s o lu ­
t i o n s and p a s t e s c o n t a i n i n g e i t h e r sodium a r s e n i t e o r a r ­

19
s e n i c t r i o x i d e , when a p p l i e d to g i r d l e s , w ere t h e m o st e f ­
f e c t i v e c h e m ic a ls f o r l o o s e n i n g b a r k .

However, b e c a u s e o f

t h e h a z a rd s i n v o lv e d i n u s i n g a r s e n i c compounds, t h e s e a r c h
f o r a " p e r f e c t ” chem ical c o n tin u e d .

T h e r e f o r e , i t was p r p -

posed to t e s t t h e recently* developed w e e k - k i l l e r s (1)/.
I n 1947 H a le (53) summarized t h e work o f t h e F o r e s t
P r o d u c t s L a b o r a t o r i e s i n c o n n e c tio n w ith t h e ch em ical t r e a t ­
ment o f t r e e s to f a c i l i t a t e b ark re m o v a l.

New c h e m ic a ls had

been t e s t e d b u t a r s e n i c p a s t e m i x tu r e s s t i l l a p p e a re d to be
th e b e s t.

I t was o b s e rv e d , how ever, t h a t w h ile a r s e n i c ap­

p a r e n t l y had some t o x i c e f f e c t s to w ards i n s e c t s ,

"Ammate"

had none, w ith t h e r e s u l t t h a t t r e e s t r e a t e d w ith t h i s chami c a l were s u b j e c t to s e r i o u s b a rk i n s e c t a t t a c k .

T his

caused th e b a rk to b re a k up i n t o sm all p i e c e s alo n g t h e n u ­
merous g a l l e r i e s making hand p e e l i n g v e r y d i f f i c u l t .

Coni­

f e r s p e e le d r e a d i l y i n th e drum b a r k e r , b u t i t was found
t h a t th e s t i c k s from t h e u p p e r p a r t s o f aspen t r e e s d id n o t
p e e l c l e a n l y , n e c e s s i t a t i n g a second t r i p th ro u g h .
The sodium s a l t o f 2 ,4 -D a p p l i e d as a w a te r p a s t e
showed p ro m ise o f b e in g an e f f e c t i v e chem ical f o r d e b a rk in g
when u se d d u rin g J u n e .
g iv e f a v o r a b l e r e s u l t s .

T re es t r e a t e d a f t e r lu n e d id n o t
No ev id e n c e o f s t a i n o r b a rk i n ­

s e c t s was found on 2,4 -D t r e a t e d t r e e s .
E x p erim en ts co n d u cted a t S te v e n s , O n ta rio d u rin g 1947
and 1948 were r e p o r t e d by M cIntosh ( 4 6 ,4 7 ) .

Among o t h e r

20
t h i n g s , w e ig h t r e d u c t i o n o f t r e a t e d t r e e s ;was s t u d i e d and
com p ariso ns w ere made betw een t r e a t e d and u n t r e a t e d t r e e s ,
a s w e ll a s betw een d i f f e r e n t chem icals*

W eight r e d u c t i o n

was d eterm in ed by means o f t e s t s e c t i o n s c u t from s t a n d i n g ,
t r e a t e d t r e e s and compared w ith s i m i l a r s e c t i o n s ta k e n from
u n tre a te d tr e e s .

I t was found t h a t w h ile w e ig h t r e d u c t i o n s

o f up to 10 pounds p e r cu b ic f o o t were o b t a i n e d w ith some
c o n i f e r s , hardwoods i n g e n e r a l showed l i t t l e o r no w e ig h t
re d u c tio n *

There was no s i g n i f i c a n t d i f f e r e n c e o f o n e chen-

i c a l o v e r a n o th e r i n re d u c in g w e ig h t.
A s u b se q u e n t r e p o r t c o n c e rn in g w e ig h t r e d u c t i o n was
p u b l i s h e d i n 1949 (4 8 )•

T h is r e p o r t co v ered e x p e rim e n ts i n

which some t r e e s w ere g i r d l e d and t r e a t e d , some were g i r d l e d
o n ly , and o t h e r s were u se d u n t r e a t e d a s c o n t r o l s .
o d s were u se d to check w eig h t re d u c tio n *

Two m eth­

One m ethod was to

f e l l t r e e s a b o u t f o u r m onths a f t e r th e y had been g i r d l e d and
tre a te d .

S e c t i o n s w ere t a k e n from a l l p o r t i o n s o f t h e

t r u n k s and compared w ith s i m i l a r s e c t i o n s ta k e n from t h e
norm al t r e e s f e l l e d a t t h e same tim e .

The second method em­

p lo y e d t h e same te c h n iq u e b u t was n o t co n d u cted u n t i l a y e a r
a f t e r t r e a t i n g and i n c lu d e d th e t r e e s which h ad been g i r d l e d
but not tr e a te d .

I t was found t h a t ja c k p in e and balsam f i r

t r e e s were n o t much l i g h t e r i n w e ig h t th a n t r e e s which had
been g i r d l e d w ith o u t a chem ical tre a tm e n t*

Aspen and balsam

p o p l a r showed no s i g n i f i c a n t r e d u c t io n i n w e ig h t when com-

21
p a r e d to u n t r e a t e d t r e e s f o u r m onths a f t e r t r e a t i n g .

T re a t­

ed and g i r d l e d w h i t e b i r c h a c t u a l l y were h e a v i e r th a n un­
t r e a t e d t r e e s when compared f o u r months a f t e r t r e a t i n g .

The

wood o f hairdwood t r e e s w hich had been g i r d l e d and t r e a t e d
was i n some i n s t a n c e s h e a v i e r th a n t h a t o f hardw oods which
had been g i r d l e d o n l y , when checked one y e a r a f t e r t r e a t i n g .
M cIntosh and H a le (50) p r e s e n t e d a d d i t i o n a l in f o r m a t i o n
p e r t a i n i n g to t h e e f f e c t s o f d i f f e r e n t c h e m ic a ls and tim e o f
tr e a tm e n t on t h e d e b a rk in g o f numerous hardwood and softwood
s p e c ie s .

They co n clu d ed t h a t a p a s t e o f one p a r t a r s e n i c

t r i o x i d e and one p a r t c a u s t i c soda was t h e b e s t f o r d eb a rk ­
in g b o th c o n i f e r s and hardw oods.

A co m b in atio n o f a r s e n i c

and ammonium s u lf a m a te was n e x t b e s t .

Ammonium s u lfa m a te

a lo n e was e f f e c t i v e i n l o o s e n in g t h e bark o f some s p e c i e s
but not a l l .

The sodium s a l t o f 2,4-D was e r r a t i c i n p e r ­

form ance and was n o t recommended a s a b a r k - p e e l i n g c h o n ic a l.
I t a p p e ared to be p a r t i a l l y s u c c e s s f u l on t h e lo w e r p o r t i o n s
o f t h e tr u n k , b u t s t i c k s from t h e u p p er p o r t i o n p e e le d w ith
d iffic u lty .

A ll c h e m ic a ls w ere a p p l i e d a s p a s t e s , which

w ere s p re a d on a band o f c r i n k l e d p a p e r .

The t r e a t e d p a p e r

was p u l l e d t i g h t l y around t h e g i r d l e d p o r t i o n o f t h e t r e e
t r u n k and h e ld f a s t w ith an u p h o l s t e r y t a c k .
s e rv e d

I t was ob­

t h a t i n m ost i n s t a n c e s c o n i f e r s p e e le d b e t t e r th a n

hardwoods r e g a r d l e s s o f t h e chem ical u s e d .

28
T rees t r e a t e d d u rin g Ju n e and J u l y , w ith t h e more e f ­
f e c t i v e c h e m ic a ls , p e e le d e a s i l y when th e y were f e l l e d t h e
fo llo w in g O c to b e r.

They were a ls o e a s i l y p e e le d when t e s t e d

t h e fo llo w in g y e a r .
The e f f e c t i v e n e s s o f August t r e a t m e n t s seemed to de­
pend, to a l a r g e e x t e n t , on t h e s p e c i e s t r e a t e d .

Balsam f i r

was r e a d i l y p e e l e d when f e l l e d t h e fo llo w in g O c to b e r b u t a s ­
p en , balsam p o p l a r , ja c k p i n e , and s p ru c e p e e le d o n ly
s l i g h t l y b e t t e r th a n n o rm a l, u n t r e a t e d t r e e s f e l l e d a t th e
sam e.tim e.

T re a te d w h ite b i r c h was j u s t a s d i f f i c u l t to

p e e l a s u n t r e a t e d t r e e s f e l l e d a t t h e same tim e .

Most t r e e s

t r e a t e d i n A ugust and t e s t e d t h e fo llo w in g Ju ne p e e le d a s
e a s i l y o r more e a s i l y th a n u n t r e a t e d c o n t r o l t r e e s .
With t h e e x c e p tio n o f balsam f i r , a l l s p e c ie s which had
been t r e a t e d i n Septem ber and f e l l e d i n O c to b e r w ere as d i f ­
f i c u l t to p e e l a s u n t r e a t e d t r e e s f e l l e d a t t h e same tim e .
T re e s t r e a t e d i n Septem ber and t e s t e d t h e f o llo w in g y e a r
w ere o b serv e d to p e e l more e a s i l y as t h e summer p r o g r e s s e d .
Jack p in e and b la c k s p ru c e gave t h e p o o r e s t r e s u l t s when
t e s t e d th e f o llo w in g y e a r .
The same two i n v e s t i g a t o r s (34) r e p o r t e d i n December,
1949, th e developm ent o f a g a s o lin e -p o w e re d g i r d l i n g t o o l
which was r e p o r t e d to sp eed up g r e a t l y t h e t r e a t i n g p r o c e s s .
They a l s o n o te d t h a t r e c e n t t e s t s had i n d i c a t e d t h e u s e o f
p a s t e s w ith o u t t h e p r o t e c t i v e p a p e r band a p p e a re d to be as

25
s u c c e s s f u l In l o o s e n i n g b a rk a s t h e commonly a c c e p te d method
o f u s i n g a band w ith t h e p a s t e .
By 1951 i t had d e f i n i t e l y been e s t a b l i s h e d t h a t a p p ly ­
in g a t h i n w a te r p a s t e o f a r s e n i c to t h e g i r d l e d a r e a o f a
t r e e w ith a p a i n t b ru sh and n o t w rapping i t was t h e m o st
econom ical method y e t t r i e d .
a s any o t h e r m ethod t r i e d .

I t was a l s o j u s t as e f f e c t i v e
A r e p o r t sum m arizing t h e r e s u l t s

o f t e s t s u s i n g 25 d i f f e r e n t ch e m icals showed t h a t v a r i o u s
forms o f a r s e n i c were s t i l l t h e m ost e f f e c t i v e i n l o o s e n i n g
t h e b a rk o f t r e e s and c o n t r o l l i n g b ark i n s e c t s .

I t was a l s o

p o i n t e d o u t t h a t when c h e m ic a ls w ere n o t a p p l i e d ev e n ly
around t h e g i r d l e , t h e e a s e o f p e e l i n g was n o t u n ifo rm .

She

chem ical ap p eared to a f f e c t o n ly t h e b ark d i r e c t l y above t h e
p o in t o f a p p lic a tio n .

The bark rem ained g re e n above a r e a s

o f th e g i r d l e which had n o t re c e iv e d s u f f i c i e n t c h e m ic a l.
I t was a ls o o b se rv e d t h a t w ith t r e e s which c o n ta in e d normal
r e s i n c a n a l s , i t was n e c e s s a r y to a p p ly t h e chem ical Immedi­
a t e l y a f t e r g i r d l i n g , o t h e r w is e a f i l m o f r e s i n c o a te d t h e s u r­
f a c e o f th e g i r d l e d a r e a and impeded a b s o r p t i o n o f t h e chomi c a l i n t o t h e sapwood (49) .

C* Chemical D ebarking i n t h e U n ite d S t a t e s
Experim ents w i t h c h e m ic a ls , f o r th e p u rp o s e o f d eb ark­
in g t r e e s , were s t a r t e d i n t h e U n ite d S t a t e s s h o r t l y a f t e r

24
A. R. W hite announced h i s p r o c e s s i n Canada.

However, i t

was n o t u n t i l 1948 t h a t l a r g e s c a l e t e s t s w ere u n d e r ta k e n .
The Arm strong F o r e s t Company o f lo h n so n b u rg , P e n n s y l­
v a n i a , was t h e p i o n e e r t e s t i n g agency i n t h i s c o u n try .

On

t h e b a s i s o f t h e i r e x t e n s i v e t e s t s , th e y p u b l i s h e d a r e p o r t
c o n ta in in g recommended m ethods o f t r e a t i n g t r e e s , o r g a n i z i n g
t r e a t i n g crews and p la n n in g l a r g e s c a l e o p e r a t i o n s ( 1 0 ) .
They ad v o c ated t h e u s e o f a w a te r s o l u t i o n o f sodium a r s e n ­
i t e a p p l i e d to g i r d l e d t r e e s by means o f a p a i n t b r u s h and
bucket o r a ta n k -fe d o u t f i t .

I t was r e p o r t e d t h a t a f i v e -

man crew, c o n s i s t i n g o f a forem an, t h r e e g i r d l e r s , and one
p a i n t e r co u ld t r e a t enough tim b e r to p ro d u c e ab o u t 100 c o rd s
p e r 8 -h o u r day.

A s e a s o n in g p e r io d o f 8 to 14 m onths was

su g g e ste d to a i d i n t h e c o m p letio n o f b a rk s e p a r a t i o n .

T his

p e r io d was s a i d to be s u f f i c i e n t to e l i m i n a t e a lm o st a l l
hand p e e l i n g ; m ost o f t h e bark s lo u g h in g o f f e i t h e r on t h e
s ta n d in g t r e e o r th ro u g h su b se q u e n t h a n d lin g .
I n 1952 t h e A rm strong F o r e s t Company p u rc h a s e d U. S.
P a t e n t Ho. 2 ,3 2 4 ,9 6 8 o r i g i n a l l y g r a n te d to A. R. White, cov­
e r in g t h e u s e o f c h e m ic a ls f o r d e b a r k i n g t r e e s , and made i t
a v a i l a b l e f o r p u b l i c u s e I n t h i s c o u n try ( 4 ) .
B e n n e tt (11) d e s c r i b e d o t h e r work u n d e r ta k e n by t h e
Armstrong F o r e s t Company and r e p o r t e d some i n t e r e s t i n g ob­
se rv a tio n s .

I t was n o t e d t h a t a c le a n g i r d l e w ith a b s o l u t e ­

l y no c u t s made i n t o t h e sapwood was t h e b e s t m ethod o f p r e ­

25
p a rin g th e t r e e s f o r tre a tm e n t.

S c o rin g o r c u t t i n g i n t o t h e

sapwood was re g a rd e d a s p r e v e n t in g t h e upward t r a n s l o c a t i o n
o f th e p o is o n and c a u s in g g re en s t r e a k s i n t h e h a rk above
such i n c i s i o n s .

I t was a l s o fo und t h a t alm o st a l l hardwoods

s p r o u te d a f t e r t r e a t i n g w ith sodium a r s e n i t e , t h u s i n s u r i n g
r e g e n e r a t i o n o f th e s t a n d .

T e s ts made w ith t h e b a rk o f a r -

* s e n i t e - t r e a t e d t r e e s i n d i c a t e d t h a t t h e p o is o n d i d n o t-.E f­
f e c t t h e u s e o f t h e b a rk f o r t a n n i n e x t r a c t i o n .
Among o t h e r c h e m ic a ls t e s t e d a s s u b s t i t u t e s f o r a r s e n i c ,
Dow D e f o l ia n t (Sodium m o n o c h lo ro a c e ta te ) and v a r io u s form u­
l a t i o n s o f 2,4-D and 2 , 4 , 5-T were t r i e d by many i n v e s t i g a ­
to rs .

Cook and H a m ilto n (19) and W ilcox (73) r e p o r t e d t h a t

t h e s e c h o n ic a ls w ere n o t as e f f e c t i v e as sodium a r s e n i t e i n
f a c i l i t a t i n g bark re m o v a l.

Wilcox r e p o r t e d t h a t Dow D e f o li­

a n t a p p l i e d to g i r d l e d t r e e s i n r u b b e r r e s e r v o i r s produced
p e e l i n g com parable to a r s e n i c b u t when a p p l i e d by t h e con­
v e n t i o n a l b ru s h method gave v e ry p o o r r e s u l t s .

He a l s o ob­

s e rv e d t h a t 2 ,4 -D and 2 , 4 , 5-T a p p l i e d to g i r d l e s i n r u b b e r
r e s e r v o i r s w ere l e s s e f f e c t i v e th a n Dow D e f o l i a n t .
Cook and H a m ilto n (19) a g re e d w ith B e n n e tt t h a t s c o r in g
o f t h e sapwood r e t a r d e d t h e upward flo w o f t h e c h e m ic a ls .
W ilcox (7 3 ), how ever, fo und no d i f f e r e n c e e x i s t e d betw een
s c o re d and u n s c o re d t r e e s as to p e e l a b i l i t y . ,
/

Arend (5) worked w ith 2,4-D , 2 , 4 , 5-T and "Animate" i n
M ich ig an .

He t e s t e d t h e t h r e e c h e m ic a ls on asp en , r e d

26
m ap le, w h ite o ak , and n o r t h e r n p i n o ak .

H is r e s u l t s showed

t h a t none Gf t h e c h e m ic a ls was e f f e c t i v e on any o f t h e s p e c i e s
ex c ep t r e d m a p le .

The h a r k o f r e d m aple c o u ld he s t r i p p e d

o f f a t th e end o f t h e secon d growing s e a so n h u t t h e h a rk o f
a l l t h e o t h e r s rem ain ed t i g h t .

The "Animate” c r y s t a l s were

a p p l i e d i n n o tc h e s sp a c e d every 4 to 6 in c h e s aro u n d t h e
hase o f th e t r e e .

E s t e r s o f 2,4-D and 2 , 4 , 5-T w ere a p p l i e d

as b a s a l s p ra y s i n a c o n c e n t r a t i o n o f 8 pounds a . h . g .
d ie se l o i l .

in

T re e s w ere s p ra y e d from t h e ground to h e i g h t s

o f 2 o r 4 f e e t above g ro u n d .

T re atm e n ts were a p p l i e d d u rin g

t h e dormant se a so n , s p r i n g , s a p - p e e l i n g s e a so n ( a f t e r f u l l
l e a f developm ent) , and i n t h e f a l l .
Day e t a l .

(23) a ls o i n v e s t i g a t e d t h e u s e o f 2 ,4 -D and

2 , 4 , 5-T i n M ic h ig a n .

T re a tm e n ts w ere made on t r e m b lin g a s ­

pen and l a r g e t o o t h a sp e n .

Water and d i e s e l o i l w ere u s e d

as c a r r i e r s and t r e a tm e n t s in c lu d e d b a s a l s p r a y in g , f r i l l
g i r d l e p lu s c h e m ic a l, and p e e le d g i r d l e p l u s c h e m ic a l.

A ll

t e s t s u s in g w a te r s o lu tio n s ^ p r o d u e e d n e g a t i v e r e s u l t s .

It

was concluded t h a t t h e waxy b a rk o f aspen allo w ed o n ly a
(iu all amount o f s o l u t i o n to he ab sorbed, o r t h a t t h e s o l u ­
t i o n was washed o f f b e f o r e t h e chem ical c o u ld be ta k e n in t o
t h e sap stre a m .
D ie s e l o i l u se d a lo n e p roduced n e g a t i v e r e s u l t s .

The

amine s a l t s and an e s t e r o f 2,4 -D , a s w e ll a s an e s t e r o f
*A cid e q u i v a l e n t p e r 100 g a l l o n s o f s o l u t i o n .

27
2 , 4 , 5-T, i n d i e s e l o i l (8 pounds a . h . g . ) p ro d u ced v a r i a b l e
re su lts.

The e s t e r o f 2 , 4 , 5-T was o b s e rv e d t o be t h e b e s t ,

fo llo w e d by an e s t e r o f 2 ,4 -D w h ile t h e amine s a l t o f 2 ,4 -D
produced i n c o n s i s t e n t r e s u l t s .

Stem s p r a y i n g was r e p o r t e d

to be more e f f e c t i v e th a n g i r d l i n g f o llo w e d by s p r a y i n g .

No

b a rk lo o s e n in g was o b s e rv e d i n t r e e s t h a t d ie d d u rin g t h e
f i r s t grow ing se a so n , b u t pulpwood s t i c k s c u t from t h e s e
t r e e s t h e f o llo w in g November ap p e a re d to p e e l more e a s i l y
th a n u n t r e a t e d t r e e s c u t a t t h e same tim e .
I n v e s t i g a t i o n s co n d u cted by t h e S t a t e U n i v e r s i t y o f New
York, C o lle g e o f F o r e s t r y , were d e s c r ib e d by Jahn (4 1 ).
These e x p e rim e n ts w ere p erfo rm ed on hardwoods and so ftw oods
u s i n g sodium a r s e n i t e a p p l i e d to a p e e le d g i r d l e .

I t was

o b se rv e d t h a t t h e b e s t r e s u l t s were o b t a in e d when t h e t r e e s
were t r e a t e d i n Ju n e, a lth o u g h t h e t r e a t m e n t a p p e a re d t o be
e f f e c t i v e a t any tim e d u rin g t h e s a p - p e e l i n g s e a so n .

T re at­

m ents a p p lie d b e f o r e and a f t e r t h e s a p - p e e l i n g se a so n gave
poor r e s u lts .

Dominant and co-dom inant t r e e s o f good v i g o r

respond ed somewhat b e t t e r th a n t r e e s o f o t h e r c l a s s e s and o f
poor v ig o r.

T re es betw een 8 and 17 in c h e s d ia m e te r a t b r e a s t

h e i g h t a l l gave good r e s u l t s , w h i l e th o s e above and below
t h a t l i m i t som etimes gave p o o r e r r e s u l t s .
By means o f r a d i o - a c t i v e a r s e n i c , i t was d e te rm in e d
t h a t t h e chem ical l e f t t h e u n s c o re d , g i r d l e d a r e a s v e r y r a p ­
id ly .

A pprox im ately 95 p e r c e n t o f t h e a r s e n i c was gone a t

28
t h e end o f 48 h o u rs when a p p l i e d to spruce*

The movement

away from t h e g i r d l e was slo w e r and more g r a d u a l when t h e
g i r d l e had been s c o r e d .

However, i t was o b s e rv e d t h a t s c o r ­

in g had no e f f e c t on t h e p e e l i n g c h a r a c t e r i s t i c s o f t h e
b a rk ; t r e a t e d t r e e s w i t h s c o re d g i r d l e s p e e le d j u s t a s e a s i ­
l y a s t h o s e which w ere u n s c o re d .
I t was concluded t h a t b ecau se t h e c h a n ic a l do es l e a v e
th e g i r d l e d f a c e so r a p i d l y , t h e damage to w i l d l i f e sh o u ld
be a t a minimum.
I t was recommended t h a t c o n i f e r s be a llo w e d to s t a n d
f o r t h r e e months a f t e r t r e a tm e n t and (hardwoods n o t be f e l l e d
u n t i l a f t e r f r e e z i n g and th aw ing had ta k e n p l a c e .

These pe­

r i o d s were d e te rm in e d to be s u f f i c i e n t to g iv e good b a rk
p e e lin g .
S a r l e s (60) r e p o r t e d t h a t sodium a r s e n i t e a p p l i e d to
g i r d l e d w h ite p in e a s l a t e as Septem ber 24 gave e x c e l l e n t
r e s u l t s i n lo o s e n i n g t h e b a r k .

O n e -h a lf g a l l o n o f th e chem­

i c a l was a p p l i e d to 58 g i r d l e d t r e e s by means o f a p a i n t
b ru sh .

T w e n ty -th re e o f t h e t r e e s were f e l l e d th e f i r s t week

o f November and a l l

p e e le d s a t i s f a c t o r i l y .

were c u t by th e end

o f t h e f o llo w in g Jan u a ry and t h e y too

p e e le d v e ry w e ll; t h e b ark was r e p o r t e d to
lo n g , l a r g e p i e c e s .

The o t h e r 35

h av e come o f f i n

29
E* The P e r i o d i c l t y o f Secondary Growth and t h e R e l a t e d
Changes 0 c c u r r i n g i n t h e Cambium and A d ja c e n t T i s s u e s
o f Woody P l a n t s
The e x a c t m anner i n w hich c h e m ic a ls f a c i l i t a t e b a rk
l o o s e n i n g h a s n o t been i n v e s t i g a t e d to any g r e a t e x t e n t .
Numerous t h e o r i e s on t h e m e c h a n ic s o f c h e m ic a l b a rk l o o s e n ­
in g have been p r e s e n t e d , b a s e d on t h e c o n d i t i o n o f t h e camb i a l r e g io n d u rin g t h e norm al s a p - p e e l i n g se a so n .

T here­

f o r e , i t was th o u g h t t h a t a b r i e f summary o f t h e s e t h e o r i e s ,
and a r e v ie w o f some o f t h e more p e r t i n e n t s t u d i e s condu cted
on t h e cambium and a d j a c e n t t i s s u e s d u rin g d i f f e r e n t se a so n s
o f t h e y e a r , would be a p p r o p r i a t e b e f o r e d e s c r i b i n g t h e e f ­
f e c t s o f c h e m ic a ls on p l a n t t i s s u e s .
A lthough t h e t h e o r i e s advanced by v a r i o u s i n v e s t i g a t o r s
c o n c e rn in g ch em ical d e b a rk in g o f t r e e s v a r y a s to d e t a i l ,
m ost a g r e e on c e r t a i n fu n d a m e n ta ls .

They s t a t e t h a t d u rin g

t h e s a p - p e e l i n g s e a s o n , t h e cam bial r e g io n p o s s e s s e s ex­
t r e m e ly t h i n w a l l s which r e p r e s e n t a p la n e o f w eakness, a l ­
lo w in g t h e b a rk to be p e e le d r e a d i l y .

At t h e c l o s e o f t h e

s a p - p e e l i n g s e a so n , t h e w a l l s become r e l a t i v e l y t h i c k and
th e re g io n o f c l e a v a b i l i t y d isa p p e a rs.

They f u r t h e r re a so n

t h a t i f a t r e e can be k i l l e d q u i c k ly d u rin g t h e s a p - p e e l i n g
s e a s o n , so t h a t t h e cam bial r e g io n i s f i x e d i n a t h i n - w a l l e d
c o n d i t i o n , i t s h o u ld be p o s s i b l e to p e e l o f f t h e b ark lo n g
a f t e r t h e norm al s a p - p e e l i n g season h a s te r m i n a t e d (27,33,4-1,
4 9 ,7 1 ) .

/

30
The i n i t i a t i o n o f c a m b ial a c t i v i t y i n t h e s p r in g h a s
b een s t u d i e d by many i n v e s t i g a t o r s , who h av e o b s e rv e d t h a t
i t s t a r t s i n t h e a p i c a l p o r t i o n s o f t h e tw ig s and s p r e a d s
b a s i p e t a l l y th ro u g h t h e t r u n k to t h e r o o t s .

I t h a s been

a g re e d by many o b s e r v e r s t h a t t h e s t i m u l u s f o r t h i s i n i t i a ­
t i o n i s p ro b a b ly a grow th hormone ‘w hich o r i g i n a t e s i n t h e
t e r m i n a l p o r t i o n s o f t h e b r a n c h e s when t h e buds s t a r t to
s w e ll i n t h e s p r i n g .
Brown (14) n o t e d t h a t c e l l d i v i s i o n began, in t h e u p p e r
p o r t i o n s o f t h e t r u n k s o f w h ite p in e b e f o r e i t began i n th e
lo w e r p o r t i o n s .

S w a rb ric k (66) o b s e rv e d a s w e llin g o f th e

c a m b ia l re g io n a t t h e same tim e t h a t th e buds were b e g in n in g
to i n c r e a s e i n s i z e .

L ik e w is e , h e found t h a t xylern d i f f e r ­

e n t i a t i o n began i n t h e t e r m i n a l r e g io n s o f a l l sh o o ts and
s p re a d downwards to w ard s t h e r o o t s .

P r i e s t l e y (58) r e p o r t e d

cam bial a c t i v i t y a s b e in g i n i t i a t e d i n t h e d e v e lo p in g buds;
Brown (13) and Esau (50) o b s e rv e d i t s t a r t i n g j u s t below t h e
f o l i a r b uds.
ity .

They a l l r e p o r t e d a b a s i p e t a l s p r e a d o f a c t i v ­

Most o f t h e s e i n v e s t i g a t o r s a ls o n o t i c e d t h a t c e s s a ­

t i o n o f a c t i v i t y i n t h e f a l l was i n e x a c t ly t h e same o r d e r
as i n i t i a t i o n i n t h e s p r i n g .

A c t i v i t y t e r m i n a te d f i r s t i n

t h e tw ig s and s p r e a d downward th ro u g h t h e t r u n k w ith t h e
r o o t s b e in g t h e l a s t p a r t o f t h e p l a n t to go i n t o a dormant
c o n d itio n (1 3 ,1 4 ,5 8 ,6 6 ).

A ccording to Esau (30) t h e xylem

c e l l s o b se rv e d i n V i t i s had t h i c k , l i g n i f i e d w a l l s , w h ile

31
t h e cambium and a d j a c e n t phloem c o u ld n o t be d i s t i n g u i s h e d
on t h e b a s i s o f w a l l t h i c k n e s s .

She r e p o r t e d b o th cambium

and phloem m o th e r c e l l s a s h a v in g t h i c k , u h l i g n i f i e d w a l l s .
Brown (14) o b s e rv e d t h a t an i n i t i a t i n g l a y e r c o u ld n o t be
i d e n t i f i e d i n w h it e p i n e b e c a u s e t h e m e r i s t e m a t i c c e l l s on
b o th s i d e s h ad t h e same s i z e , form , and p r o to p la s m ic con­
t e n t s a s t h e t r u e cambium.

The cam bial r e g io n h a s -b e e n ob­

s e r v e d t o be 7 to 10 c e l l s w ide i n t h e stem o f w h ite p in e
(14) and 4 to 6 c e l l s w ide i n t h e b ra n c h e s o f a p p le t r e e s
(6 6 ).

I n many s p e c i e s t h i s r e g io n a p p a r e n t l y c o n t a i n s un­

d i f f e r e n t i a t e d xylem and phloem c e l l s a s w e ll a s i n i t i a t i n g
cam bial c e l l s ( 1 4 ,4 3 ) .
The f i r s t i n d i c a t i o n o f s p r i n g a c t i v i t y i s a s w e llin g
o f t h e cam bial c e l l s i n a r a d i a l d i r e c t i o n .

The c e l l s , a t

t h i s tim e , may become alm o st dou ble t h e i r dorm ant w id th (14).
T h is s w e llin g h a s been r e p o r t e d to o c c u r s e v e r a l weeks be­
f o r e a c tu a l c e l l d iv is io n

t a k e s p l a c e ( 1 4 ,3 0 ,4 3 ,6 6 ) .

The

r a d i a l w a l l s become v e r y t h i n d u rin g t h e s w e l l i n g p h a se , e s­
p e c i a l l y In t h o s e r e g i o n s where t h e new t a n g e n t i a l w a lls
w i l l e v e n t u a l l y be a t t a c h e d ( 5 0 ).

C e ll c o n t e n t s change from

a g e l - l i k e s t a t e t o a s o l - l i k e s t a t e , becoming s e m i - f l u i d
and l e s s d e n s e ly g r a n u l a r ( 4 3 ,5 8 ,6 6 ) .
D uring t h e s w e llin g o f t h e cam bial r e g io n some u n d i f ­
f e r e n t i a t e d xylan. and phloem c e l l s , from t h e p r e v io u s y e a r» s
grow th , s t a r t to d i f f e r e n t i a t e ( 4 3 ) .

C e ll d i v i s i o n b e g in s

32
s e v e r a l weeks a f t e r t h e cam bial r e g io n s t a r t s to s w e l l .

Xy-

lern and phloem c e l l s a p p a r e n t ly a r e formed a t a b o u t t h e same
tim e w ith more xylem th a n phloem b e in g p ro d u c e d (14,30) .
C e ll fo r m a tio n i s v e r y r a p i d a t f i r s t and t h e cambium p r o ­
d u c e s c e l l s f a s t e r t h a n th e y can d i f f e r e n t i a t e ,

c a u s in g a

r a t h e r wide band o f u n d i f f e r e n t i a t e d c e l l s w ith t h i n w a l l s
on b o th s i d e s o f t h e i n i t i a t i n g l a y e r ( 1 4 , 6 6 ,7 2 ) .
Towards t h e end o f t h e growing s e a s o n , cam bial a c t i v i t y
slows down and e v e n t u a l l y t e r m i n a t e s .

Brown (14) o b se rv e d

t h a t xylem fo rm a tio n i n w h ite p in e had c e a s e d by Septem ber
26.

L ad e fo g ed (43) r e p o r t e d t h a t c e s s a t i o n o f wood form a­

t i o n v a r i e d g r e a t l y among d i f f e r e n t s p e c ie s , some fo rm ing
WDod u n t i l Septem ber, b u t many form ing v e ry l i t t l e o r none
a f te r Ju ly .
M a t u r a ti o n o f p r e v i o u s l y formed c e l l s c o n tin u e s f o r
ab o u t a month a f t e r cam b ial d i v i s i o n c e a s e s ( 7 2 ) .

E v e n tu a l­

l y o n ly a few c e l l s on e i t h e r s i d e o f t h e i n i t i a t i n g l a y e r
re m a in u n d i f f e r e n t i a t e d .

As t h e t r e e goes i n t o t h e dormant

c o n d i t i o n , t h e w a l l s o f t h i s l a y e r o f cam bial i n i t i a l s and
u n d i f f e r e n t i a t e d c e l l s become firm and r e l a t i v e l y t h i c k (30,
43) .
The r e l a t i o n betw een cam bial a c t i v i t y and t h e s l i p p i n g
o f b a rk i n t h e s p r i n g h a s been r e p o r t e d by many i n v e s t i g a ­
t o r s ( 1 6 ,3 0 ,5 8 ,7 2 ) .

Both cam bial a c t i v i t y and b ark s l i p p i n g

o c c u r w ith a r i s e i n te m p e r a tu r e .

Wilcox (7 2) d eterm in ed

33
t h a t b a rk s l i p p i n g o c c u r r e d on t h e t r u n k s o f e i g h t s p e c i e s ,
i n New York S t a t e , a f t e r t h e mean w eekly te m p e r a tu r e had
p a s s e d 40 d e g re e s F a h r e n h e i t .

T his b a rk s l i p p a g e p re c e d e d

a c t u a l c e l l d i v i s i o n by abo ut one m onth.

He a l s o r e p o r t e d

t h a t p e e l i n g r e s i s t a n c e was a t a minimum d u rin g t h e p e r io d
o f g r e a t e s t cam bial c e l l d i v i s i o n .

He concluded from t h i s ,

t h a t a lth o u g h cam bial d i v i s i o n was n o t a re q u ir e m e n t f o r
p e e l i n g , i t d id h e lp m a t e r i a l l y .

P e e l i n g was o b s e rv e d to

c o n tin u e f o r a b o u t one month a f t e r c e l l d i v i s i o n had sto p p e d
b u t w ith a g r a d u a l i n c r e a s e i n r e s i s t a n c e .

Esau (30) ob­

s e r v in g t h e t h i n - w a l l e d c o n d i t i o n o f t h e cambium b e f o r e and
d u rin g c e l l d i v i s i o n c o n c lu d e d a s f o llo w s :
The o b v io u s r e s u l t o f t h i s weakness o f t h e r a d i a l w a l l s ,
d u r in g t h e e a r l i e r and l a t e r s t a g e s o f cam bial a c t i v i t y ,
i s t h e s l i p p i n g o f t h e stem b a rk t h a t i s e a s i l y indu ced
by m e c h a n ic a l means when s p r i n g growth b e g i n s .
A ccording to W ilcox (72) , a t t h e c l o s e o f t h e growing
s e a so n t h e ca m b ial c e l l s h a r d e n i n t o t h e dormant c o n d i t i o n ,
and t h e cambium becomes r e s i s t a n t to r u p t u r i n g .

As a r e ­

s u l t t h e r e s i s t a n c e o f t h e t r e e to p e e l i n g i n c r e a s e s .

Va-Pious R esp onses o f Some P l a n t s When T r e a te d
With C hem icals
Some o f t h e f i r s t t h i n g s n o te d ab o u t t h e 2,4-D com­
pounds w ere th e s e l e c t i v i t y o f t h e c h o n ic a l f o r d i f f e r e n t
s p e c i e s o f p l a n t s , and t h e v a r i a t i o n i n ty p e s o f re s p o n s e

34
b ro u g h t a b o u t i n d i f f e r e n t p l a n t s and d i f f e r e n t p a r t s o f t h e
same p l a n t .

Hamner and Tukey (35) o b s e rv e d t h a t i n some

p l a n t s t h e growing t i p s w ere k i l l e d w h ile i n o t h e r p l a n t s
t h e y w ere m e re ly a r r e s t e d .

Some p l a n t s showed a d i s t i n c t

upward c u r v a t u r e o f t h e v a r i o u s o rg a n s (hyp onasty) w h ile
o t h e r s d'OnoniStrated a downward c u r v a t u r e ( e p in a s ty ) .

Some

stem s w ere fou nd to s t i f f e n and s p l i t w hereas some u n d e r­
ground p a r t s assumed a t y p i c a l w a te r-s o a k e d a p p e a ra n c e .

Va­

r i o u s t i s s u e s o f t e n showed a te n d e n c y to w ard s p r o l i f e r a t i o n ^
The t r a n s l o c a t i o n o f 2 ,4 -D i n p l a n t s h a s been i n v e s t i ­
ga ted by many w o rk e rs .

D h illo n and L ucas (24) o b s e rv e d t h a t

2 ,4 -D a p p l i e d to t h e s o i l was a b s o rb e d by t h e r o o t s and
t r a n s l o c a t e d upw ards, p r o b a b ly by th e xylean.

When t h e chem­

i c a l was a p p l i e d to t h e l e a v e s , t r a n s l o c a t i o n was downward
and was th o u g h t to t a k e p l a c e i n t h e phloem o r o t h e r l i v i n g
t i s s u e s , w ith some p o s s i b l y moving th ro u g h xylem c e l l s .

The

chem ical was found i n v a r i o u s o rg a n s o f t h e tomato p l a n t 26
days a f t e r b e in g a p p l i e d to d e c a p i t a t e d ste m s.
M i t c h e l l and Brown (51) found t h a t when 2,4-D was ap­
p l i e d to t h e l e a v e s o f b ean p l a n t s , t r a n s l o c a t i o n o f t h e
chem ical was c l o s e l y a s s o c i a t e d w ith t h e t r a n s l o c a t i o n o f
foo d m a t e r i a l s and was c o n fin e d to l i v i n g c e l l s .

Mien th e

a c i d was a p p l i e d to t h e r o o t s , i t was found to move through
t h e n o n - l i v i n g c e l l s o f t h e stem .

S u n l ig h t ap p e ared to h a s ­

te n th e tr a n s lo c a tio n o f th e stim u lu s.

Wea v e r and De Hose

35
(70) a ls o fo u n d a r e l a t i o n s h i p betw een t h e movement o f t h e
chem ical and t h e movement o f s y n t h e s i z e d c a r b o h y d r a t e s .
T here were i n d i c a t i o n s t h a t m ore u l t i m a t e damage r e s u l t e d
w ith v e r y r a p i d t r a n s l o c a t i o n .
A ccording to Tukey e t a l .

(67) t h e l e a v e s o f bindweed

y e llo w e d w i t h i n f i v e days a f t e r t h e a p p l i c a t i o n o f 2 , 4-D.
They o b s e rv e d t h a t sev en days a f t e r t r e a t i n g , t h e c e l l s o f
t h e u p p e r and lo w e r p a l i s a d e l a y e r s , and t h e m eso p h y ll had
l o s t t h e i r dense c o n t e n t s and h ad become c o n t r a c t e d , n arro w ,
and i r r e g u l a r i n shape*

The r e s p o n s e o f t h e stem was v a r i e d ;

cambium and phloem, 'when o b se rv e d seven days a f t e r t r e a t i n g ,
a p p e a re d to be g r e a t l y s t i m u l a t e d .

The phloem was r e p o r t e d

a s h a v in g a 66 p e r c e n t i n c r e a s e i n w id th i n t h e r a d i a l d i r e c ­
t i o n , and t h e cambium as b e in g doubled i n r a d i a l w id th .
T here was l i t t l e o r no r e s p o n s e n o te d i n t h e xylom.
Watson (68,69) r e p o r t e d t h a t when v e r y young bean p l a n t s
and v e l v e t b e n t g r a s s p l a n t s were s u b j e c t e d to 2,4-D t r e a t ­
m en ts, t h e im m ature, d e v e lo p in g l e a v e s became f i l l e d w ith
f,r e p l a cement t i s s u e . "

T h is t i s s u e had t h i c k e r - w a l l e d c e l l s

th a n w ere n o rm a lly fo u n d i n t h e p a l i s a d e l a y e r o r spongy
m e s o p h y ll; th e c h l o r o p l a s t s were e i t h e r a b s e n t o r a b o r t i v e
and t h e c e l l s h ad assumed odd sh a p e s, n o t a t a l l re se m b lin g
norm al t i s s u e .

I t was fo u n d t h a t c e l l s which had a l r e a d y
*

d i f f e r e n t i a t e d i n t o p a l i s a d e o r m eso p h y ll c e l l s d id n o t r e ­
v e r t to ’’re p la c e m e n t t i s s u e " b u t t h o s e c e l l s which had n o t

56
dev elo p ed p r i o r to t h e a p p l i c a t i o n o f t h e a c i d d i d .
t i s s u e was r e p o r t e d by Earnes (25) i n n u t g r a s s .

S i m i la r

B e sid e s an

i n c r e a s e d t h i c k n e s s i n t h e l e a f b la d e , cau sed by " r e p l a c e ­
m ent t i s s u e , " h e o b s e r v e d a p r o l i f e r a t i o n and s p l i t t i n g o f
t h e o u t e r t i s s u e s o f t h e eorm.
Hamner and Tukey (36) o b s e rv e d t h e e f f e c t s o f 2 ,4 -D on
s e v e r a l s h r u b s , v i n e s , and t r e e s and fo u n d a v a r i e t y o f r e ­
spon ses to t h e chem ical among th e d i f f e r e n t p l a n t s .

They

r e p o r t e d t h a t warmer w e a th e r a p p e a re d to a i d t h e chem ical i n
i t s to x ic e f f e c t s .

P l a n t s t r e a t e d when t h e te m p e ra tu r e was

81 d e g re e s F a h r e n h e i t w ere i n j u r e d much more q u ic k ly t h a n
th o s e t r e a t e d when t h e te m p e r a tu r e was 55 d e g r e e s .

They ob­

s e rv e d t h a t t h e b a rk o f a 4 0 -f o o t p o p l a r t r e e , which had
been t r e a t e d by a p p ly in g a s a l v e o f 2,4-D to h a t c h e t c u t s i n
th e t r u n k , began s p l i t t i n g above t h e p o i n t o f a p p l i c a t i o n
one month a f t e r t r e a t i n g .

They f u r t h e r n o te d t h a t t h e s p l i t ­

t i n g was caused by a p r o l i f e r a t i o n i n th e re g io n o u t s i d e t h e
cambium.

T his r e g i o n d ev eloped a fo rm a tio n o f s o f t , spongy,

new t i s s u e f i v e - e i g h t h s o f an i n c h t h i c k .

P each t r e e s

t r e a t e d i n a s i m i l a r m anner develop ed s m a ll, d i s c o l o r e d
s p o ts on t h e lim b s , from which gum exuded f r e e l y .

T h is exu­

d a t i o n was th o u g h t to be caused by an i n c r e a s e d a c t i v i t y o f
th e c e l l s o u t s i d e t h e cambium, vdiich cau sed a flo w o f gum.
I t was n o te d t h a t t r e e s i n shaded a r e a s resp o n d ed much more
slo w ly th a n t r e e s i n d i r e c t s u n l i g h t .

37
A ccording to Arend (5) t h e t r u n k s o f oak t r e e s c ra c k e d
and r u p t u r e d , fo rm ing c a l l u s - l i k e gro w th s due to t h e hormone
a c t i o n o f 2 ,4 , 5 - T .

However, t h e h a r k , i n g e n e r a l , rem ained

tig h t.
E h rh a rd t (27) w orking w ith sodium a r s e n i t e r e p o r t e d t h a t
t h e l e n g t h o f tim e e l a p s i n g betw een t r e a t m e n t and t h e f i r s t
e f f e c t s on t h e t r e e , v a r i e d g r e a t l y among d i f f e r e n t s p e c i e s .
He n o te d t h a t w ith t h e w i t h e r i n g o f t h e f o l i a g e , t h e b ark
became t i g h t , r e g a r d l e s s o f t h e norm al c o n d i t i o n s a t t h e
tim e , and rem ained t h a t way f o r v a r y in g p e r i o d s o f tim e , de­
p en d in g on t h e s p e c i e s .

Oake and e v e rg re e n s showed b ark

s e p a r a t i o n by t h e end o f t h e f i r s t grow ing s e a so n , b u t bark
on many o t h e r s p e c i e s rem ained i n a t i g h t c o n d i t i o n u n t i l
th e fo llo w in g s p rin g .
A nato m ical m o d i f i c a t i o n s o c c u r r in g i n t h e Stems o f r e d
s p ru c e and y e l l o w b i r c h , which had been t r e a t e d w ith e i t h e r
sodium a r s e n i t e o r sodium m o n o c h lo ro a c e ta te , have been r e ­
p o r t e d by G iro la m i ( 3 1 ) .

H is o b s e r v a t i o n s were b a se d on

sam ples c o l l e c t e d e i g h t days a f t e r t r e a tm e n t and ta k e n J u s t
above t h e p o i n t o f chem ical a p p l i c a t i o n .

T re atm e n ts had

been made b e f o r e t h e s a p - p e e l i n g sea so n , d u rin g t h e sap p e e l i n g , and a f t e r t h e s a p - p e e l i n g se a so n .

H is o b s e r v a t i o n s

made on b i r c h sam ples which had been t r e a t e d d u rin g t h e s a p p e e l i n g s e a so n were a s fo llo w s :
1.

The cambium o f sodium a r s e n i t e and sodium mono-

38
c h l o r o a c e t a t e - t r e a t e d sam ples had c o l l a p s e d .
2.

Most r e c e n t l y fonn ed xylem c e l l s o f a r s e n i t e t r e a t e d sam ples had c o l l a p s e d , c a u s in g t h e form a­
t i o n o f l a r g e la c u n a e betw een t h e xylem and cam­
bium.

The same e f f e c t s w ere n o te d i n t h e sam ples

which had been t r e a t e d w ith sodium m onochloroace­
t a t e b u t damage was n o t a s e x t e n s i v e .
3.

A p a r t i a l c o l l a p s e o f im m ature phloem c e l l s had
ta k e n p l a c e i n t h e a r s e n i t e - t r e a t e d sam p les.

Some

d i s t o r t i o n was e v i d e n t i n t h e f u n c t i o n i n g phloem.
A ll s i e v e t u b e s showed an e x c e s s iv e d e p o s i t i o n o f
c a l l u s (which i s u s u a l l y c o n s id e r e d to be a s i g n o f
d e c re a s e d f u n c t i o n ) .

The r e s u l t s were t h e same f o r

t h e sam ples t r e a t e d w ith sodium mono c h lo ro a c e t a t e
b u t a g a in were n o t as pro n o u n ced .
Popp e t a l .

(57) a l s o co n d u cted a n a to m ic a l s t u d i e s on

a rse n ite -tre a te d tre e s .

T h e ir r e p o r t was c o n fin e d to t h e

r e s u l t s o b t a i n e d on b la c k c h e rry t r e e s .

T re atm en ts were

made d u rin g J u l y and sam ples c o l l e c t e d s i x days l a t e r from
th e tru n k .

They r e p o r t e d t h a t p a r t i a l l y d i f f e r e n t i a t e d

c e l l s o f t h e xylem , cambium, and phloem ap p e a re d to be p l a s m olyzed and showed c o l l a p s e .

The c o n t e n t s o f t h e s ie v e

t u b e s o f t r e a t e d t r e e s were o b se rv e d to be more d a r k ly
s t a i n e d th a n t h e c o n t e n t s o f s i e v e tu b e s from n o m a l t r e e s .

59
They i n t e r p r e t e d t h i s d a rk e n in g a s "being caused by d is o r g a n ­
i z a t i o n o f t h e s i e v e tu b e c y to p la sm .

IV.

EXPERIMENTAL PROCEDURE

L o c a tio n and m ark in g o f t r e e s .

Most o f t h e f i e l d work

f o r t h i s s tu d y was c a r r i e d o u t a t t h e Dunbar E o r e s t E x p e ri­
m ent S t a t i o n , S a u l t S t e . M a rie , M ic h ig a n .

A t o t a l o f 361

tr e m b lin g asp e n , P o p u lu s t r e m u lo id e s M ic h x ., were t r e a t e d on
t h i s a r e a d u rin g t h e summer o f 1952.

E ifte e n a d d itio n a l

t r e e s w ere t r e a t e d i n t h e s p r in g o f 1955 a t t h e je n n i s o n
E o r e s t , l o c a t e d a b o u t 14 m i le s w est o f L a n s in g , M ich ig an .
Tree s i z e s ra n g ed from 4 to 12 in c h e s in d ia m e te r a t
b r e a s t h e i g h t , t h e m a j o r i t y b e in g from 6 to 8 i n c h e s .

M etal

t a g s , b e a r in g l e t t e r s and num bers, f a s t e n e d w i t h z i n c - c o a t e d
n a i l s , ivere u s e d to i d e n t i f y t r e e s s e l e c t e d f o r t r e a t i n g .
Each t r e e was th e n b la z e d w ith an axe to f a c i l i t a t e r e l o c a ­
tio n .
M ethods u s e d to a p p ly c h e m ic a ls .

A ll c h e m ic a ls were

a p p l i e d to t h e stem s o f t h e t r e e s by one o f t h r e e m ethods:
(1) a f r i l l g i r d l e fo llo w e d by s p ra y in g d i r e c t l y i n t o t h e
frill;

(2) a p e e le d g i r d l e fo llo w e d by s p ra y in g on t h e

p e e l e d s u r f a c e ; and (5) a b a s a l s p ra y a p p lie d d i r e c t l y to
th e b ark .
The f r i l l g i r d l e was formed by making a s e r i e s o f o v e r­
l a p p i n g axe c u t s aro u n d t h e e n t i r e c irc u m fe re n c e o f t h e
t r e e , a p p ro x im a te ly 18 in c h e s above t h e ground.

The c u t s

41
w ere made th ro u g h t h e b a rk and i n t o t h e sapwood f o r a d ep th
o f about o n e - h a lf in c h .

The ax e -h ead was p r e s s e d downward,

w hile/ in t h e t r e e , c a u s in g t h e b a rk and c u t p o r t i o n o f t h e
sapwood to be p r i e d away, and fo rm in g a cru d e r e s e r v o i r
around t h e t r e e stem .

The chem ical s o l u t i o n was th e n

s p ra y e d i n t o t h e f r i l l u n t i l th e r e s e r v o i r o v e rflo w e d , s a t ­
u r a t i n g t h e lo w e r p o r t i o n o f t h e t r e e t r u n k .
The p e e le d g i r d l e was made by removing a s t r i p o f b a rk ,
8 to 10 in c h e s w ide, from around t h e t r e e t r u n k , w ith t h e
lo w e r edge o f t h e g i r d l e abo ut 18 i n c h e s from t h e g ro u n d .
I n m aking t h i s g i r d l e , an axe and b a rk spud w ere employed i n
such a m anner t h a t t h e sapwood was n o t i n j u r e d .

The chem­

i c a l was th e n s p ra y e d d i r e c t l y on t h e p e e le d a r e a u n t i l t h e
s o l u t i o n r a n down t h e lo w e r p o r t i o n o f t h e t r u n k .
The t h i r d m ethod o f t r e a t i n g was t h e b a s a l s p ra y m eth­
od.

I n t h i s ty p e o f t r e a tm e n t , t h e chem ical was sp ray e d on

t h e b a s a l p o r t i o n o f t h e t r e e t r u n k w ith o u t any p re v io u s
p r e p a r a t i o n h a v in g been made.

The t r e e s were s p ra y e d from

t h e ground to a p o i n t a p p ro x im a te ly 30 in c h e s h i g h -,on t h e
tru n k .

The b a rk was s a t u r a t e d w ith s o l u t i o n , and s p ra y in g

was c o n tin u e d u n t i l t h e s o l u t i o n r a n down t h e b ark and
s t a r t e d to m o is te n t h e s o i l .
Hand s p r a y e r s , w ith a c a p a c i t y o f 2 g a l l o n s each, were
u sed to a p p ly th e c h e m ic a ls .

S e p a r a te , marked s p r a y e r s were

employed f o r each chem ical to p r e v e n t c o n ta m in a tio n .
s o l u t i o n s w ere mixed i n t h e s p r a y e r s .

The

42
The s o l u t i o n s w ere n o t a p p l i e d i n a c c u r a t e l y m easured
amounts b e c a u se i t was d e s i r e d to ap p ro ach a c t u a l t r e a t i n g
c o n d i t i o n s , such a s m ig h t be e n c o u n te re d i n com mercial p r a c ­
tic e .

However, an e f f o r t was made to t r e a t 10 t r e e s p e r

g a l l o n o f s o l u t i o n , r e g a r d l e s s o f t h e ty p e o f t r e a t m e n t
which h ad been u s e d .
M o d i f i c a t i o n s o f t h e t r e a t i n g m ethods d e s c r i b e d above
were employed on two o c c a s i o n s .

One group o f t r e e s was

t r e a t e d by p o u r in g v e ry sm all q u a n t i t i e s o f a sodium a r s e n ­
i t e s o l u t i o n i n t o t h e f r i l l e d g i r d l e s , which h ad been made
i n t h e u s u a l m anner.

A n o th er group o f t r e e s was t r e a t e d

w ith sodium mono c h lo ro a c e t a t e , which had been s p ra y e d i n t o
f r i l l g i r d l e s t h a t e x ten d e d o n ly h a l f way around t h e s t e m . /
Chemical s o l u t i o n s u s e d .

/

As s t a t e d p r e v io u s l y , t h r e e

ch e m ic a ls were u s e d i n t h e s e e x p e rim e n ts:

p r o p y le n e g ly c o l

b u t y l e t h e r e s t e r o f 2 , 4 - d ic h lo r o p h e n o x y a c e tic a c id (2,4-D
e s t e r ) , p ro p y le n e g l y c o l b u t y l e t h e r e s t e r o f 2 , 4 , 5 - t r i c h lo ro p h e n o x y a c e tic a c i d ( 2 ,4 ,5 - T e s t e r ) and sodium monoc h lo ro a c e ta te .
Hie 2 ,4 -D e s t e r was alw ays a p p l i e d as an o i l s o l u t i o n ;
number 2 d i e s e l o i l b e in g u se d a s t h e c a r r i e r .

The 2 ,4 ,5 - T

e s t e r was a ls o u s e d a s a d i e s e l o i l s o l u t i o n i n ev ery i n ­
s t a n c e e x c e p t one, i n which i t was a p p l i e d a s a w a te r emul­
sio n .

These two c h e m ic a ls were u s e d i n d i f f e r e n t c o n c e n tra ­

tio n s:

8 pounds a . h . g . ; 16 pounds a . h . g . ; and 24 pounds

43
a . h . g . ( a c i d e q u i v a l e n t p e r 100 g a l l o n s o f t r e a t i n g s o l u ­
tio n ) .
Sodium mono c h lo ro a c e t a t e was d i s s o l v e d i n w a te r and
u s e d i n s t r e n g t h s o f a p p ro x im a te ly 20 and 24 p e r c e n t , by
w e ig h t.

One group o f t r e e s was t r e a t e d w ith an em ulsion

made up by d i s s o l v i n g sodium m o n o c h lo ro a c e ta te i n o n e - h a l f
w a te r and o n e - h a l f d i e s e l o i l ;

t h e s t r e n g t h o f t h i s em ulsion

was a p p r o x im a te ly 27 p e r c e n t , by w e ig h t.
As a m a t t e r o f c u r i o s i t y , t h r e e groups o f t r e e s were
t r e a t e d w ith o t h e r c h e m ic a ls o r co m b in atio n s o f c h e m ica ls:
one group was t r e a t e d w ith a 5 p e r c e n t , by w e ig h t, s o l u t i o n
o f p e n ta c h lo r o p h e n o l i n d i e s e l o i l ;

a second group was

t r e a t e d w ith a s o l u t i o n c o n t a i n i n g eq u al p a r t s o f a 5 p e r ­
c e n t, by w e ig h t, p e n t a c h l o r o p h e n o l - d i e s e l o i l s o l u t i o n , and
an 8 pounds a . h . g . s o l u t i o n o f 2 ,4 ,5 - T e s t e r i n d i e s e l o i l ;
a t h i r d group was t r e a t e d w ith a 20 p e r c e n t s o l u t i o n , by
w e ig h t, o f sodium a r s e n i t e i n w a t e r . y 7
T re a tin g sc h e d u le .

T rees were t r e a t e d on seven d i f f e r ­

e n t d a t e s a t Dunbar; t h e e a r l i e s t d a te was Tune 4 and t h e
l a t e s t A ugust 1 1 .

The t r e e s , t r e a t e d on each o f t h e s e days,

w ere c o n s id e r e d to c o n s t i t u t e a t r e a t i n g s e r i e s ;

each s e r i e s

was made up o f a v a r y in g number o f t r e e g ro u p s; and each
group a v e ra g e d 10 t r e e s .

Each t r e e group o f a p a r t i c u l a r

s e r i e s r e p r e s e n t e d a d i f f e r e n t com b ination o f t r e a t i n g meth­
od and c h e m ic a l, a c c o rd in g to a p r e v i o u s l y co n ceiv ed p l a n .

44
One g a l l o n o f ch e m ica l s o l u t i o n was made up f o r each
group , and a s was s t a t e d p r e v i o u s l y , an e f f o r t was made to
t r e a t 10 t r e e s w ith i t .

However, when an u n u s u a l number o f

l a r g e t r e e s o c c u r r e d w i t h i n a g ro u p , i t som etim es was n o t
p o s s i b l e to t r e a t 10 t r e e s p e r g a l l o n and t h e group th e n
c o n ta in e d a l e s s e r number o f t r e a t e d t r e e s .

Groups seldom

c o n ta in e d m ore th a n 10 t r e e s b ec a u se , i f any s o l u t i o n was
l e f t o v e r a f t e r t h e t e n t h t r e e had been t r e a t e d , t h e group
was u s u a l l y sp ray e d l i g h t l y a second tim e t o u s e up t h e ex­
cess s o lu tio n in th e sp ra y e r.

Complete in f o r m a tio n r e l a t i v e

to t r e a t i n g m ethods and d a t e s o f a p p l i c a t i o n f o r each t r e e
t r e a t e d a t Dunbar can be fo u n d i n T able I .
Three t r e a t i n g d a t e s were employed d u rin g t h e s p r in g o f
1955 a t t h e l e n n i s o n F o r e s t ; t h e e a r l i e s t was A p r i l 24 and
t h e l a t e s t May 15.

Complete in f o r m a tio n r e g a r d in g th e s e

t r e a t m e n t s can be fou nd i n T ab le I I .
The c h e m ic a ls u s e d a t Dunbar w ere a ls o employed a t J e n n iso n .

The same c o n c e n t r a t i o n s and q u a n t i t i e s w ere u sed ex­

c e p t i n two i n s t a n c e s , viien r a t e s o f 20 t r e e s p e r g a l l o n and
40 t r e e s p e r g a l l o n w ere u s e d .

T r e a t in g methods Y^ere a lso

t h e same, e x c e p t t h a t no p e e le d g i r d l e s were u t i l i z e d .
A ll t r e a t m e n t s , a t b o th a r e a s , were made on c l e a r days
and no r a i n f e l l f o r a t l e a s t 24 h o u rs a f t e r t r e a t i n g ex cep t
on two o c c a s io n s :

on A ugust 11 a heavy r a i n , o f a p p r o x i­

m a te ly 3 h o u rs d u r a ti o n , f e l l s h o r t l y a f t e r t r e a t i n g was

45
TABLE I
SCHEDULE OF TREATMENTS MADE AT DUNBAR DURING 1952
(S means b a s a l sp ra y , F means f r i l l e d g i r d l e ,
and P means p e e le d g i r d l e . )
Tree numbers
w it h i n group

Chemical u s e d

S t r e n g th

Method

Number
tre e s
per
group

Ju n e 4 t r e a t m e n t s
D1-D13

2 ,4 ,5 -T e s te r

S

13b

20$, w t.

P

10

20$, w t.

F

10

20$, w t.
8# a . h . g .
8# a . h . g .
16# a . h . g .
8# a . h . g .

S
s
F
a
s

5
10
10
10
9

s

9

s
F
P

11
6
4

20$, w t.

P

9

20$, w t.
8# a . h . g .
8# a . h . g .
16# a . h . g .
8# a . h . g .

F
F
S
S
s

10
10
10
10
9

8# a . h . g . a

June 24 t r e a t m e n t s
3X1-IK10
IK11-IK20
IK21-IK25
IK26-IK55
IK36-IK45
RE46-EK55
BK56-IK64

Sod. mono c h lo r o a c e ta te
Sod. m onochloroa c e ta te
Sod. mono c h lo r o a c e ta te
2 ,4 ,5 - T e s t e r
2 ,4 , 5 - T e s t e r
2 ,4 ,5 - T e s t e r
2 ,4 -D e s t e r

June 25 t r e a t m e n t s
EK66-EK74
IK75-IK85
1X8 6 - IK 91
LK92-EK95

5$, w t.
P e n ta c h lo ro p h e n o l
P e n ta c h lo ro p h eno1
and 2 , 4 ,5 - T e s t e r 8# a . h . g .
—
NONE
NONE
J u ly 3 tre a tm e n ts

IX96-IK104
IK105-BEC114
IK115-IK1B4
IK125-IK134
3X13.5-. 1X144
1X145-1X155

Sod. m onochloroa c e ta te
So d . mono chlo ro a c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 ,5 -T e s t e r
2 , 4 ,5 - T e s t e r
2 ,4 -D e s t e r

/Y

46

TABLE I ( c o n tin u e d )

T ree num bers
w it h i n g ro up

Chemical u s e d

S tr e n g th

Method

------

J u ly 9 tre a tm e n ts
UEL-miO
IH11-EH19
DH20-IH29
DH30-DH39
IH40-EH49
DH50-IH59
IH60-IH69
LH70-IH79

Sod. m onochloroa c e ta te
Sod. mono c h lo ro a c e ta te
Sod. m onoch loro a c e ta te
2 ,4 fD e s t e r
2 ,4 -D e s t e r
2 ,4 ,5 - T e s t e r
2 ,4 ,5 -T e s t e r
2 ,4 ,5 - T e s t e r

Number
tre e s
per
group

27%, w t.

S

10°

20 %, w t.

F

9

20%, w t.
8# a . h . g .
16# a . h . g .
8# a . h . g .
16# a . h . g .
8# a . h . g .

P
S
S.
s
s
3?

10
10
10
10
10
10

s
F
S
s
F
S
s
p

10
10
10
10
10
10
1 07d
x

F

5e

24%, w t .

F

5f

24%, w t.
8# a . h . g .
8# a . h . g .

F
S
s

J u l y 15 t r e a t m e n t s
IH120-IH129
IH130-IH139
IH140-IH149
IH150-IH159
3E160-IH169
EH170-EH179
3H180-EH189
rHl90-IH196

2 ,4 -D e s t e r
2,4-rD e s t e r
2,4 -D e s t e r
2 ,4 ,5 -T e s t e r
2 ,4 ,5 -T e s t e r
2 , 4 ,5 - T e s t e r
2 , 4 ,5 - T e s t e r
2 ,4 ,5 -T e s t e r

8#
8#
16#
8#
8#
16#
24#
8#

a .h .g .
a .h .g .
a .h .g .
a .h .g .
a .h .g .
a .h .g .
a .h .g .
a .h .g .

August 11 t r e a t m e n t s
DJ5-DJ9
DJ10-DJ14
DJ15-DJ24
DJ25-DJ34
DJ35-DJ44

Sod. a r s e n i t e
Sod. m onochloroa c e ta te
Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 -D e s t e r

10
10
10

a Acid e q u i v a l e n t p e r 100 g a l l o n s o f t r e a t i n g s o l u t i o n .
^ One g a l l o n o f s o l u t i o n p e r t r e e group u n l e s s o t h e r ­
w is e s p e c i f i e d .
0 C a r r i e r was h a l f w a te r and h a l f d i e s e l o i l .
^ C a r r i e r was w a te r .
e About o n e - e i g h t h p i n t p e r t r e e ; p o u red i n t o f r i l l .
^ O n e - h a lf g a l l o n u s e d ; t r e e s f r i l l e d h a l f way around
stem .

47

TABLE I I
SCHEDULE OF ‘TREATMENTS MADE AT JMNISON DURING 1953
(S means b a s a l s p ra y and F means f r i l l e d g i r d l e . )
T ree numbers
w i t h i n group

Chemical u s e d

S tre n g th

Method

Humber
tre e s
per
group

A p ril 34 t r e a tm e n t s
J 9 5 -J9 6
J 9 7 -J9 8
199-1100

Sod. m onochloroa c e ta te
2 ,4 -D e s t e r
2 ,4 ,5 -T e s t e r

F
S
S

2a
2
2

S
S

1
1

F

1

20$, w t.

F

2°

20$, w t.

F

2d

20$, w t.

F

2

20$, w t.
8# a . h . g . 13
8# a . h . g .

May 8 t r e a tm e n t s
2 ,4 -D e s t e r
2 ,4 ,5 -T e s t e r
Sod. m onochioroa c e ta te

180
JS1
J82

8# a . h . g .
8# a . h . g .
20$, w t.

May 15 tr e a tm e n t s
170 & J 7 2
173 & 174
171 & 175

Sod. m onochloroa c e ta te
Sod. m onochloroa c e ta te
Sod. m o nochloroa c e ta te

a S o lu tio n a p p l i e d a t t h e r a t e o f 10 t r e e s / g a l l o n , un­
l e s s s p e c if ie d o th e rw ise .
A cid e q u i v a l e n t p e r
100 g a l l o n s o f t r e a t i n g s o l u t i o n .
0 S o l u ti o n a p p l i e d a t
d S o lu tio n a p p lie d a t

th e r a t e o f 40 t r e e s / g a l l o n .
t h e r a t e o f 30 t r e e s / g a l l o n .

48

com pleted; on A p r i l 24 a heavy r a i n f e l l a t n i g h t ,

sta rtin g

a b o u t 6 h o u rs a f t e r t r e a t i n g .
The t r e a t m e n t s a t Dunbar were made d u rin g a r a t h e r
heavy i n f e s t a t i o n o f t h e F o r e s t Tent C a t e r p i l l a r , Malacosoma
d i s s t r i a Hu b n .

Some o f t h e t r e e s w ere p a r t i a l l y d e f o l i a t e d

a t t h e tim e o f t r e a t m e n t ; o t h e r s were g e t t i n g a second s e t
o f l e a v e s which was n o t f u l l y d ev e lo p e d .
The A p r i l 24 t r e a t m e n t s a t J e n n is o n were made b e f o r e
bud b re ak ; t h e May 8 t r e a t m e n t s were made when t h e t r e e s
were b e g in n in g to l e a f o u t , and t h e May 15 t r e a t m e n t s made
when t h e l e a v e s w ere ab o u t t h r e e - q u a r t e r s d e v e lo p e d . /

/

/

C o l l e c t i o n o f sam ples f o r m ic ro s c o p ic s t u d y .

B efo re

any sam ples were c o l l e c t e d , t h e o b j e c t i v e s o f t h i s p h ase o f
t h e problem w ere l i s t e d , and i n d i v i d u a l c o l l e c t i o n s c h e d u le s
drawn up to o b t a i n t h e n e c e s s a r y m a t e r i a l .

I t was a p p a re n t

t h a t some sam ples c o u ld be u s e d f o r two o r m ore p u rp o s e s ,
t h u s r e d u c in g t h e t o t a l number o f sam ples r e q u i r e d .

A fte r

i n d i v i d u a l s c h e d u le s had been com pleted, a m a s t e r s c h e d u le
was drawn u p , from which a l l sam ples were o b t a i n e d .
B ecause o f t h e im p o rta n c e o f t h e t r e e s t a a I n t h e manu­
f a c t u r e o f p u lp and p a p e r , and becau se o f t h e s i g n i f i c a n c e
o f t h e cambium i n b ark p e e l i n g , t h e m a jo r em phasis o f t h i s
problem was p la c e d on t h e cam bial r e g io n o f th e t r e a t e d t r e e
stem .

A c c o rd in g ly , t h e f i r s t c o l l e c t i o n sch e d u le was de­

s ig n e d to s e c u re sam ples which would p ro v id e in f o r m a tio n

49
r e l a t i v e to t h i s p o r t i o n o f t h e t r e a t e d t r e e .
t i o n d e s i r e d was a s f o l l o w s :

The in fo rm a ­

(1) to d e te rm in e w h e th e r o r

n o t t h e a p p l i c a t i o n o f 2 ,4 -D e s t e r , 2 , 4 ,5 - T e s t e r o r sodium
mono c h lo ro a c e t a t e would c a u se any s t r u c t u r a l changes i n th e
cambium r e g i o n o f t h e t r e e stem s;

(2) i f changes d id o c c u r,

to d e te rm in e t h e p r o g r e s s i v e e f f e c t s o f each chem ical;
(3) to d e te r m in e , i f p o s s i b l e , t h e r e l a t i o n s h i p between
t h e s e p r o g r e s s i v e e f f e c t s and t h e lo o s e n i n g o f t h e b a r k ;
(4) to d e te r m in e which chem ical was m ost e f f e c t i v e i n l o o s ­
ening t h e b a rk ; and (5) to d eterm in e what th e e f f e c t would
be o f d o u b lin g t h e s t r e n g t h o f one o f t h e chem ical s o l u ­
tio n s.
F our t r e e s ,

s e l e c t e d from t h e June 24 t r e a t m e n t s , were

u s e d to o b t a i n t h e s e sam ples.
w ere u se d on t h e s e t r e e s :
frill;

The fo llo w in g f o u r tr e a tm e n t s

sodium mono ch lo ro a c e t a t e in a

2,4-D e s t e r i n a b a s a l s p ra y ; 2 ,4 ,5 - T e s t e r i n a b a s ­

a l s p ra y ; and a d o u b le s t r e n g t h s o l u t i o n o f 2 , 4 ,5 - T e s t e r i n
a b a sa l sp ray .

The f i r s t sam ples were c o l l e c t e d on J u l y 7

and a t a p p ro x im a te ly w eekly i n t e r v a l s t h e r e a f t e r u n t i l Sep­
tem ber 3.
Most sam ples were ta k e n from t h e t r e e stem a t a p p r o x i­
m a te ly 5 f e e t above t h e ground; a few were a ls o o b ta i n e d from
t h e sp ra y e d a r e a o f t h e stem (18 i n c h e s from t h e ground) ,
f o r com parison p u r p o s e s .

The c o l l e c t i o n s c h e d u le f o r t h e s e

sam ples i s p r e s e n t e d i n T ab le I I I .

50
TABLE I I I
SCHEDULE 0E STM SAMPLES TAKEN EROM TREES TREATED WITH THREE
DIEEERENT CHMICALS AND COLLECTED AT APPROXIMATELY WEEKLY
INTERVALS DURING THE SOMMER OE 1952
(T re e s w ere t r e a t e d on Ju n e 24, 1952.)
Sample
Number
IK -17-1S1
IK -27-1S
3K49-1S
IK -61-I S
IK -17-2S
IK-27-2&
IK -49-2S
IK -6 1 -2S
IK -17-3S
IK -27-3S
EK-49-3S
IK -17-4S
EK-27-4S
IK -49-4S
IK -61-3S
IK -17-5S
IK -27-5S
3K-61-4S
IK -17-6S
IK -27-6S
IK -49-5S

Chem ical used.

C o l l e c t i o n d a te

Days s i n c e
t r e a tm e n t

Sod. mono c h lo r o a c e ta te 2
2 ,4 ,5 -T e s te r
2 ,4 , 5 - T e s t e r 3
2 ,4 -D e s t e r

Ju ly
Ju ly
Ju ly
Ju ly

9
9
9
9

15
15
15
15

Sod. m on ochloroa c e ta te
2 ,4 ,5 - T e s t e r
2 ,4 ,5 -T e s t e r 3
2 ,4 -D e s t e r

Ju ly
Ju ly
Ju ly
Ju ly

17
17
17
17

23
23
23
23

Sod. mono c h lo r o a c e ta te
2 ,4 ,5 - T e s t e r
2 ,4 ,5 - T e s t e r 3

J u l y 24
J u l y 24
J u l y 24

30
30
30

Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s t e r 2 ,4 ,5 -T e s t e r 5
2 ,4 -D e s t e r

Ju ly
Ju ly
Ju ly
Ju ly

36
36
36
36

Sod. m onochloroa c e ta te
2 ,4 ,5 - T e s t e r
2 ,4 -D e s t e r

Aug. 8
Aug. 8
Aug. 8

45
45
45

Sod. m o nochloroa c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 , 5 - T e s t e r 3
2 ,4 -D
-

Aug.
Aug.
Aug.
Aug.

51
51
51
51

30
30
30
30

14
14
14
14

51
TABLE I I I (c o n tin u e d )
Sample
Number
IK -17-7S
JK-27-7S
IK -61-6S
EK-17-8S
IK -27-8S
IK -49-6S
IK -61-7S
IK -17-9S
IK -27-9 S
IK-49-7 S
IK -61-8S

C o lle c tio n d ate

Days s i n c e
t r e a tm e n t

So d .mo no chlo ro a c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 -D e s t e r

Aug. 20
Aug. 20
Aug. 20

57
57
57

Sod. m onochloroa c e ta te
2 ,4 ,5 - T e s t e r
2 , 4 ,5 - T e s t e r 3
2 ,4 -D e s t e r

Aug.
Aug.
Aug.
Aug.

27
27
27
27

64
64
64
64

Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s te r
2 ,4 ,5 -T e s t e r 3
2,4 -D e s t e r

S e p t.
S e p t.
S e p t.
S e p t.

3
3
3
3

71
71
71
71

Chemical u s e d

^-E xplanation o f sample numbers : Each sample was g iv en
a number a t t h e tim e o f c o l l e c t i o n , c o rre s p o n d in g to t h e
t r e e from w hich i t h ad been talcen. I n a d d i t i o n , ia s e t o f
l e t t e r s and num bers, f o llo w in g t h e t r e e number, was u se d to
d e s c r i b e how many ti m e s t h e t r e e had been sampled and t h e
p o r t i o n o f t h e t r e e u s e d . F o r example, DK-17-1S was u se d to
d e s c r i b e t h e sample t a h e n from t r e e IK-17 (See T ab le I) .
The " 1 ” f o llo w in g t h e second dash means t h a t i t was th e f i r s t
tim e t h a t t r e e IK-17 had been sampled; t h e S means t h a t i t
was a stem sam ple. The l e t t e r s L, B, and R w ere u s e d to d e s ­
i g n a t e l e a f , b ra n c h , and r o o t sam ples r e s p e c t i v e l y .
These
l e t t e r s o c c u r i n T able VI.

p

Sodium mono c h lo ro a c e t a t e was u s e d in c o n ju n c tio n w ith
a f r i l l e d g i r d l e ; 2 , 4 , 5 - T e s t e r and 2,4-D e s t e r were u s e d as.
a b asa l sp ray .
^A p p lied double s t r e n g t h (16# a . h . g . ) .

52

A second s e t o f stem sam ples, a ls o ta k e n a p p ro x im a te ly
5 f e e t above t h e g ro u n d , was o b t a i n e d to d e te r m in e t h e i n ­
f l u e n c e o f tim e o f t r e a tm e n t on t h e e f f e c t i v e n e s s o f each o f
t h e t h r e e c h e m ic a ls .

These sam ples w ere removed from t r e e s

t r e a t e d on d i f f e r e n t d a t e s , and i n each c a se t h e y were c o l ­
l e c t e d 36 days a f t e r t r e a t i n g .

T h is in f o r m a t i o n i s p r e s e n t ­

ed i n T able IV.
E ig h ty days a f t e r t r e a t i n g , one t r e e which h ad been
t r e a t e d w ith 2 ,4 ,5 - T e s t e r on June 4, was f e l l e d and stem
sam ples ta k e n a t 5 - f o o t i n t e r v a l s from t h e sp ray e d a r e a to
t h e to p o f t h e t r e e ;

th e p u rp o se o f t h i s sam pling was to de­

te rm in e i f t h e a c t i o n o f t h e chem ical was t h e same th ro u g h ­
out th e le n g th o f th e t r e e .

Branch and r o o t sam ples were

a l s o ta k e n from t h i s t r e e a t t h e same tim e , to d e te rm in e i f
t h e ch e m ical had caused any a n a to m ic a l changes i n t h e s e t r e e
p a rts.
S e v e n ty -o n e days a f t e r t r e a t i n g , r o o t sam ples were c o l ­
l e c t e d from t r e e EK-17, "which had been t r e a t e d w ith sodium
mono chloro a c e t a t e on June 24.

T h is was th e t r e e from which

stem sam ples had been ta k e n a l l summer, as p r e s e n t e d i n
T able I I I .
B ranch and l e a f sam ples were c o l l e c t e d th ro u g h o u t t h e
summer h e n d e f i n i t e s i g n s o f i n j u r y could be d e t e c t e d in
th e tr e e s .

No p a r t i c u l a r sc h e d u le was fo llo w e d i n t h e c o l -

53

TABLE IV
COLLECTION SCHEDULE OE STM SAMPLES TAKEN 56 DAYS
AFTER TREATING, FROM TREES WHICH HAD BEEN TREATED
ON VARIOUS DATES DURING 1952

Chem ical u se d

T reatm ent
d a te

C o lle c tio n
d a te

Days
sin c e
tre a t­
ment

Sod. m onochloroa c e ta te *
2 ,4 ,5 -T e s te r
2 ,4 -D e s t e r

June 24
Ju n e 24
Ju n e 24

J u l y 30
J u ly 30
J u l y 30

36
36
36

Sod. mono c h lo r o a c e ta te
2 ,4 ,5 - T e s t e r
2 ,4 -D e s t e r

Ju ly 3
Ju ly 3
Ju ly 3

Aug. 8
Aug. 8
Aug. 8

36
36
36

DH-58-1S
EH-58-1S

Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s te r
2,4 -D e s t e r

Ju ly 9
Ju ly 9
Ju ly 9

Aug. 14
Aug. 14
Aug. 14

36
36
36

IH -159-1S
IH -127-1S

2 ,4 ,5 -T e s t e r
2 ,4 -D e s t e r

J u l y 15
J u l y 15

Aug. 20
Aug. 20

36
36

Sample
number
DK-17-4S
IK -27-4S
DK-61-3S
IK -111-2S
IK -130-1S
DK-147-1S
DH-16-1S

* Sodium mono c h lo ro a c e t a t e was u s e d i n c o n ju n c tio n w ith
a f r i l l e d g i r d l e ; 2 ,4 ,5 - T e s t e r and 2,4 -D e s t e r were u s e d as
a b a s a l s p ra y .

54
l e c t i o n o f t h e s e sam p les, "because i t was n o t d e s i r e d to
s tu d y p r o g r e s s i v e e f f e c t s o f c h e m ic a ls on l e a v e s .
O th e r m i s c e l l a n e o u s stem sam ples were ta k e n d u rin g t h e
summer to o b t a i n a d d i t i o n a l in f o r m a tio n on t h e e f f e c t o f
c h e m ic a ls on t h e s t r u c t u r e o f t h e t r e e stem .

These sam ples

w ere n o t o b t a i n e d a c c o rd in g to a f i x e d s c h e d u le , b u t w ere
c o l l e c t e d a t any c o n v e n ie n t tim e .
T ab le V shows a l l th e sam ples c o l l e c t e d a t t h e Dunbar
S t a t i o n d u rin g t h e summer o f 1952.

Sample num bers, t r e a t ­

ment d a t e s , c h e m ic a ls and c o l l e c t i o n d a t e s a r e g iv e n .

It

s h o u ld be n o te d t h a t e v e ry tim e a sam ple was ta k e n from a
t r e a t e d t r e e , a c o rre s p o n d in g sample was o b ta in e d from an
u n tre a te d tr e e .

I n a d d i t i o n to t h e s e sam ples c o l l e c t e d a t

Dunbar, a d d i t i o n a l u n t r e a t e d sam ples were ta k e n from t h e
l e n n i s o n a r e a d u r in g 1953 and 1954 to p r o v id e com plete i n ­
fo rm a tio n on t h e c o n d i t i o n o f t h e cam bial r e g io n a t a l l s e a ­
sons o f t h e y e a r ; t h e s e sam ples a r e a ls o In c lu d e d i n Table V.
F ie ld o b s e rv a tio n s .

F i e l d o b s e r v a t i o n s were made a t

Dunbar th ro u g h o u t t h e summer o f 1952.

They were u s u a l l y

made a t t h e same tim e t h a t sam ples were c o l l e c t e d and w ere,
f o r t h e m ost p a r t , c o n f in e d to th e t r e e s b e in g sam pled.
These o b s e r v a t i o n s w ere made p r i m a r i l y on th e a p p e a ra n c e o f
l e a v e s , tw ig s and stem s o f t h e t r e e s .

I t was hoped t h a t

some c o r r e l a t i o n m ig h t be found between t h e o utw ard a p p e a r­
ance o f t h e t r e e and t h e i n t e r n a l , m ic ro s c o p ic changes o c-

"

55
TABLE V
COLLECTION SCHEDULE OP ALL SAMPLES TAKEN AT DONBAR DURING
1952 AND THE JENNISON AREA DURING 1953 AND 1954
(S means b a s a l s p r a y , P means f r i l l e d g i r d l e ,
and E means p e e le d g i r d l e . )
Sample
number
DUN-1-1S1
JX-1-1S
I K - E l- I S
EK-27-1S
DK-49-1S
IK -61-1S
JX-17-1S
DON-2 - I S
IK-15-3XB
DUN-3 -1 S
IK-17-ES
IK-E7-SS
DEC-49-2S
IK -61-28
D-1-1S
DUN-4 - 1 S
3K-17-3S
BEC-27-3S
DK-49-5S
DUN-5 -1 S
DUN-6-1SEL
DUN-7-1S
IK -17-4S
IK-S7-4S
DK-49-4S
DK-61-3S

Chemical u se d
U n tre a te d
Sod. mono chlo r o a c e ta te
Sod. mono c h l o r o a c e ta te
2 ,4 ,5 -T e s t e r
2 , 4 , 5 - T ester**
2,4-D e s t e r
Sod. m onochloroa c e ta te
U n tre ated
Sod. m onochloroa c e ta te
U n t r e a te d
Sod. mono chlo r o a c e ta te
2 ,4 ,5 - T e s t e r
2 ,4 ,5 -T e s t e r 2
2,4 -D e s t e r
2 ,4 ,5 -T e s t e r
U n tre a te d
Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 ,5 - T ester**
U n tr e a te d
U n tr e a te d
U n tre a te d
Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 ,5 - T e s t e r 2
2 ,4 -D e s t e r

T r e a t­
ment
d a te

Method
mm mm

C o lle c ­
tio n
d a te

Days
sin c e
tre a t­
ment

7 /1 /5 2

_ _

6 /2 4 /5 2

p3

7 /9 /5 2

15

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2

S
S
s

7 /9 /5 2
7 /9 /5 2
7 /9 /5 2
7 /9 /5 2

15
15
15
15

6 /2 4 /5 2

F

—

—

7 /9 /5 2
7 /9 /5 2

15
--

6 /2 4 /5 2
--

F

7 /9 /5 2
7 /1 7 /5 2

15

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /4 /5 2
---

F

7 /1 7 /5 2
7 /1 7 /5 2
7 /1 7 /5 2
7 /1 7 /5 2
7 /1 9 /5 2
7 /1 9 /5 2

23
23
23
23
45

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
--

F
s
s
—

7 /2 4 /5 2
7 /2 4 /5 2
7 /2 4 /5 2
7 /2 4 /5 2
7 /3 0 /5 2
7 /3 0 /5 2

30
30
30

s

—

S
S

s
s
—

—

-6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2

—

F
S
s
s

7 /3 0 /5 2
7 /3 0 /5 2
7 /3 0 /5 2
7 /3 0 /5 2

—

—

—
—
—

36
36
56
36

56
TABLE V (c o n tin u e d )
Sample
number
LK-111-1LB

Chemical u se d

Sod. m ono chloroa c e ta te
D—1—2SB
2 ,4 ,5 - T e s t e r
DUU-4-2SLB U n tr e a te d
Sod. m onochloroIK -17-5S
a c e ta te
IK -27-5S
2 ,4 ,5 -T e s t e r
2 ,4 - L e s t e r
BEC-61-4S
Sod. m onochloroIK -111-2S
a c e ta te
2 , 4 ,5 - T e s t e r
3K-130-1S
IK -1 4 7 -IS 2 , 4-D e s t e r
U n tre a te d
DUN-6-2S
Sod. m onochloroIK-17-6S
a c e ta te
IK -27-52
2 ,4 ,5 - T e s t e r
IK -49- 5S
2 , 4 ,5 - T e s t e r 2
2 ,4 -D e s t e r
3K-61-5S
Sod. m onochloroIH -16-1S
a c e ta te
2
,4
-D e s t e r
LB-38-1S
2 , 4-D e s t e r 2
LB-44-1S
2 ,4 ,5 - T e s t e r
3H-58-1S
U n t r e a te d
d o t - 6- 3 3
Sod. m ono chloroIK-6-1XB
a c e ta te
2 ,4 ,5 -T e s te r
IK-28-1XB
Sod. m onochloroIHB22-1LB
a c e ta te
2 ,4 -D e s t e r
IH-30-1LB
IH-52-1LB
2 ,4 ,5 - T e s t e r
LB-122-1LB 2 ,4 -D e s t e r
Sodium a r s e n i t e
DJ-8-1LB
Sod. M onochloroDJ-23-1LB
a c e ta te
U n tre ated
DOT-8-1LB
Sod. m ono chloro 3K-17-7S
a c e ta te
2 ,4 ,5 -T e s t e r
IK -27-7S

Days
s in c e
tre a t­
ment

Method

C o lle c ­
tio n
d a te

F
S
—

7 /3 0 /5 2
8 /5 /5 2
8 /5 /5 2

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2

F
S
S

8 /8 /5 2
8 /8 /5 2
8 /8 /5 2

45
45
45

7 / 3 /5 2
7 /5 /5 2
7 /3 /5 2

F
S
s

8 /8 /5 2
8 /8 /5 2
8 /8 /5 2
8 /8 /5 2

56
36
36

T re a t­
ment
d a te
7 /3 /5 2
6 /4 /5 2
—-

----

—-

27
62
—

—

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2

F
S
s
s

8 /1 4 /5 2
8 /1 4 /5 2
8 /1 4 /5 2
8 /1 4 /5 2

51
51
51
51

7 /9 /5 2
7 /9 /5 2
7 /9 /5 2
7 /9 /5 2

F

36
36
36
36

—

8 /1 4 /5 2
8 /1 4 /5 2
8 /1 4 /5 2
8 /1 4 /5 2
8 /1 4 /5 2

—

6 /2 4 /5 2
6 /2 4 /5 2

p
s

8 /1 8 /5 2
8 /1 8 /5 2

55
55

7 / 9 /5 2
7 /9 /5 2
7 /9 /5 2
7 /1 5 /5 2
8 /1 1 /5 2

p

8 /1 8 /5 2
8 /1 8 /5 2
8 /1 8 /5 2
8 /1 8 /5 2
8 /1 8 /5 2

40
40
40
34
7

8 /1 1 /5 2
—

F

8 /1 8 /5 2
8 /1 8 /5 2

—

6 /2 4 /5 2
6 /2 4 /5 2

F

8 /2 0 /5 2
8 /2 0 /5 2

57
57

----

s

s
s

s

s
s
F
—

S

7

57
TAHLE V ( co n tin u ed )
Sample
number

Chem ical u se d

IK -2 7-96
3K-49-7S
IK -61-8S
DUN-6-6SR

2 ,4 -D e s t e r
2 ,4 ,5 -T e s t e r
2 ,4 -D e s t e r
U n tre a te d
Sodium a r s e n i t e
Sod. m onochloroa c e ta te
2 ,4 ,5 - T e s t e r
U n tr e a te d
2 ,4 ,5 - T e s t e r
Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s t e r
2 ,4 ,5 - T e s t e r 2
2 ,4 -D e s t e r
U n tre a te d
Sodium a r s e n i t e
Sod. m onochloroa c e ta te
2 ,4 ,5 -T e s t e r
Sod. m onochloroa c e ta te
2 , 4 ,5 - T e s t e r
2 ,4 ,5 - T e s t e r 2
2 ,4 -D e s t e r
U n t r e a te d

J -8 9 -1 S
I-8 9 -2 S
I-8 9 -3 S
J -8 9 -4 S
I-8 9 -5 S
I- 8 9 - 6 S

U n tre a te d
U n tre ated
U n tr e a te d
U n tre a te d
U n tr e a te d
U n tre a te d

J -8 9 -7 S

U n tr e a te d

IK -61-6S
m -1 5 9 -lS
IH -127-1S
DDN-6-4S
DT-6-1S
DJ-22-1S
D-1-3SBR
DOT-4-3SBR
IH -58-2S
XK-17-8S
JX-27-8S
IK -49-6S
IK -6 1-7S
DUU-6-5S
DJ-6-2S
DJ-22-2S
JCE-159-2S
ZK-17-9SR

T re a t­
m ent
d a te

Method

6 /2 4 /5 2
7 /1 5 /5 2
7 /1 5 /5 2

S
s
s

——

-----

8 /1 1 /5 2

F

8 /1 1 /5 2
6 /4 /5 2

F
S

-----

7 /9 /5 2

s

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2

F
S
s
s

C o lle c ­
tio n
d a te
8 /2 0 /5 2
8 /2 0 /5 2
8 /2 0 / 5 2
8 /2 0 /5 2
8 / 2 0 /5 2
8 /2 0 /5 2
8 /2 3 /5 2
8 /2 3 /5 2
8 /2 3 /5 2

Days
sin c e
tre a t­
ment
57
36
36
—

9
9
80
....

45

8 /1 1 /5 2

If

8 /2 7 /5 2
8 /2 7 /5 2
8 / 2 7 /5 2
8 /2 7 /5 2
8 /2 7 /5 2
8 /2 7 /5 2

16

8 /1 1 /5 2
7 /1 5 /5 2

F
s

8 /2 7 /5 2
8 /2 9 /5 2

16
45

6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
6 /2 4 /5 2
--

F
S
s
s

9 /3 /5 2
9 /3 /5 2
9 /3 /5 2
9 /3 /5 2
9 /3 /5 2

71
71
71
71
-__

-----

-----

“ —

«...

- -

-----

—

4 /2 4 /5 3
5 /8 /5 3
5 /1 5 /5 3
5 /2 2 /5 3
5 /2 9 /5 3
6 /5 /5 3

-----

—

2 /1 8 /5 4

—_
—
----—

—
- -

64
64
64
64
——

—
—
——
——
—

-*-See f i r s t f o o t n o t e u n d e r T able I I I f o r e x p la n a tio n o f
sam ple num bers.
o

Double s t r e n g t h (16# a . h . g . ) .

58
c u rrin g in th e tr e a te d t r e e s .

I n a d d i t i o n to t h e s e g e n e r a l

o b s e r v a t i o n s , a d e t a i l e d i n s p e c t i o n o f e v e ry t r e a t e d t r e e
was made d u rin g t h e summer o f 195£; a n o t h e r was made d u rin g
t h e summer o f 1955.

These i n s p e c t i o n s n o te d t h e p e e l a b i l i t y

o f t h e b a rk as w e ll as t h e g e n e r a l a p p e a ra n c e o f t h e t r e e s .
F i e l d o b s e r v a t i o n s were a ls o made d u rin g 1953 and 1954
on t h e t r e e s w hich had been t r e a t e d a t t h e l e n n i s o n a r e a .
The p rim a ry p u r p o s e o f t h e s e o b s e r v a t io n s was to compare t h e
e f f e c t s o f v e r y e a r l y t r e a t m e n t s w ith th o s e a p p l i e d l a t e r i n
th e season.
I n o r d e r to make f u r t h e r o b s e r v a t i o n s , two i n s p e c t i o n
t r i p s , d u rin g t h e summers o f 1953 and 1954, were made to t h e
p r o p e r t i e s o f t h e P a t t e n Logging Company a t Amasa, M ich ig an,
and t h e W illiam B o n ifa s Lumber Company a t I r o n M ountain,
M ich ig an .

T hese companies were b o th c o n d u c tin g chem ical de­

b a r k in g e x p e rim e n ts on aspen, u s in g t h e same c h e m ic a ls as
were u s e d a t Dunbar.
M ethods o f sam ple rem o val.

Samples were removed from

t h e stem s and r o o t s o f t r e e s w i t h a s e t o f w ood-carvin g c h i s ­
e ls.

The c h i s e l s were o f an o r d i n a r y s q u a re -e d g e ty p e , and

a h o llo w , h a l f - r o u n d t y p e .

L e a f and tw ig sam ples were ex­

t r a c t e d w ith th e a i d o f a r a z o r - s h a r p s c a l p e l .
S in c e i t was d e s i r e d to s tu d y t h e cambium and a d ja c e n t
t i s s u e s o n ly , and b e c a u s e i t f a c i l i t a t e d sample rem oval, t h e
o u t e r p o r t i o n o f t h e b a rk was c a r e f u l l y removed w ith t h e

59
s q u a re -e d g e c h i s e l b e f o r e stem o r r o o t sam ples were e x t r a c t ­
ed ( s e e F ig . 1 ) .

A f t e r t h e o u t e r p o r t i o n o f t h e b a rk had

been removed, a r e c t a n g l e , m e a su rin g a p p r o x im a te ly o n e - h a l f
in c h wide and t h r e e - q u a r t e r s o f an in c h lo n g , was form ed by
c u t t i n g th ro u g h t h e phloem and cambium, i n t o th e o u t e r l a y ­
e r s o f t h e xylem .

T h is was acco m p lish ed by removing a num­

b e r o f v e r y t h i n l a y e r s o f m a t e r i a l w ith t h e h a l f - r o u n d
c h i s e l , a s shown i n F i g . 2.

A c le a n c u t was made th ro u g h

t h e o u te rm o s t grow th r i n g s by p l a c i n g t h e sq u a re -e d g e d c h i s ­
e l alo n g t h e p e r i m e t e r o f t h e r e c t a n g l e and p u sh in g t h e
b la d e i n to th e wood.

The c h i s e l was th e n p l a c e d d i a g o n a ll y

a c r o s s each c o r n e r o f t h e r e c t a n g l e and pushed in t o t h e
xylem form in g an o c ta g o n ( s e e F ig . 3 ) .

The s q u a re -e d g e

c h i s e l was th e n i n s e r t e d i n t h e groove which formed t h e b a s e
o f t h e o c ta g o n and p r e s s e d i n t o t h e wood, c a r e being ta k e n
t h a t i t was n o t p r e s s e d i n to o f a r .

The h a n d le o f t h e c h i s ­

e l was th en p u sh ed down, p r y i n g t h e sample o u t o f t h e t r e e ,
a s i l l u s t r a t e d i n F ig . 4 .

Each sample when removed c o n ta in e d

one o r two growth r i n g s as w e ll a s t h e cam bial r e g io n , fu n c ­
t i o n i n g phloem, and a t l e a s t a p o r t i o n o f t h e n o n - f u n c tio n in g
phlo em.
Small tw ig s , m e a su rin g between o n e - s i x t e e n t h and t h r e e s i x t e e n t h s :o'f an in c h i n d ia m e te r, were sampled by making
c le a n , c r o s s - s e c t i o n a l c u t s th ro u g h t h e tw ig s w ith a sh arp

F ig . 1 .

Showing m ethod o f rem oving o u t e r h a r k
o f a t r e e w ith a c h i s e l .

P h o to g ra p h th r o u g h t h e c o u r t e s y o f Fohn L . H i l l .

62

F ig . 2.

F o rm a tio n o f r e c t a n g l e by c u t t i n g th r o u g h
t h e phloem and i n t o t h e o u t e r l a y e r s
o f t h e x ylem .

P h o to g ra p h th ro u g h t h e c o u r te s y o f Jo h n L . H i l l .

64

F ig . 3 . F o rm a tio n o f o c t a g o n "by c u t t i n g a c r o s s
t h e c o r n e r s o f p r e v i o u s l y fo rm ed r e c t a n g l e .
P h o to g r a p h th r o u g h t h e c o u r t e s y o f Joh n L . H i l l .

66

F ig . 4.

.Method o f p r y i n g o u t sam ple composed o f p h lo em ,
cambium, and o u t e r m o s t r i n g s o f x y le m .

P h o to g ra p h th ro u g h t h e c o u r te s y o f Jo h n L . H i l l .

68
s c a lp e l*

The sam p les were a l l c u t to a p p ro x im a te ly t h r e e -

e i g h t h s o f an in c h i n l e n g t h .
The m i d - r i b p o r t i o n o f l e a v e s was sam pled by removing a
r e c t a n g u l a r p o r t i o n o f t h e l e a f b la d e which in c lu d e d t h e
m id -rib .

The r e c t a n g l e s were a p p ro x im a te ly t h r e e - s i x t e e n t h s

o f an in c h wide ( a t r i g h t a n g le s to t h e m i d - r i b ) , and o n eq u a r t e r o f an in c h lo n g ( p a r a l l e l w ith t h e m id - r ib ) .
When t h e sam ples were removed from t h e t r e e , th e y were
Im m ediately p l a c e d i n numbered b o t t l e s c o n t a in i n g FAA. k i l l i n g
and f i x i n g f l u i d made i n a c c o rd a n c e w ith t h e f o r n u l a g iv e n
by Jo h an sen (42) f o r woody t i s s u e s .

Upon r e t u r n i n g from t h e

f i e l d , t h e sam ples w ere t r a n s f e r r e d to t e s t tu b e s and a s ­
p i r a t e d by means o f a w a te r a s p i r a t o r u n t i l t h e y sank to t h e
bottom o f t h e t u b e s .

A s m a ll s t r i p o f w h ite c a rd b o a rd , w ith

t h e sample number w r i t t e n on i t w ith I n d i a in k , was p la c e d
i n each t e s t tu b e .
A 4 by 6 in c h f i l e c a rd was made o u t f o r each sample
c o l l e c t e d and a l l p e r t i n e n t in f o r m a tio n r e l a t i v e to t r e a t ­
in g , c o l l e c t i n g and s u b s e q u e n t h a n d lin g was re c o rd e d t h e r e ­
on.
S e c tio n in g and s t a i n i n g o f m a t e r i a l .

A ll m a t e r i a l was

embedded i n p a r a f f i n and mounted on wooden b lo c k s p r i o r to
s e c t i o n i n g ; t h e i d e n t i f y i n g number o f each sample was w r i t t e n
on t h e wooden b lo c k i n i n d i a in k .

69
A 3 by 5 in c h f i l e c a r d was th e n made o u t f o r each
sample when i t was s e c t i o n e d ; in f o r m a tio n r e l a t i v e t o t h i c k ­
n e s s o f s e c t i o n s , s t a i n i n g sc h e d u le fo llo w e d , and number o f
s l i d e s made was r e c o r d e d .
L e a f s e c t i o n s w ere c u t on a r o t a r y m icrotom e and a f ­
f i x e d to g l a s s s l i d e s by means o f Haupt* s a d h e s iv e .

Only

c r o s s s e c t i o n s w ere made o f l e a v e s and t h e y w ere a l l c u t 10
m ic ro n s t h i c k .
A ll o t h e r s e c t i o n s were made on a s l i d i n g m icrotom e and
were c u t betw een 8 and 14 m icro n s i n t h i c k n e s s .

C ross sec­

t i o n s and r a d i a l s e c t i o n s were c u t f o r a l l stem and r o o t
sam ples, and f o r some tw ig sam ples.

The s e c t i o n s were

p l a c e d between w ir e s c r e e n s , a s d e s c r ib e d by Hyland (40) to
p r e v e n t c u r l i n g and to e x p e d ite s t a i n i n g .

A ll wood s e c t i o n s

were s t a i n e d w ith s a f r a n i n and f a s t g re e n , and were made i n ­
to perm anent s l i d e s .

V.

FIELD OBSERVATIONS

The e f f e c t s o f ch em ical t r e a t m e n t on t r e e a p p e a ra n c e .
The f i r s t t r e a t m e n t s , in v o l v in g a l l t h e s ta n d a r d ch e m ica ls
and t r e a t i n g m eth o d s, w ere made on Ju ne 24 and Ju n e 25.
T h e r e f o r e , i n o r d e r to o b s e rv e t h e e f f e c t s o f t h e c h e m ic a ls
f o r t h e l o n g e s t p e r i o d o f tim e , m ost f i e l d o b s e r v a t i o n s were
made on t r e e s t r e a t e d on t h e s e d a t e s .
The f i r s t t r e e s to show s ig n s o f i n j u r y from chem ical
t r e a t m e n t were t h o s e which had been f r i l l e d and t r e a t e d w ith
sodium m o n o c h lo r o a c e ta te .

These t r e e s were t r e a t e d on June

24 and an i n s p e c t i o n made 15 days l a t e r .

A ll t h e l e a v e s

w ere t u r n i n g b la c k and m o st o f them had a d r i e d , d i s t o r t e d
a p p e a ra n c e .

The b a rk o f t h e s te n s was t u r n i n g a dark brown

Im m ediately above t h e f r i l l e d a r e a s .

None o f t h e o t h e r

t r e e s , t r e a t e d a t t h e same tim e , showed s i g n s o f i n j u r y .
T w e n ty -th re e days a f t e r t r e a t i n g i t was o b s e rv e d t h a t
a l l t r e e s t r e a t e d w i t h sodium mono c h lo ro a c e t a t e i n f r i l l s
w ere c o m p le te ly d e f o l i a t e d .

Stem b ark ap p e ared to be com­

p l e t e l y b la c k e n e d from t h e f r i l l s to a p o i n t about 5 f e e t
above t h e f r i l l s .

A few t r e e s w hich had r e c e iv e d a b a s a l

spray t r e a t m e n t o f 2 , 4 , 5-T e s t e r showed some e f f e c t s o f t h e
tre a tm e n t.

The l e a v e s were s t a r t i n g to d i s p l a y b r i l l i a n t

r e d and y e llo w c o l o r s ; sm all b rown and o r a n g e - c o l o r e d s p o t s

71
began to a p p e a r on t h e lo w e r 5 o r 6 f e e t o f t h e st©n b a r k .
No o t h e r t r e a t e d t r e e s a p p e a re d to be a f f e c t e d a t t h i s tim e .
O b s e r v a tio n s made 50 days a f t e r t r e a t i n g r e v e a l e d t h a t
t h e phloem and eam bial r e g io n s o f t r e e s , t r e a t e d w ith sodium
m o n o c h lo r o a c e ta te i n f r i l l s ,

a p p e a re d to be c o m p le te ly

k i l l e d b e n e a th

t h e l a r g e a r e a s o f b la c k e n e d b a r k .

a r e a s ex ten d ed

to a b o u t 5 f e e t above t h e f r i l l s

tim e .

These

at t h i s

I n c o n t r a s t t o t h i s c o n d i t i o n , t h e o n ly phloem and

eam bial t i s s u e s t h a t a p p e a re d dead on t r e e s t r e a t e d w ith
£ ,4 ,5 -T e s te r,

were c o n f in e d to sm a ll a r e a s

found b e n e a th

th e d is c o lo re d

s p o ts d e s c r ib e d p r e v i o u s l y . These

more num erous and l a r g e r th a n r e p o r t e d a t 23 d ay s.

s p o t s were
However,

e x t e n s i v e a r e a s o f g r e e n bark e x i s t e d between d i s c o l o r e d
s p o t s , and t h e phloem and eam bial r e g io n s b e n e a th t h e s e
g re e n a r e a s a p p e a re d to be h e a l t h y .

The f i r s t e v id e n c e o f

damage to t r e e s which had r e c e iv e d a b a s a l s p ra y o f 2,4-D
e s t e r was o b s e rv e d on t h i s d a te ; t h e e f f e c t s w ere v e r y sim­
i l a r to t h o s e prod uced by 2 ,4 ,5 - T e s t e r .
D e f o l i a t i o n o f t r e e s t r e a t e d w ith 2 ,4 ,5 - T e s t e r d id n o t
o c c u r u n t i l 45 days a f t e r tr e a tm e n t and was th e n o n ly t a k i n g
p l a c e on some o f t h e t r e e s .
be seen i n F ig u r e 5.

T h is d e f o l i a t e d c o n d i t i o n can

I t was n o te d a t t h i s tim e t h a t sodium

m o n o c h lo ro a c e ta te k i l l e d l e a v e s much more q u ic k ly th a n
e i t h e r 2 , 4 , 5 - T o r 2,4-D ; l e a v e s o f t r e e s t r e a t e d w ith sodium
mo no c h lo ro a c e t a t e had t u r n e d from g re en to b la c k w i t h i n a

72
few d a y s 1 tim e and had f a l l e n w i t h i n 25 d a y s .

The l e a v e s of

t r e e s t r e a t e d w ith 2 , 4 , 5 - T e s t e r had f i r s t tu r n e d a b r i l l i a n t
r e d o r y e llo w c o l o r and had rem ained on t h e t r e e s f o r a much
lo n g e r tim e .

At t h e tim e o f t h i s e x a m in a tio n some l e a v e s on

t r e e s t r e a t e d w ith 2 ,4 -D were s t i l l g re e n .

I t was a ls o

n o t e d t h a t t h e ston-w ood b e n e a th t h e d i s c o l o r e d p a t c h e s o f
2 ,4 ,5 - T t r e a t e d t r e e s , c o n ta in e d b la c k r i n g s o f t i s s u e ; t h e
r i n g s w ere s m a l l e r and were c o n ta in e d w i t h i n th e p e r i m e t e r s
o f th e d isc o lo re d a re a s .
F ig u r e 6.

These r i n g s a r e p l a i n l y v i s i b l e i n

I t was a l s o n o t e d a t t h i s tim e t h a t t h e sp ra y e d

a r e a o f ste m s, and t h e t i p s o f b ra n c h e s o f 2 ,4 ,5 - T t r e a t e d
t r e e s , were e v i d e n t l y i n an advanced s t a t e o f i n j u r y .

The

b r a n c h e s , between t h e t r e e tr u n k s and t h e b ra n c h t i p s , ap­
p e a r e d to be h e a l t h y ; t h e t r u n k s th e m se lv e s a p p e a re d to be
h e a l t h y from j u s t below t h e t i p s o f t h e l e a d e r s to a p o i n t
a b o u t 10 f e e t above t h e ground .

Between 5 and 10 f e e t above

t h e gro und, t h e o u t e r s u r f a c e o f t h e b ark seemed to be
g reen .

However, t h e phloem and eam bial r e g i o n s wTe r e ob­

s e rv e d to be t u r n i n g a l i g h t brown c o l o r .

Below 5 f e e t t h e

b a r k c o n ta in e d numerous d i s c o l o r e d p a t c h e s , and t h e sp ra y e d
a r e a o f t h e t r u n k s was t u r n i n g a s o l i d orange-brow n c o l o r .
T re e s t r e a t e d w it h 2,4-D e s t e r began to develop many
d i s c o l o r e d s p o t s on t h e lo w e r p o r t i o n o f t h e stems a t 51
days a f t e r t r e a t i n g .

These s p o ts were v e ry s i m i l a r to t h o s e

caused by 2 , 4 , 5 - T e s t e r .

As seen i n F ig u r e 7, t h e s e

73

b l o t c h e s w ere exuding a r e s i n o u s l i q u i d ,
t h e 2 ,4 -D t r e a t e d t r e e s .

e s p e c ia lly th o se o f

The l e a v e s o f t h e 2 ,4 -D t r e a t e d

t r e e s w ere now i n f u l l autumn c o lo r , w h ile t h o s e o f m ost o f
t h e 2 ,4 , 5 - T t r e a t e d t r e e s were b la c k e n e d and s h r i v e l l e d ; a
few were c o m p le te ly d e f o l i a t e d .

However, some o f t h e

2 . 4 .5 - T t r e a t e d t r e e s s t i l l r e t a i n e d numerous c o lo re d
le a v e s.

I t was a ls o n o t e d a t t h i s tim e t h a t a lm o st a l l

t r e e s which had b een t r e a t e d w ith a doub le s t r e n g t h s o l u t i o n
o f 2 ,4 ,5 - T e s t e r w ere c o m p le te ly d e f o l i a t e d , a lth o u g h t h e
e x t e n t o f damage to t h e stem bark seaned to b e ab o u t t h e
same a s t h a t on t r e e s t r e a t e d w ith s i n g l e s t r e n g t h .
T re e s t r e a t e d w ith sodium mono c h lo ro a c e t a t e a p p l i e d to
a p e e le d g i r d l e f i r s t d is p la y e d s i g n s o f i n j u r y 55 days a f t ­
e r t r e a t m e n t ; t h e l e a v e s o f some t r e e s w ere t u r n i n g a brown­
is h c o lo r.

At t h e same tim e , i t was o b se rv e d t h a t t h e b a rk

c o u ld e a s i l y be s t r i p p e d , f o r ab o u t a f o o t , above t h e
f r i l l e d a r e a s o f t r e e s t r e a t e d w ith t h i s ty p e g i r d l e and
sodium mono c h lo ro a c e t a t e .
At 62 days a f t e r t r e a t i n g , t h e d i s c o l o r e d s p o ts on
2 .4 .5 - T t r e a t e d t r e e s had sp re a d a l l o v e r t h e stem , from t h e
ground to t h e crown; i n many p l a c e s th e y were c o a le s c e d ,
fo rm in g l a r g e a r e a s o f o r a n g e - c o l o r e d b a rk .

However, a r e a s

o f g re e n b ark c o u ld s t i l l be seen on m ost t r u n k s .
o f m ost b ra n c h e s were c o m p le te ly k i l l e d ,

The t i p s

and t h e p o r t i o n s

74
betw een t i p s and t r u n k s d i s p l a y e d an o ra n g e c o l o r s i m i l a r to
t h a t o f t h e stem .
The a p p e a ra n c e o f t r e e s t r e a t e d w ith 2,4-D was q u i t e
s i m i l a r t o t h o s e t r e a t e d w ith 2 ,4 ,5 - T , alth o u g h t h e d e g re e
o f damage was much l e s s s e v e r e .

On t h e c o n t r a r y , t r e e s

which had been f r i l l e d and t r e a t e d w ith sodium m onochloroa c e t a t e were q u i t e d i f f e r e n t i n a p p e a ra n c e from e i t h e r t h e
2 ,4 -D o r 2 , 4 , 5 - T t r e a t e d t r e e s .

The stem b ark o f t r e e s

t r e a t e d w ith sodium mono c h lo ro a c e t a t e was now a s o l i d b la c k
c d l o r from t h e f r i l l s to t h e crowns.

On some t r e e s , g re e n

bark was s t i l l v i s i b l e , b u t i t was c o n f in e d to v e r y n arrow
v e r t i c a l s t r e a k s , som etim es e x te n d in g from t h e f r i l l s to t h e
to p s o f t h e t r e e s *

I t was seen t h a t m ost o f t h e b ark b e ­

tween f r i l l s and t h e ground was

s t i l l g reen .

An ex a m in a tio n made 71 days a f t e r t r e a t i n g showed t h a t
t h e b ark o f t r e e s which h ad been f r i l l e d and t r e a t e d w ith
sodium mono c h lo ro a c e t a t e c o u ld e a s i l y be s t r i p p e d o f f t h e
tr u n k , from t h e f r i l l s t o a h e i g h t o f a b o u t 7 f e e t above t h e
ground.

On many t r e e s t r e a t e d w ith 2 ,4 ,5 - T , v e ry l i t t l e

g re e n b ark c o u ld be fo u n d above t h e sp ra y e d a re a ; t h e
sp ra y e d a r e a i t s e l f h ad tu r n e d a s o l i d brown c o l o r .

I n most

c a s e s , t h e b a rk o f t h e s e t r e e s s t i l l r e s i s t e d p e e l i n g .
T re e s t r e a t e d w ith 2,4 -D w ere s i m i l a r i n ap p e aran c e to
2 ,4 ,5 - T t r e a t e d t r e e s b u t were n o t damaged a s much.

75
I t was i n t e r e s t i n g to n o t e t h a t a lth o u g h t r e e s t r e a t e d
w ith d oub le s t r e n g t h 2 ,4 ,5 - T had been d e f o l i a t e d more q u ic k ­
l y th a n t h o s e w ith s i n g l e s t r e n g t h s o l u t i o n s , t h e r e d id n o t
seem to be any d i f f e r e n c e i n a p p e a ra n c e o r p e e l a b i l i t y o f
t h e stem b ark a t t h i s tim e .

The r o o t s o f a l l t r e a t e d t r e e s

a p p a r e n t l y had n o t been damaged by t h e c h e m ic a l t r e a t m e n t s ,
even thou gh many o f t h e t r e e s ap p e a re d to be k i l l e d down to
th e ro o t c o lla r .
E ig h ty days a f t e r t r e a t i n g , t h e b ark o f t r e e s w hich had
been t r e a t e d w ith 2 , 4 , 5 - T on June 4, 1952, d i s p l a y e d an
o ra n g e and brown, v a r i e g a t e d c o l o r above t h e s p ra y e d a r e a s .
B ranches were b la c k e n e d f o r a d i s t a n c e o f a b o u t 8 in c h e s
back o f t h e t i p s ; t h e p o r t i o n s between t i p s and tr u n k s ex­
h i b i t e d a c o l o r a t i o n s i m i l a r to t h e stem .
can be see n i n F ig u r e 8 .

T h is c o l o r a t i o n

The b ark o f t h e sp ra y e d a r e a s was

a s o l i d brown c o l o r and co u ld be p e e le d o f f f a i r l y e a s i l y ;
b a rk above th e s p ra y e d a r e a s was s t i l l t i g h t and co uld n o t
be p e e l e d .

The r o o t s s t i l l seemed to be h e a l t h y , even imme­

d i a t e l y below t h e r o o t c o l l a r s .
E f f e c t i v e n e s s o f c h e m ic a ls and t r e a t m e n t s u s e d to f a ­
c i l i t a t e p e e lin g .

A summary o f a 100 p e r c e n t i n s p e c t i o n

made on Septem ber 5 can be fou nd i n T able V I.

The c o n d i t i o n

o f a l l t r e e s , t r e a t e d d u rin g t h e summer o f 1952, i s p r e s e n t ­
ed i n t h i s t a b l e .

C o n d itio n o f t r e e s was d e te rm in e d by a

c a r e f u l e x a m in a tio n o f l e a v e s and stem b a r k .

76
TABLE VI
SUMMARY OF INSPECTION MADE ON SEPTEMBER 5, 1953,
OF ASPEN TREATED DURING 1953
(S means b a s a l sp ra y , P means p e e le d g i r d l e ,
and F means f r i l l g i r d l e . )
T re atment
d a te
6 /4
6 /2 4

Group
D 1-D 13
EKI-UCIO

6 /2 4

DEC11-EK20

6 /2 4

IK 2 1 -IK 2 5

6 /2 4
6 /2 4
6 /2 4
6 /2 4
6 /2 4
6 /2 5

EK26-DEC35
IK 36-E K 45
IK 4 6 -3 K 5 5
EK 56-IE:64
E K 65-IK 74
IK 7 5 -3 K 8 5

6 /2 5
6 /2 5
7 /3

DN86-rK:90
IK 9 1 -IK 9 5
IK 9 5 -IK 1 0 4

7 /3

IK 1 0 5 -IK 1 1 4

7 /3
7 /3
7 /3
7 /3
7 /9

r K 1 1 5 -r K 1 2 4
IK 125-ISC 134
IK 155-D K 144
IK 1 4 5 -r sa 5 3
iH i-r e io

7 /9

m n -r H i9

7 /9

EH2 0 -IH 29

7/9
7/9

IH 3 0 -IH 3 9
E H 40-IH 49

Chemical u s e d

Number o f t r e e s
M e t h - -------------------------od rpl D ND I H

3 . 4 . 5-T e s t e r
Sod. m onochloroa c e ta te
Sod. mono c h lo ro a c e ta te
Sod. m onochloroa c e ta te
3 . 4 . 5-T e s t e r
3 . 4 . 5-T e s t e r
3 . 4 . 5-T e s t e r 2
3.4-D e s t e r
J e n t a c h lo r o p h e n o l
7> P e n ta c h lo ro p h e n o l:
i 3 , 4 , 5-T e s t e r
None
None
Sod. m onochloroa c e ta te
So d . mono chlo r o a c e ta te
3 . 4 . 5-T e s t e r
2 .4 .5 -T e s t e r
2 .4 .5 - T e s t e r 2
2.4-D e s t e r
Sod. m onochloroa c e t a t e : 1 w a te r ,
1
-rj^diesel
o2 i l
Sod. mono c h lo r o a c e ta te
So d . mono c h i o ro a c e ta te
2.4-D e s t e r
2 .4 -D e s t e r 2

S

12

12

P

10

2

F

9

9

S
S

1
8
6
10
9

s

5
9
10
10
9
10

s

11

2

F

S
S

F
P

5
5

2

4

10

7
5

9

4

1

F
F
S
S

10
10
10
10

6

2

4
9

9

S

10

F

9

P
S
S

10
10
10

5

1
4

P

s

1

2

5

4
2

3

3

1

3

4

1
1
1

1

1

10

9
2

9 .
8

3
5

3
3

3
1

77
TABLE VI (c o n tin u e d )
T r e a tm ent
d ate
7 /9
7 /9
7 /9
7 /1 5
7 /1 5
7 /1 5
7 /1 5
7 /1 5
7 /1 5
7 /1 5

Group

7 /1 5

IH50-IH59
IH60-IH69
IH70-IH79
IH120-IH129
IH130-Eihl39
IH140-IH149
IH15 0 - IH159
m i6 0 -m i6 9
IH170-IH179
IH 1 8 0 -m i8 9
m i9 o -m i9 6

8 /1 1
8 /1 1

D15-DJ9
DJ10-KT14

8 /1 1

DJ15-DI24

8 /1 1
8 /1 1

KT25-KT34
KT35-KT44

Chemical u s e d
2 .4 .5 - T e s t e r
2 .4 .5 - T ester®
2 .4 . 5 - T e s t e r
2 .4 -D e s t e r
2, 4-D e s t e r
2.4-D ester**
2 .4 .5 - T e s t e r
2 . 4 .5 - T e s t e r
2 . 4 .5 - T e s t e r ~
2 .4 .5 -T e s te r^
2 .4 .5 - T e s t e r , w a te r
s o lu tio n
Sodium a r s e n i t e
Sod. m onochloroac e ta te ^
Sod. m onochloroa c e ta te
2 .4 .5 -T e s te r
2.4-D e s t e r

^ Number o f t r e e s
Me uh- -----------------------° d T1 D ND I H

s
s

F
3

F
S

s

F
S

s

p
F
3?

F
S
S

10 7 2 1
10 10
3
10 7
2 6 2
10
10
1 4 5
2
6 1
1
10
2
1
10 7
10 4 4 2
10 5 2 3
10 10
7
5

5

7

2
3
10 10
5 6 1
10
10 1 2 4 3
5

I t means t o t a l , D means dead, ND means n e a r l y dead,
I means showing i n j u r y , and H means h e a l t h y .
^Double s t r e n g t h (16# a . h . g .) .
^ T r i p l e s t r e n g t h (24# a . h . g .) .
^ F r i l l e d and t r e a t e d on one s id e o f t r e e o n ly .

78
I n g e n e r a l i t can be s a i d t h a t t h e
c o u ld be p e e l e d e a s i l y ,

o n ly t r e e s which

a t t h e tim e o f ex a m in a tio n , were

th o s e which had been f r i l l e d and t r e a t e d w ith sodium monoc h l o r o a c e t a t e , and were

l i s t e d as dead.

■which had b een t r e a t e d a s l a t e

Even th o s e t r e e s

as A ugust 11 were i n a p e e l -

a b le c o n d i t i o n .
T rees t r e a t e d w ith 2 ,4 ,5 - T and l i s t e d a s dead were
showing s i g n s o f b ark l o o s e n i n g , e s p e c i a l l y i n t h e v i c i n i t y
o f t h e s p ra y e d a r e a s .

The t r e e s k i l l e d w ith 2,4-D were

f a i r l y r e s i s t a n t to p e e li n g , a s were th o se -which had been
t r e a t e d by means o f sodium mono ch lo ro a c e t a t e a p p l i e d to a
p e e le d g i r d l e .
A check made i n O c to b e r, 1952, i n d i c a t e d t h a t i n a d d i­
t i o n to t h e f r i l l e d t r e e s , t r e a t e d w ith sodium m onochloroa c e t a t e , m ost o f t h o s e t r e a t e d w ith 2 ,4 ,5 - T i n Ju ne, and now
dead, a p p e a re d to be i n a s a t i s f a c t o r y p e e li n g c o n d i t i o n .
T able V II i s a summary o f a n o th e r i n s p e c t i o n , made on
t h e same t r e e s , on Ju n e 13, 1955.

P r a c t i c a l l y every t r e e

l i s t e d a s dead i n t h i s summary was i n good p e e l i n g condi­
tio n .

The b ark o f many t r e e s was s p l i t t i n g from t h e ground

to t h e to p o f t h e tr u n k .

T his was e s p e c i a l l y t r u e o f th o s e

t r e e s t r e a t e d w ith sodium mono c h lo ro a c e t a t e , a lth o u g h n o t
c o n f in e d e x c l u s i v e l y to them ( s e e F ig u r e s 9 and 1 0 ) .

T rees

l i s t e d as showing i n j u r y o r n e a r l y dead p e e le d ab o u t t h e
same a s u n t r e a t e d t r e e s i n some c a s e s ; i n o t h e r s th e y were
d e f i n i t e l y h a r d e r to p e e l .

79
TABLE V II
SUMMARY OF INSPECTION MADE ON JUNE 13, 1953,
OF ASPEN TREATED DURING 1952
(S means b a s a l s p ra y , P means p e e le d g i r d l e ,
and F means f r i l l g i r d l e * )
T re a t­
ment
d ate

Group

6 /4
6 /2 4

D1-D15
IK1-IK10

6/24

IK ll-rK 2 0

6 /2 4

IK21-IEC25

6/24
6 /24
6 /2 4
6 /2 4
6 /2 5
6/25

L&26-IK55
IK36-IK45
DK46-IK55
E&56-IK64
DK65-IK74
UC75-IK85

6 /2 5
6/2 5

7/3
7/3
7/3
7/3
7/3
7/3
7/9
7/9
7/9
7/9
7/9

JK86-IK90
EK91-IK95
1X95-1X104
XK10 5- DK114
3X115-1X124
1X125-3X134
3X135-3X144
1X145-3X153
Uil-IHIO
BELLI-3X19
EH20-3X29
3X30-1X39
3X40-3X49

Chemical u s e d

Number o f t r e e s
Meth­
od T3- D ND I H

2 ,4 ,5 - T e s t e r
S
Sod* m onochloroa c e ta te
P
Sod. m onochloroa c e ta te
F
So d . mo no chlo r o a c e ta te
S
2 ,4 ,5 -T e s te r
S
p
2 , 4 ,5 - T e s t e r
2 ,4 ,5 - T e s t e r 3
S
2 ,4 -D e s t e r
S
P en t a ehlo ro ph eno 1
s
-jP
e
n
ta
c
h
lo
ro
p
h
e
n
o
l
>
2
g 2 ,4 , 5 - T e s t e r
s
None
F
F
None
Sod. monociiloroa c e ta te
P
Sod. m onochloroa c e ta te
F
F
2 ,4 ,5 -T e s te r
2 ,4 ,5 - T e s t e r
S
2 ,4 ,5 - T e s t e r 3
s
2 ,4 -D e s t e r
s
Sod. m onochloroa c e t a t e : 1 w a te r,
d ie se l o il
s
Sod. mono c h lo r o a c e ta te
F
Sod. m onochloroa c e ta te
P
2 ,4 -D e s t e r
s
2,4-D e s t e r 3
s

122 12

9

3

9

9

4
9
9

1

10

10

9

9

1

1

2

3

7

2
2

2

3

1

4

1
1

2

1

9
9

10

11

5

4

5

4
3

1 1 1

9

7

10
10
10

8
10

6

6

10

2

9

9

10

9

10
10

6

9

9

2
2

1

9

9

1

80
TABLE V II ( c o n tin u e d )
T re a t­
ment
d a te

Group

7 /9
7 /9
7/9
7/1 5
7/1 5
7 /1 5
7 /1 5
7 /1 5
7/1 5
7 /1 5
7 /1 5

DH50-IH59
EH60-IH69
IH70-LH79
IE 1 2 0 - m i2 9
EH130-IH159
IH140-IH149
IH150-IH159
IH160-IH169
DE170-LH179
IH180-IH189
IH190-IH196

8 /1 1
8/11

DJ5-DJ9
DJ10-DJ14

8 /1 1

DI15-DJ24

8 /1 1
8 /1 1

DI25-DJ34
DI35-DJ44

Chemical u s e d

Numb e r o f t r e e s
Meth­
od rp! D ND I H

2 ,4 ,5 -T e s te r
2 ,4 ,5 - T e s t e r 3
2 ,4 ,5 - T e s t e r
2,4 -D e s t e r
2,4 -D e s t e r
2 ,4 -D e s t e r ^
2 ,4 ,5 - T e s t e r
2 ,4 ,5 - T e s t e r
2 ,4 ,5 - T e s t e r 3
2 ,4 ,5 - T e s t e r ^
2 , 4 , 5 - T e s t e r , w a te r
so lu tio n
Sodium a r s e n i t e
Sod. m onochloroa c e ta te 5
Sod. m onochloroa c e ta te
2 ,4 ,5 - T e s t e r
2,4-D e s t e r

9
10
9
2

1

S
s
F
S
F
S
S
F
S
S

10
10
9
10
10
10
10
10
10

4
8
10
8
10

F
F

7
5

5

F

5

2

1

2

F
S

10
10
10

10
5
5

3
3

2
1

s

10

1
2

4
1

3
5
3

Double s t r e n g t h (16# a . h . g .) .

^ T r i p l e s t r e n g t h (24#

a .M l.

g .)

5F r i l l on one s i d e o f t r e e o n ly .

2

2
2

7

-*-T means t o t a l , D means dead, ND means n e a r l y dead,
I means showing i n j u r y , and H means h e a lth y *
o
T o ta l number o f t r e e s may n o t a g re e w ith th o s e g iv en
i n T able VI, b ec au se some t r e e s were f e l l e d f o r exam ination
and o t h e r s were down due to n a t u r a l c a u se s .
rz

2
1

1

81
From T a b le s VI and V II i t can be seen t h a t sodium mo­
no c h lo ro a c e t a t e a p p l i e d i n f r i l l s , and 2 ,4 ,5 - T e s t e r a p p l i e d
a s a b a s a l s p ra y a p p e a re d to b e t h e m ost e f f e c t i v e t r e a t ­
m en ts t r i e d i n t h i s s tu d y .
The i n f l u e n c e o f tim e o f t r e a tm e n t on t h e e f f e c t i v e ­
n e s s o f c h e m ic a ls and m e th o d s .

T ab les VI and V II show t h a t

sodium mono c h lo ro a c e t a t e a p p a r e n tl y was as e f f e c t i v e when
a p p l i e d l a t e i n t h e summer a s i t was when a p p lie d e a r l i e r .
On t h e o t h e r hand , 2,4-D and 2 ,4 ,5 -T a p p e a re d to be much
l e s s e f f e c t i v e when a p p l i e d i n August th a n when a p p l i e d i n
Ju n e,
A d d itio n a l i n f o r m a tio n co n c ern in g tim e o f t r e a tm e n t
was o b t a in e d from o b s e r v a t i o n s made on t r e e s t r e a t e d a t th e
J e n n is o n f o r e s t d u rin g t h e s p r i n g o f 1953.

An ex am in atio n

o f t h e s e t r e e s on F e b ru a ry 18, 1954, showed t h a t , w ith one
e x c e p tio n , a l l o f them w ere dead, and t h a t t h e b ark co u ld
e a s i l y be s t r i p p e d from t h e i r t r u n k s .

These t r e e s h a d a l l

been t r e a t e d i n l a t e A p r i l and e a r l y May and ap p eared to
have re sp o n d e d to t r e a tm e n t a s w e ll a s th o s e -which had been
t r e a t e d d u rin g Ju n e and J u l y .

In fo rm a tio n p e r t a i n i n g to

ch e m ic a ls and ty p e o f t r e a tm e n t u se d on t h e s e t r e e s can be
o b ta in e d from T able I I .
M is c e lla n e o u s o b s e r v a t i o n s .

I t was o b se rv e d t h a t

t r e e s which had been f r i l l e d and t r e a t e d w ith sodium monoc h l o r o a c e t a t e on one s i d e o n ly d id n o t dev elop t h e c h a ra c -

82
t e r i s t i c b la c k b a rk a s q u ic k ly a s t h o s e which h a d been
f r i l l e d and t r e a t e d aro u n d t h e e n t i r e c ir c u m f e r e n c e .
Twenty-two days a f t e r t r e a t i n g , t h e b ark im m e d ia te ly above
t h e f r i l l e d a r e a was t u r n i n g a d ark o ra n g e c o l o r , w h ile t h e
b ark on t h e u n t r e a t e d s i d e o f t h e t r e e rem ained g re e n .

By

c u t t i n g away t h e o u t e r p o r t i o n o f t h e b ark i t was o b se rv e d
t h a t t h e phloem and eam b ial r e g io n s im m e d ia tely above t h e
f r i l l e d p o r t i o n o f t h e b ark were t u r n i n g a brow nish c o lo r ,
w h ile t h e t i s s u e above t h e u n t r e a t e d p o r t i o n o f t h e stem, ap­
p e a re d to be norm al ( s e e F ig u r e 1 1 ) .

However, th e crowns

a p p e a re d to be dying u n ifo rm ly on a l l s i d e s o f t h e s e t r e e s .
Upon re -e x a m in in g t h e s e t r e e s i n June o f 1953, i t was found
t h a t two were dead and t h r e e were s t i l l p ro d u c in g a few g re e n
l e a v e s ; t h e b ark on t h e t r e a t e d s i d e o f t h e stems was s p l i t ­
t i n g and was b la c k e n e d b u t ap p e ared to be h e a l t h y on t h e u n ­
t r e a t e d s i d e s o f a l l b u t one t r e e .
During t h e summers o f 1952 and 1955, i t was n o te d t h a t
i n t h e m a j o r i t y o f c a s e s damage to t h e stem bark was f i r s t
seen on t h e s o u th e a s t s i d e o f t h e t r e e .

I n t h e ca se o f

t r e e s t r e a t e d w ith sodium mono ch lo ro a c e t a t e , t h e b ark ap­
p e a re d to t u r n b la c k m ore q u i c k l y .

The d i s c o l o r e d s p o t s and

e x u d a tio n s o f r e s i n o u s f l u i d , c h a r a c t e r i s t i c o f t r e e s t r e a t ­
ed w ith 2 , 4 , 5 - T and 2 ,4 -D , were a l s o n o te d f i r s t on t h e
s o u th e a s t s i d e o f t h e t r e e s .

The d e a th o f l e a v e s , however,

was o b s e rv e d to o c c u r s im u lta n e o u s ly th ro u g h o u t t h e crowns o f
th e t r e e s .

83
Of t h e 361 t r e e s t r e a t e d d u rin g 1952, e v id e n c e o f a t ­
t r a c t i o n to " w ild life was o n ly found i n one g ro u p .

T h is

group had been t r e a t e d w ith a b a s a l sp ra y c o n s i s t i n g o f a
m i x t u r e o f sodium m o n o c h lo ro a c e ta te i n w a t e r and d i e s e l o i l .
The group c o n s i s t e d o f 10 t r e e s and ev ery t r e e showed s ig n s
of w ild life a c tiv ity .

The moss from around t h e b ase o f each

t r e e had been e a te n , e x p o sin g t h e r o o t c o l l a r ,

in a d d itio n ,

numerous h o l e s had been dug between, and u n d e r, t h e r o o t s o f
th e t r e e s .

(See F ig u r e 1 2 .)

Hie d ep th o f f r i l l s appeared to h ave a p ronounced e f ­
f e c t on t h e s u c c e s s o f t h i s ty p e o f t r e a t m e n t .
t h a t deep f r i l l s ,

I t was n o te d

c u t t i n g i n t o t h e sapwood f o r a t l e a s t o n e-

h a l f in c h , were much more e f f e c t i v e th a n s h a llo w f r i l l s
■vdiieh b a r e l y sc o re d t h e sapwood.

T r e e s w ith deep f r i l l s

were n o t o n ly k i l l e d more q u ic k ly b u t could be p e e le d c le a n ­
e r and a t an e a r l i e r d a t e .

I t was a ls o e s t a b l i s h e d t h a t

t r e e s w ith deep f r i l l s resp onded to tr e a tm e n t more r e a d i l y
th a n t r e e s w hich had r e c e i v e d a p e e le d g i r d l e p r i o r to
sp ra y in g .
R e g a r d le s s o f t h e ty p e o f t r e a tm e n t u se d , i t was n o te d
t h a t t h e s i z e o f t h e t r e e s a p p e ared to i n f l u e n c e t h e e f f e c ­
tiv e n e ss o f tre a tm e n ts.

Even when a d d i t i o n a l s o l u t i o n was

a p p l i e d i n an e f f o r t to com pensate f o r s i z e , t h e b e s t r e ­
s u l t s were o b t a i n e d on t r e e s w hich ran g ed from 5 to 9 in c h e s
in d ia m e te r a t b r e a s t h e i g h t .

Many t r e e s above 10 in c h e s i n

84
d ia m e te r w ere fo u n d to be h e a l t h y and v ig o ro u s one y e a r a f t ­
e r t r e a t i n g ; o t h e r s , a lth o u g h dead, d id n o t p e e l as s a t i s ­
f a c t o r i l y as th e sm aller t r e e s .
I n m ost c a s e s , i t was found t h a t t r e a t e d t r e e s p e e le d
b e t t e r t h e s p r i n g o r summer fo llo w in g t r e a tm e n t th a n th e y
d id t h e autumn f o llo w in g t r e a t m e n t .

One o b j e c t i o n to t h i s

p ro c e d u re was t h e d i s c o l o r a t i o n t h a t develo p ed , in t h e o u t e r
in c h o f sapwood, as t h e t r e e s sto o d o v e r w i n t e r .

T h is d i s ­

c o l o r a t i o n n e c e s s i t a t e d a d d i t i o n a l b le a c h in g f o r c e r t a i n
ty p es o f p ap er p ro d u c ts.

D is c o lo re d sapwood seemed to be

more p r e v a l e n t i n t h e t r e e s t r e a t e d w ith sodium m onochloroa c e t a t e th a n w ith t r e e s t r e a t e d w ith t h e o t h e r c h e m ic a ls .
I t was p r e s e n t to some d e g re e , however, i n m ost c h e m ic a lly
t r e a t e d t r e e s which had sto o d o v e r t h e w i n t e r .
I t was a ls o found t h a t t h e b a rk o f pulpwood s t i c k s
which came from t h e u p p e r p o r t i o n s o f t h e t r e e u s u a l l y were
more d i f f i c u l t to p e e l th a n t h o s e which came from t h e low er
p o rtio n s.

T h is was more n o t i c e a b l e i n t r e e s t r e a t e d w ith

2 ,4 , 5 - T and 2 ,4 -D th a n w ith t h o s e t r e a t e d w ith sodium monoc h lo ro a c e ta te .

T h is c o n d i t i o n h e ld t r u e one y e a r a f t e r

t r e a t i n g as w e ll a s d u rin g t h e same y e a r .
I t was n o te d t h a t t h e bark o f some t r e e s , t r e a t e d w ith
sodium m o n o c h lo r o a c e ta te , c o u ld n o t be p e e le d o f f i n l a r g e
s h e e ts b u t b rok e up i n t o v e ry sm all p i e c e s .

T h is b ark ap­

p e a re d to be i n an advanced s ta g e o f d i s i n t e g r a t i o n and i n

85
many c a s e s lo n g f i b r o u s s t r a n d s o f b a rk a d h e re d to t h e t r e e
tra n k .

86

Fig* 5 .

A spen t r e e , t r e a t e d w i t h 2 , 4 , 5-T e s t e r , show ing
c o m p le te d e f o l i a t i o n 45 d a y s a f t e r tr e a tm e n t*

Fig-v* 6 * Stem o f a s p e n t r e a t e d w i t h 2 , 4 , 5 - T e s t e r showing
r i n g s o f b la c k e n e d xylem t i s s u e r e s u l t i n g from t r e a t m e n t

88
F i g . 7 . Stem o f a sp e n t r e a t e d w i t h B,4-D e s t e r , showing
e x u d a tio n o f r e s i n o u s f l u i d from d i s c o l o r e d s p o ts .

F i g . 8 . B ranch o f a s p e n t r e e t r e a t e d w ith 3 , 4 , 5 - T e s t e r ,
show ing t y p i c a l v a r i e g a t e d c o l o r fo u n d 80 d a y s
a f t e r tre a tm e n t.

90
F ig . 9 .

F ig . 10.

B ase o f t r e e t r e a t e d w i t h 2 , 4 , 5 - T e s t e r ,
s p l i t t i n g and d i s c o l o r a t i o n o f b a r k
on e y e a r a f t e r t r e a t m e n t .

show ing

U pper p o r t i o n o f a s p e n t r e e t r e a t e d w i t h 2 , 4 , 5-T
e s t e r , showing s p l i t t i n g o f s t o n b a rk
one y e a r a f t e r t r e a t i n g .

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F i g . 1 1 . Aspen t r e e t r e a t e d w i t h sodium m o n o c h l o r o a c e t a t e ,
showing d i s c o l o r a t i o n o f phloem above t r e a t e d h a l f o f
stem , and show ing h e a l t h y t i s s u e above u n t r e a t e d
h a l f o f stem .

F i g . 1 2 . Base o f t r e e t r e a t e d w i t h sodium mono c h l o r o a c e t a t e ,
showing e v id e n c e o f w i l d l i f e a c t i v i t y . Moss h a s b e e n e a te n
from r o o t c o l l a r and num erous h o l e s w ere dug
under ro o ts.

VI.

LABORATORY DATA ON THE ANATOMY OF STEMS? TWIGS,
LEAVES, AND ROOTS—WITH APPLICABLE
FIELD OBSERVATIONS

A# Stem Anatomy o f U n tr e a te d T re e s
1 . D e s c r ip tio n o f t h e Cambial Region and A d ja c e n t T is s u e s o f
t h e Stem
T h is d e s c r i p t i o n i s baded on sam ples ta k e n from stems
a t a p p ro x im a te ly 5 f e e t above t h e ground, and c o l l e c t e d a t
v a r io u s tim e s d u rin g t h e growing s e a s o n .
Cambial r e g i o n .

The cam bial r e g io n , i n c l u d i n g u n d i f ­

f e r e n t i a t e d xylem and phloem c e l l s , v a r i e s from 5 to 15
c e l l s i n w id th , depending on t h e tim e o f se a so n .

The amount

and n a t u r e o f th e c e l l c o n te n ts a ls o v a r i e s d u rin g t h e grow­
in g se a so n , ra n g in g from abundant to s c a r c e , and from a
g r a n u la r to a f l u i d s t a t e .
ffilem .

The xylem o f aspen stem s is composed o f v e s s e l s ,

f i b e r s , l o n g i t u d i n a l parenchyma, and ra y parenchym a.
wood i s t y p i c a l l y d i f f u s e p o ro u s , w i t h

The

v e s s e l s o f approx­

im a te ly t h e same d ia m e te r th ro u g h o u t t h e grow th r i n g s .

Ves­

s e l s a r e i n m u l t i p l e s o f two o r m ore, equipped w ith sim ple
p e rfo ra tio n

p la te s.

L o n g itu d in a l parenchyma i s m o s tly t e r ­

m in a l, form ing a broken l i n e a t th e e x tre m ity o f each growth

95
rin g .

Rays a r e u n i s e r i a t e and f o l l o w a r a t h e r s t r a i g h t

c o u rse th ro u g h t h e x ylem .

F i b e r s a r e r e l a t i v e l y numerous,

e s p e c ia lly in th e o u te r p o rtio n o f th e rin g s ; w alls a re r e l ­
a tiv e ly th in .
Phloem .

Phloem was found to c o n s i s t o f l o n g i t u d i n a l

parenchyma, r a y parenchym a, s i e v e t u b e s , companion c e l l s ,
f i b e r s , and some s c l e r e i d s .

As seen i n F ig u r e 113, s ie v e

t u b e s a r e much l a r g e r and have t h i c k e r w a l l s th a n t h e s u r ­
ro und ing c e l l s ; s ie v e p l a t e s , p r i n c i p a l l y on t h e r a d i a l
w a l l s , a r e p l a i n l y v i s i b l e b ecause o f t h e i r t h i c k ap p e a ra n c e ,
which i s due to d e p o s i t i o n s o f c a l l o s e .

E xtruded n u c l e o l i

a r e a c o n s t a n t f e a t u r e o f t h e s i e v e tu b e s d u rin g t h e growing
sea so n ; one can be se e n a t t h e extrem e r i g h t s i d e o f F i g ­
u r e 13.

I t was n o te d t h a t t h e s ie v e tu b e elem ents p o s s e s s

lo n g , s lo p in g end w a l l s , c o n t a in in g compound s i e v e p l a t e s .
Each s ie v e p l a t e c o n t a i n s from 8 to 12 s i e v e a r e a s .

F ig ­

u r e 14 shows t h e compound s i e v e p l a t e s and e x tru d e d n u c l e o l i
o f th e sie v e tu b e s .

L o n g i t u d in a l parenchyma c e l l s a r e

s m a lle r i n d ia m e te r and have t h i n n e r w a lls th a n t h e s ie v e
tu b e s ; companion c e l l s a r e t h e s m a l l e s t in d ia m e te r, occupy­
in g t h e c o r n e r s o f t h e s ie v e t u b e s .

S ie v e t u b e s , companion

c e l l s , and l o n g i t u d i n a l parenchyma c e l l s form b road ta n g e n ­
t i a l bands o f t i s s u e which a l t e r n a t e w ith n a rro w e r, tan g en ­
t i a l bands o f f i b e r s .

C ry s ta llife ro u s c e lls are fre q u e n tly

found i n t h e v i c i n i t y o f t h e f i b e r s (s e e F ig . 1 5 ) .

S c le r-

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e id s a r e o c c a s i o n a l l y found a d ja c e n t t o t h e cam bial re g io n ;
f a r t h e r o u t th e y a r e q u i t e numerous and i n t e r s p e r s e d among
th e f ib e r s .
2. C o n d itio n o f t h e Cambial Region and Adjacen.t T i s s u e s o f
th e Stem a t D i f f e r e n t

Times o f t h e

Year

a . C o n d itio n on F e b ru a ry

18 (s e e F ig .

16)

Cambial r e g i o n .

C ell w a l l s w ere f ir m and r e l a t i v e l y

t h i c k ; c e l l s were r e c t a n g u l a r in sh ap e, a l i g n e d i n o r d e r l y
r a d i a l rows, and were i n

a c o n tr a c t e d

s t a t e . Thee n t i r e r e ­

gion was a p p ro x im a te ly 5 c e l l s w ide. C ell c o n t e n t s

were

v ery a b u n d a n t, r a t h e r g r a n u l a r , and s t a i n e d q u i t e dark w ith
sa fra n in .
Xylem.

A d i s t i n c t d i v i d in g l i n e c o u ld be seen between

th e cam bial re g io n and m a tu re xylem c e l l s .

V e s s e ls and f i ­

b e r s , form ed t h e p r e v io u s y e a r , were a l l f u l l y developed and
possessed r e l a t i v e l y th ic k w a lls .

Ray parenchyma, a d j a c e n t

to th e cam bial r e g io n , had c e l l c o n te n ts s i m i l a r to t h o s e o f
th e cam bial r e g io n .
Phloem.

The l a s t formed c e l l s o f th e p r e v io u s y e a r

were s t i l l u n d i f f e r e n t i a t e d .

They were a p p ro x im a te ly th e

same s i z e i n d ia m e te r and p o s s e s s e d c o n te n ts s i m i l a r to
th o s e a l r e a d y d e s c r i b e d .

E x te rn a l to t h e s e c e l l s , t h e d i f ­

f e r e n t i a t e d e le m e n ts c o u ld be s e e n .

S ieve t u b e s appeared to

be l a c k i n g i n cytoplasm ; s ie v e p l a t e s were devoid o f e a l l o s e , and no e x tru d e d n u c l e o l i co u ld be d e t e c t e d .

Companion

97
c e l l s and l o n g i t u d i n a l parenchym a c e l l s were r i c h i n c e l l
c o n te n ts,
h . C o n d itio n on A p r i l 24 (s e e F i g , 15)
F ie ld ;.o b s e rv a tio n s ♦

Buds were g re e n and expanded b u t

n o t open,
Cambial r e g i o n .

C e l l s were no l o n g e r i n o r d e r l y rows;

w a l l s were n o t a s firm o r t h i c k as r e p o r t e d f o r F e b ru a ry .
C e ll c o n t e n t s w ere changing from a g r a n u l a r to a more o r
l e s s f l u i d s t a t e ; th e y were n o t as dense and d id n o t t a k e up
s t a i n as r e a d i l y a s th o s e r e p o r t e d f o r F e b ru a ry .
X ylan.
Phloem .

No change n o t e d .
C e lls r e p o r t e d as bein g u n d i f f e r e n t i a t e d in

F eb ru ary now were found to be d i f f e r e n t i a t i n g i n to t h e v a r i ­
ous ty p e s o f s p e c i a l i z e d t i s s u e s .

C e ll c o n te n ts th ro u g h o u t

th e phloem were d i s p e r s i n g and ap p ro ach in g a f l u i d s t a t e ,
c. C o n d itio n on May 29 ( s e e F i g . 17)
F ie ld o b s e rv a tio n s .

Leaves o f t h e sample t r e e s were

f u l l y d ev elo p ed .
Cambial r e g i o n .

Cambium was a c t i v e l y d i v i d i n g , form ing

new xylem and phloem c e l l s .

Cambial c e l l s were w id e r i n a

r a d i a l d i r e c t i o n th a n p r e v i o u s l y n o te d .
was much w id e r th a n r e p o r t e d b e f o r e .

The cam bial r e g io n

I t was n o t p o s s i b l e to

d i s t i n g u i s h w ith c e r t a i n t y between cam bial re g io n and a d j a ­
c e n t t i s s u e s b ec au se o f many u n d i f f e r e n t i a t e d c e l l s .

C ell

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c o n t e n t s were now i n a f l u i d s t a t e and e v i d e n t l y had l o s t
much o f t h e i r c h r o m a t i c i t y .
Xylem.

F i r s t formed v e s s e l s and f i b e r s a l r e a d y had

secon dary w a l l s ; th o s e which had j u s t d i f f e r e n t i a t e d p o s­
s e s s e d t h i n p rim a ry w a l l s .
ra p id r a t e .

Xylem c e l l s were fo rm in g a t a

C e ll c o n t e n t s were abundant i n newly formed r a y

c e lls but scarce in o th e rs .
Phloem.

S ie v e tu b e s had e n la rg e d and now were t h r e e to

f o u r tim e s a s l a r g e i n d ia m e te r as t h e su rro u n d in g c e l l s o f
l o n g i t u d i n a l parenchyma; t h e w a l l s a ls o were t h i c k e r th a n
t h o s e o f t h e parenchym a c e l l s .

S iev e p l a t e s were a c q u ir in g

a d e p o s it o f c a l l o s e and a s a r e s u l t were v e ry p ro m in e n t.
E xtruded n u c l e o l i were a p p e a rin g i n t h e m a tu re s ie v e tu b e s ,
and cytoplasm was found l i n i n g t h e w a l l s ,
d. C o n d itio n on J u l y 30 ( see F ig . 13)
Cambial r e g i o n .

The cam bial re g io n was much n arro w er

th a n on May 29; c e l l s were more n e a r l y i n rows and were ap­
p ro a c h in g a r e c t a n g u l a r sh ap e.

C e ll c o n te n ts were approach­

in g a g r a n u l a r s t a t e a g a in , and t h e e n t i r e r e g io n had an ap­
p e a ra n c e o f d e c re a s e d a c t i v i t y .
Xylem.

Most xylem c e l l s were f u l l y d i f f e r e n t i a t e d .

Very few t h i n - w a l l e d v e s s e l s o r f i b e r s could be d e te c te d ,
and e v i d e n t l y v e r y few new c e l l s were b e in g formed.
Phloem .

Phloem c e l l s were s t i l l forming v e r y slow ly;

s ie v e tu b e s a d j a c e n t to t h e cambial r e g io n had n o t expanded

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to t h e i r f u l l s i z e .

C a llo s e and e x tru d e d n u c l e o l i co u ld

s t i l l he d e t e c t e d i n t h e m a tu re s ie v e t u b e s ,
e. C o n d itio n on August 20 {see F ig . 18)
Cambial r e g i o n .

Appearance o f c e l l s was about t h e same

as r e p o r te d on J u l y 30, e x c e p t t h a t c e l l c o n te n ts seemed to
be more g r a n u l a r .
Xylem.
Phloem .

No change n o te d .
Some s i e v e p l a t e s were t h i c k e r th a n r e p o r t e d

on J u ly 50, e v i d e n t l y a s a r e s u l t o f i n c r e a s e d c a l l o s e de­
p o sits.

A d i s t i n c t a b se n ce o f e x tru d e d n u c l e o l i was a ls o

n o te d i n m ost s ie v e t u b e s .

The c o n t e n ts o f many phloem

/

c e l l s were q u i t e g r a n u l a r , and became d a r k ly s t a i n e d w i t h /
sa fra n in .

B. P r o g r e s s i v e E f f e c t s o f Chem icals on t h e Stem Anatomy
o f T re e s T re a te d D uring 1952
1 . E f f e c t s o f Sodium M o n o c h lo ro a c e ta te on th e Cambial Region
and A d jacent T is s u e s
U nless o t h e r w is e s t a t e d , a l l sam ples w ere ta k e n a t ap­
p ro x im a te ly 5 f e e t above t h e ground from t h e ston. o f t r e e
IK-17.

T h is t r e e was f r i l l e d and sp ray e d on June 24, and

samples removed p e r i o d i c a l l y d u rin g t h e summer (s e e T able
III) .
a . F i f t e e n days a f t e r t r e a t i n g ( s e e F i g . 19)
F ie ld o b s e rv a tio n s .

A ll l e a v e s were t u r n i n g brown and

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w ith e r e d i n a p p e a ra n c e ; stem b ark i n t h e v i c i n i t y o f t h e
f r i l l was a ls o t u r n i n g brown.
Qambial r e g i o n .

The w a lls o f m ost c e l l s were d i s t o r t e d

and i n a s t a t e o f p a r t i a l c o l l a p s e ; i n some p l a c e s i t was
alm ost i m p o s s ib le to d i s t i n g u i s h i n d i v i d u a l c e l l s .

C o n ten ts

and w a lls o f a l l c e l l s were s t a i n e d a dark brown due to
chem ical t r e a t m e n t , and i n s p o t s th e y were fu s e d t o g e t h e r .
Xylem.

Some c e l l s im m ed iately a d j a c e n t to t h e cam bial

r e g io n were becoming d i s t o r t e d .

Ray c e l l s a d j a c e n t to t h e

cam bial re g io n c o n ta in e d dark c o n t e n t s , s i m i l a r to t h o s e o f
t h e cambium.
Phloem .

I t was n o te d t h a t m ost s ie v e tu b e s were p a r ­

t i a l l y c o l l a p s e d ; w a l l s were much t h i c k e r th a n th o s e o f n o r ­
mal t u b e s and were s t a i n e d a dark brown c o l o r .

I n some

c a se s i t was v e ry d i f f i c u l t to l o c a t e s ie v e p l a t e s b ecau se
th e y resem bled t h e w a l l s o f o t h e r c e l l s i n t h i c k n e s s and
c o lo ra tio n .
c a llo se .

When v i s i b l e th e y had v e ry heavy d e p o s i t i o n s o f

F ig u r e 20, a t h ig h m a g n i f i c a t i o n , shows s ie v e

tu b e s w ith p l a t e s .

I t was a ls o n o te d t h a t m ost s i e v e tu b e s

were devoid o f e x tru d e d n u c l e o l i .

The w a l l s o f many l o n g i ­

t u d i n a l parenchyma c e l l s were becoming t h i c k - w a l l e d ; th e y
were d i s t o r t e d and i n an e a r l y s ta g e o f c o l l a p s e .
sue was v e r y much d i s t o r t e d .

Ray t i s ­

In some a r e a s i t was ex tre m e ly

d i f f i c u l t to t r a c e t h e p a t h o f a ra y th ro u g h t h e cambium i n ­
to t h e phloem .

C e ll c o n te n t s o f t h e r a y s were s t a i n e d dark

101

brown and were f u s e d w ith t h e w a l l s n e a r t h e cam bial r e g i o n .
The o n ly ele m e n ts i n t h e phloem t h a t did n o t seem to be a f ­
f e c t e d by t h e t r e a tm e n t were t h e bands o f f i b e r s and s c l e r eid s.

The a p p e a ra n c e o f t h e phloem can be compared w ith

t h a t o f u n t r e a t e d phloem c o l l e c t e d a t t h e same tim e by com­
p a r in g F ig u re s 19 and E l.
b. T w en ty -th ree days a f t e r t r e a t i n g
F ie ld o b se rv a tio n s .

Tree was co m p le te ly d e f o l i a t e d .

Bark from f r i l l to abo ut 5 f e e t above t h e f r i l l was com­
p l e t e l y b lack e n ed ; from 5 f e e t above f r i l l to to p o f t r e e ,
and from f r i l l to a b o u t 18 in c h e s below, th e b a rk had an
orange-brow n c o l o r .
Cambial r e g i o n .

The amount o f c o l l a p s e , and t h e degree

o f d i s i n t e g r a t i o n o f th e w a lls was more advanced th a n a t 15
days.

The dark brown c o l o r o f c e l l c o n t e n t s was more p r o ­

nounced and t h e c o n te n ts were d i s i n t e g r a t i n g in some c e l l s .
Xylem.

Many newly formed c e l l s were b e g in n in g to show

s i g n s o f c o l l a p s e and g e n e ra l d i s t o r t i o n .

Ray c e l l s were

becoming d i s t o r t e d and i n an e a r l y s t a t e o f c o l l a p s e a d j a ­
c e n t to th e cam bial r e g io n .
Phloem .

Very few s ie v e tu b e s co u ld be d i s t i n g u i s h e d .

S iev e p l a t e s were h a r d to d e t e c t i n t h o s e s ie v e tu b e s which
could be seen .

Ray c e l l s a d ja c e n t to t h e cambium were s t a r t ­

in g to d i s i n t e g r a t e and had b la c k e n e d w a l l s and c o n t e n t s .
No damage to f i b e r s o r s c l e r e i d s c o u ld be d e te c te d .

102

c. T h ir ty days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

T ree had a p p ro x im a te ly t h e same

ap p e aran c e a s d e s c r i b e d a t 23 days; b lack e n ed b a rk a r e a s ex­
te n d e d about 2 f e e t f u r t h e r up t h e t r u n k .
Oambial r e g i o n .

I t was im p o s s ib le to d i s t i n g u i s h i n ­

d i v i d u a l c e l l s i n t h e cambium.

C o lla p s e had become se v e re

and g e n e ra l th ro u g h o u t th e e n t i r e r e g io n .

C e ll c o n te n ts

c o u ld n o t be d i s t i n g u i s h e d from t h e w a lls ; b o th ap peared as
b l a c k i s h m asses o f m a t e r i a l , a p p a r e n tly Jo in e d t o g e t h e r .

In

many p l a c e s , r a y s l o s t a l l c o n t i n u i t y th ro u g h th e cambium.
Xylem.

Not much change in ap p earan ce o f t h e xylort

could be d e t e c t e d .

The degree o f d i s i n t e g r a t i o n o f ra y

c e l l s was g r e a t e r th a n a t 23 days.
Phloem .

Almost a l l c e l l w a l l s , except th o s e o f f i b e r s

and s c l e r e i d s were i n an advanced s t a t e o f c o l l a p s e and d i s ­
in te g ra tio n .

C e lls c l o s e to t h e cam bial re g io n were more

d i s t o r t e d th a n th o s e f a r t h e r o u t .

The lumens o f many c e l l s

were s m a lle r i n d ia m e te r th an th o s e o f u n t r e a t e d m a t e r i a l
becau se o f th e t h i c k w a l l s .

B lackened c e l l c o n t e n t s were

g e n e r a l th ro u g h o u t t h e phloem.

Even l o n g i t u d i n a l parenchyma

in th e o u t e r r e g io n s c o n ta in e d dark c o n t e n t s .

I n many a r e a s

t h e c o n t i n u i t y betw een gro u p s o f f i b r o u s c e l l s and a d ja c e n t
parenchym atous t i s s u e was b ro k e n , le a v in g i s o l a t e d groups o f
f i b e r s and s c l e r e i d s .

103

d. T h i r t y - s i x days a f t e r t r e a t i n g ( s e e F i g . 22)
F ie ld o b s e rv a tio n s .

Stem b ark was b la c k e n e d from t h e

f r i l l to t h e to p o f t h e t r e e w ith o n ly a few narrow , g re en
s t r e a k s re m a in in g .
Cambial r e g i o n .
Xylem.
Phloern..
day s.

No change n o te d .

No change n o te d .
C e ll w a l l s were more d i s t o r t e d th a n a t 30

In many p l a c e s , a d j a c e n t to t h e cam bial re g io n , th e

phloem was i n t h e form o f t a n g e n t i a l bands o f b la c k m a t e r i a l .
C e ll c o l l a p s e was com plete and no i n d i v i d u a l c e l l shapes
co uld be d e te rm in e d .

Rays ap p e ared as s o l i d b la c k l i n e s

t w i s t i n g th ro u g h t h e phloem.

F i b e r s and s c l e r e i d s s t i l l

seemed to be i n t a c t , b u t t h e sp ac es between g roup s o f f i b e r s
and s c l e r e i d s , and a d ja c e n t parenchym atous m a t e r i a l were
much more pronounced th a n a t 30 days.
e . F o r t y - f i v e days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .
a t 30 day s.

A ppearance o f t r e e was t h e same as

I t was n o te d , however, t h a t t h e b ark im m ediate­

l y above t h e f r i l l e d a r e a c o u ld be s t r i p p e d o f f by hand.
Cambial r e g i o n .

The cambium had th e a p p e aran c e o f a

d is o r g a n iz e d t a n g e n t i a l band o f b lack e n ed t i s s u e .

R a d ia l

w a lls were s e v e r e l y c o l l a p s e d and I t was im p o s s ib le to d is ­
tin g u is h in d iv id u a l c e lls .
Xylem.

Most c e l l s im m e d ia tely a d ja c e n t to t h e cam bial

zone were i n an i n t e r m e d i a t e s t a g e o f d i s i n t e g r a t i o n ,

in

104
some a r e a s d i s t i n c t s e p a r a t i o n s c o u ld be seen betw een cam­
b i a l zone and xylem .
Phloem .

The o n ly i n t a c t c e l l s i n t h e phloem were bands

o f f i b e r s and s c l e r e i d s .

A ll o t h e r c e l l s were u n d e rg o in g a

p ro c e s s o f d i s i n t e g r a t i o n .
f . F i f t y - o n e , 57, and 64 days a f t e r t r e a t i n g
F ie ld o b se rv a tio n s.
p e a ra n c e o f t h e t r e e .
above t h e f r i l l ;
to p o f t h e t r u n k .

Not much change was n o te d i n ap­

The b ark was alm ost co m p le te ly b la c k

o n ly a few g re en p a tc h e s rem ained n e a r t h e
Bark c o u ld be s t r i p p e d o f f more e a s i l y as

tim e went on; a t 64 days i t was d i f f i c u l t to remove stem
samples w ith o u t s e p a r a t i n g bark from wood.
Cambial r e g io n , xylem, and phloem .
little

There was v e ry

change i n a p p e a ra n c e d u rin g t h i s p e r i o d .

A ll c e l l s ,

e x c e p t f i b e r s and s c l e r e i d s , were d i s i n t e g r a t i n g v e ry slow­
ly .
g. S even ty -o n e days a f t e r t r e a t i n g (s e e F ig u re s 23 and 24)
F ie ld o b s e rv a tio n s .

Tree was co m p le te ly dead above

f r i l l ; no g re e n b ark was v i s i b l e .

Bark was a ls o c o m p le te ly

b lack e n ed from f r i l l to a p o i n t about one f o o t below f r i l l .
Below t h i s p o i n t t h e r e s t i l l were numerous g reen b ark
p a tc h e s .

The b ark above t h e f r i l l was v e ry l o o s e and ex­

trem e c a r e had to be u s e d In o r d e r to remove sam ples i n an
undamaged c o n d i ti o n .

105

Cambial r e g i o n .
la p s e d .

Cambial r e g io n had c o m p le te ly c o l ­

I t was i m p o s s ib le to d e te rm in e where t h e cam bial

r e g io n ended and phloem o r xylem began.

A ll t r a c e s o f c e l l

c a v i t i e s had been o b l i t e r a t e d , and t h e e n t i r e r e g io n ap­
p e a r e d as a c o a l - b l a c k mass o f d i s t o r t e d t i s s u e .
Xylem.

The l a s t - f o r m e d c e l l s o f t h e xylem were i n an

advanced s t a t e o f d i s i n t e g r a t i o n , l e a v i n g many sm all la c u n a e
betw een xylem and cam bial r e g i o n .

Some ra y c e l l s a d ja c e n t

to t h e cambial zone had d i s i n t e g r a t e d ; o t h e r s had b la c k e n e d
w a l l s and c o n t e n t s .
Phloem .

The s i e v e tu b e s , companion c e l l s ,

and p a re n ­

chyma c e l l s a d j a c e n t t o t h e cam bial re g io n had c o m p le te ly
c o l l a p s e d , form ing a wide t a n g e n t i a l band o f t w i s t e d , b la c k ­
ened w a ll m a t e r i a l .

F a r t h e r o u t c o l l a p s e was n o t so p r o ­

nounced, b u t t h e w a l l s were v e ry t h i c k and had t h e same
b la c k e n e d ap p e a ra n c e a s th o s e a d j a c e n t to t h e cam bial r e ­
g io n .

Rays c o u ld n o t be d i s t i n g u i s h e d c l o s e to t h e cam bial

r e g io n and f a r t h e r o u t th e y were c o m p le te ly dead, c o n t a i n i n g
b la c k e n e d c e l l c o n t e n t s .
24.

T h is c o n d i t i o n can be se e n i n F ig .

I n many p l a c e s t h e r e were numerous v o id a r e a s between

bands o f i n t a c t f i b r o u s c e l l s and a d j a c e n t parenchym atous
m a te ria l.

T h is c o n d i t i o n was g e n e r a l th ro u g h o u t t h e p h lo o n ,

even i n t h e o u t e r p o r t i o n s o f t h i s r e g io n (s e e F i g . 2 3 ).

106

2. E f f e c t s o f 2 ,4 ,5 - T E s t e r on t h e Cambial Region and Ad­
j a c e n t T is s u e s
U n le s s o th erv d .se s t a t e d , a l l sam ples w ere ta k e n a t ap­
p r o x im a te ly 5 f e e t above t h e ground from t h e stem o f t r e e
IK -27.

T his t r e e was t r e a t e d by t h e b a s a l s p ra y m ethod on

Ju n e 24 and sam ples removed p e r i o d i c a l l y d u rin g t h e summer
(see T able I I I ) .
a . F i f t e e n days a f t e r t r e a t i n g (s e e F i g . 25)
F ie ld o b s e rv a tio n s .
v ig o ro u s a t t h i s tim e .

T re e ap p eared to be h e a l t h y and
A ll f o l i a g e and b a rk a r e a s w ere

g re e n .
Cambial r e g i o n .
Xylem.
P hloem .

No damage c o u ld be d e t e c t e d .

No damage c o u ld be d e t e c t e d .
Many c e l l s p o s s e s s e d v e ry t h i c k w a l l s .

A l­

though no e v id e n c e o f c o l l a p s e co u ld be d e t e c t e d i n m o st
c e l l s o f l o n g i t u d i n a l parenchym a, i t d id ap p e ar i n some
siev e tu b e s .

O th e r s i e v e tu b e s had v e ry sm all c e l l c a v i t i e s

b e c a u s e o f t h e i r e x tre m e ly t h i c k w a l l s .

No e x tru d e d n u c l e o l i

were seen and i t was v e r y d i f f i c u l t to d e t e c t s i e v e p l a t e s .
C e ll c o n te n ts were g r a n u l a r and s t a i n e d q u i t e d ark a s a r e ­
s u lt of tre a tin g .
sc le re id s.

No damage c o u ld be seen i n t h e f i b e r s o r

107
b. T w e n ty -th re e day s a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

L eav es w ere b e g in n in g to t u r n from

g re e n to v a r i o u s sh ad e s o f re d and y e llo w .

Stem b ark was

g re e n ex cep t f o r some sm all d i s c o l o r e d s p o t s on t h e lo w e r 5
o r 6 f e e t o f th e tru n k .

Samples ta k e n a t t h i s tim e were

from t h e c e n t e r o f a s m a ll d i s c o l o r e d s p o t, l o c a t e d ab o u t 2
f e e t above t h e g ro u n d .
Cambial r e g i o n .

Cambial c e l l s were s l i g h t l y d i s t o r t e d

and a few seemed to be i n an e a r l y s t a t e o f c o l l a p s e .
Xylem.
Phloem .

No damage c o u ld be d e t e c t e d .
The phloem was about th e same a s a t 15 d a y s .

C ell c o n t e n t s were a l i t t l e

dark er.

c . T h i r t y days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

A pp roxim ately o n e - h a l f o f t h e

l e a v e s had t u r n e d brown; t h e o t h e r s were c o lo r e d re d and
y e llo w .

The lo w e r p o r t i o n o f t h e t r u n k ap p e ared to be dying

i n l o c a l i z e d s p o ts ; t h e u p p e r p o r t i o n d id n o t seem to be
damaged.

Sample was ta k e n from a h e i g h t o f 2 f e e t , from an

a r e a o f g re e n b a r k .
Cambial r e g i o n .

Cambial r e g io n was ab out t h e same a s

r e p o r t e d f o r 25 days.
Xylem.
P hloem .

No damage c o u ld be d e t e c t e d .
The phloem was i n a b o u t t h e same c o n d itio n as

r e p o r t e d a t 25 d a y s .

108
d. T h i r t y - s i x days a f t e r t r e a t i n g ( s e e F i g u r e s 26 and 27)
F ie ld o b s e rv a tio n s .
a s a t 50 d a y s .

T ree a p p e a ra n c e was ahout t h e same

More l e a v e s had tu r n e d "brown h u t t h e c o n d i­

t i o n o f t h e t r u n k had h o t changed a p p r e c i a b l y .
Camhial r e g i o n .

C e ll w a l l s , e s p e c i a l l y r a d i a l w a l l s ,

w ere s t a r t i n g to c o l l a p s e and p r e s e n t e d a d i s t o r t e d a p p e a r­
ance.

C e ll c o n t e n t s c o u ld n o t he seen.
Xylem.

I n some p l a c e s , new ly formed c e l l s were c o l ­

l a p s i n g and w a l l s w ere d i s i n t e g r a t i n g ,

c a u s in g numerous

sm a ll la c u n a e betw een t h e cam hial r e g io n and xylem .
Phloem .

E x tru d e d n u c l e o l i and s i e v e p l a t e s were n o t

v i s i b l e In t h e s i e v e t u b e s .

Thick t a n g e n t i a l bands o f c o l ­

l a p s e d w a ll m a t e r i a l c o u ld be seen a t v a r io u s p l a c e s In t h e
phloem .

I n o t h e r r e g i o n s , c e l l w a l l s w ere t h i c k and v e r y

d ark b u t had n o t c o l l a p s e d .

U n c o lla p s e d c e l l s were rounded

o r o v a l, re se m b lin g expanded l o n g i t u d i n a l parenchyma c e l l s .
T h is c o n d i t i o n can be seen i n F ig u r e 27.
e . F o r t y - f i v e days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

A ll l e a v e s were c o m p le te ly dead;

t r e e was p a r t i a l l y d e f o l i a t e d .

D is c o lo re d a r e a s i n b ark

w ere l a r g e r , and b la c k r i n g s o f t i s s u e were d is c o v e r e d i n t h e
wood b e n e a th t h e s e a r e a s .
Cambial r e g i o n .
to d i s i n t e g r a t e .
56 d a y s .

C ell w a l l s were b la c k e n e d and s t a r t e d

C o lla p s e was more g e n e r a l th a n r e p o r t e d a t

109
Xylem.

C o lla p s e o f new ly form ed c e l l s was m ore ad­

vanced th a n a t 36 d a y s.

Lacunae were "becoming l a r g e r and

more numerous "between cam bial r e g io n and xylem .

Many r a y s

had b la c k e n e d c e l l c o n t e n t s , i n m ost c a s e s e x te n d in g o u t to
t h e end o f th e grow th r i n g .
P h lo em .

Not much change from 36 days e x c e p t t h a t ex­

t r u d e d n u c l e o l i were v e ry numerous i n t h e s ie v e t u b e s , imme­
d i a t e l y a d j a c e n t to t h e cambium.

F a r t h e r o u t , t h e phloem

had t h e same a p p e a ra n c e a s d e s c r ib e d a t 36 d a y s ^
f . F i f t y - o n e days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

D is c o lo re d s p o t s i n t h e b a rk o f

t h e tr u n k w ere much l a r g e r th a n r e p o r t e d p r e v i o u s l y .

Many

s p o ts had c o a le s c e d , fo rm in g l a r g e a r e a s o f o r a n g e - c o l o r e d
bark.

Many o f t h e d i s c o l o r e d a r e a s were exuding a r e s i n o u s

liq u id .

The sam ple was t a k e n a t 5 f e e t from an a r e a o f

g re e n b ark im m e d ia tely a d j a c e n t to a d i s c o l o r e d s p o t .
Cambial r e g i o n .

The cam bial r e g io n was i n a p p ro x im a te ­

l y th e same c o n d i t i o n a s r e p o r t e d a t 30 d a y s .

The c e l l s

were j u s t s t a r t i n g to show c o l l a p s e , and a few w a l l s w ere
d i s p l a y in g t h e f i r s t s i g n s o f d i s i n t e g r a t i o n .

C e ll c o n t e n t s

were b re a k in g i n t o f r a g m e n ts .
Xylem.
P hloem .

No damage c o u ld be d e t e c t e d .
S ie v e tu b e s w ere i n an e a r l y s t a t e o f c o l ­

l a p s e ; t h o s e a d j a c e n t to t h e cam bial r e g io n w ere n o te d to
have t h i c k w a l l s .

W alls w ere l i n e d w ith d a r k - s t a i n e d c y to ­

110

p la s m .

I t was o b s e rv e d t h a t t h e o u t e r p o r t i o n o f t h e phloem

was much l e s s a f f e c t e d t h a n t h a t c l o s e r to t h e cam hial r e ­
g io n ,

Some s i e v e p l a t e s c o u ld s t i l l he d e t e c t e d , a s w e ll a s

e x tru d e d n u c l e o l i ,
g . F i f t y - s e v e n days a f t e r t r e a t i n g ( s e e F ig u r e s 28 and 29)
F ie ld o b s e rv a tio n s .

D is c o lo re d h a rk a r e a s now extended

from t h e sp ra y e d a r e a to t h e to p o f t h e t r e e .

Sample ta k e n

a t 5 f e e t from d i s c o l o r e d a r e a .
Camhial r e g i o n .
c o lla p se .

C e l l s w ere i n an advanced s t a t e o f

W alls w ere d i s t o r t e d and d i s i n t e g r a t i n g , m aking

i d e n t i f i c a t i o n o f i n d i v i d u a l c e l l s im p o s s ib l e .
t e n t s were g r a n u l a r and b la c k e n e d i n a p p e a ra n c e .

C e ll con­
Many were

d i s i n t e g r a t i n g i n t o f r a g m e n ts .
Xylem.

W alls and c o n te n ts o f Io n g i t u d i n a l and ra y

parenchym a c e l l s w ere s t a i n e d c o a l b la c k .
vanced s t a t e o f d i s i n t e g r a t i o n .

Hays were i n ad­

W alls o f many c e l l s a d j a ­

c e n t to t h e ca m b ial r e g io n were c o l l a p s e d and t o m .

The i n ­

t e r v e s s e l p i t s i n many s p o t s were v e r y b la c k and w ere ob­
s e rv e d to be b u lg in g i n t o t h e v e s s e l c a v i t i e s .

There a ls o

was a p re p o n d e ra n c e o f v e s s e l s and v e ry few f i b e r s a d j a c e n t
to t h e cam bial r e g io n .
P hloem .

A ll c e l l s a d j a c e n t to t h e cam bial r e g io n were

found i n an advanced s t a t e o f c o l l a p s e and d i s i n t e g r a t i o n .
F a r t h e r o u t , c e l l s w ith t h i c k w a l l s were n o te d and v ery
little

c o l l a p s e was o b s e rv e d .

Rays were norm al ex c ep t im-

Ill
m e d i a t e l y a d j a c e n t to t h e cam h ial r e g io n w here th e y had d i s ­
in te g ra te d .

A few e x tru d e d n u c l e o l i were i n e v id e n c e and

o c c a s i o n a l l y a s i e v e p l a t e c o u ld h e d e t e c t e d .
h . S i x t y - f o u r days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .
d isc o lo re d .

L a rg e a r e a s o f t h e t r u n k w ere now

The s p ra y e d a r e a was t u r n i n g an o ra n g e-b ro w n .

The sam ple was t a k e n from t h e s p ra y e d a r e a , a b o u t 2 f e e t
from t h e g round .
Cambial r e g i o n .

C e l l s w ere c o m p le te ly c o l l a p s e d .

It

was im p o s s ib le to d i s t i n g u i s h i n d i v i d u a l c e l l s b ec au se t h e
e n t i r e re g io n a p p e a re d a s a s o l i d , t a n g e n t i a l band o f b l a c k ­
ened, d i s t o r t e d m a t e r i a l .
Xylem.
n o te d .

Some d i s i n t e g r a t i o n o f n e w ly - fo m e d c e l l s was

However, t h e d e g re e o f d i s t o r t i o n and b la c k e n in g was

n o t as g r e a t a s r e p o r t e d a t 57 day s.
m o st.

Hay c e l l s w ere damaged

Many o f them d i s p l a y e d b la c k e n e d w a l l s and c o n t e n t s .
Phloem .

Numerous t a n g e n t i a l bands o f b la c k e n e d m a t e r i ­

a l were n o te d th r o u g h o u t t h e phloem .
as s o l i d b la c k m asses o f m a t e r i a l .

C e ll c o n t e n t s a p p e ared
W alls o f t h e m a j o r i t y o f

c e l l s , even t h o s e t h a t had n o t c o l l a p s e d , w ere v e ry d a r k .
Hay c e l l s a p p e a re d a s s o l i d m asses o f b la c k t i s s u e ; no d i s ­
t i n c t i o n co u ld be made betw een c o n t e n t s and w a l l s .

Many

l a r g e v o id s p a c e s w ere n o te d betw een i n t a c t f i b e r s and
s c l e r e i d s , and a d j a c e n t m a t e r i a l .

112

i* S e v e n ty -o n e days a f t e r t r e a t i n g ( s e e F i g . 30)
F ie ld o b se rv a tio n s.

Trunk above sp ray ed a r e a was a l ­

m ost s o l i d o ra n g e , w i t h l i t t l e g re e n b ark v i s i b l e .
sp ra y e d a r e a was a lm o s t a s o l i d brown.

The

The b a rk o f t h e

s p ra y e d a r e a was i n

a p e e l a b l e c o n d i t i o n , b u t above t h i s

a r e a i t was t i g h t .

Sample was ta k e n

Cambial r e g i o n .

from 5 f e e t .

The cam b ial r e g io n had t h e same ap­

p e a r a n c e as r e p o r t e d a t 64 d a y s .
Xylem.

Many n ew ly-form ed c e l l s had c o l l a p s e d , form ing

numerous sm all l a c u n a e between cam b ial r e g io n and x y la n .

It

was n o te d t h a t some r a y and l o n g i t u d i n a l parenchyma c e l l s
had dark w a l l s and d ark c e l l c o n t e n t s .

However, t h e d e g re e

o f damage to t h e xylem was much l e s s th a n a t e i t h e r 64 o r 57
d a y s.

T his can b e o b s e rv e d by comparing F i g u r e s 28 and 30.
P hlo em .

G-eneral a p p e a ra n c e o f t h e phloem was a b o u t t h e

same a s a t 57 days;

many s ie v e t u b e s

l a p s e d and m ost d e l l s had v e r y

th ic k

were p a r t i a l l y c o l­
w a lls.

T a n g e n tia l

bands o f b la c k e n e d m a t e r i a l were i n e v id e n c e th ro u g h o u t th e
phloem .

F i b e r s and s c l e r e i d s were i n t a c t .

3. E f f e c t s o f 2,4 -D E s t e r on t h e Cambial Region and A d ja c e n t
T is s u e s
U n le s s o t h e r w i s e s t a t e d , a l l sam ples w ere ta k e n a t ap­
p r o x im a te ly 5 f e e t above t h e ground from t h e sto n o f t r e e
IK -6 1 .

T h is t r e e was t r e a t e d by t h e b a s a l s p ra y method on

113
Ju n e 24 and sam ples removed p e r i o d i c a l l y d u rin g t h e summer
( s e e T able

I I I ) .

a . F i f t e e n days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

No e v id e n c e o f damage c o u ld be de­

te c te d .
Cambial r e g i o n .
Xylem.
P h loem .

No damage c o u ld be d e t e c t e d ;

No damage c o u ld be d e t e c t e d .
No damage co u ld be d e t e c t e d .

b . T w e n ty -th re e days a f t e r t r e a t i n g
F ie ld o b se rv a tio n s.

No e v id e n c e o f damage c o u ld be de­

te c te d .
Cambial r e g i o n .
Xylem.
Phloem .

No damage c o u ld be d e t e c t e d ,

No damage c o u ld be d e t e c t e d .
No damage n o te d ex c ep t t h a t t h e c e l l c o n t e n t s

o f many l o n g i t u d i n a l parenchyma c e l l s were s t a i n e d dark
brown, and w ere d i s i n t e g r a t i n g and moving tow ard t h e c e l l
w a l l s , g iv in g t h e w a l l s a t h i c k a p p e a ra n c e .
c. T h i r t y - s i x days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

The l e a v e s were s t a r t i n g t o t u r n

v a r i o u s shad es o f r e d and y e llo w .

A few d i s c o l o r e d s p o ts

were foun d on t h e lo w e r 10 f e e t o f t h e tru n k ; a r e s i n o u s
f l u i d was o b se rv e d on some o f t h e s p o t s .

Sample was ta k e n

from a d i s c o l o r e d s p o t .
Cambial r e g i o n .

No damage c o u ld be d e t e c t e d .

114
Xylem.
P h lo em .
befo re.

No damage c o u ld be d e t e c t e d .
C e ll c o n t e n t s had a d a r k e r c o l o r t h a n n o te d

The w a l l s o f m ost parenchym atous c e l l s ,

e sp e c ia lly

s i e v e tu b e s and l o n g i t u d i n a l parenchyma, w ere becoming v e r y
t h i c k ; no e v id e n c e o f c o l l a p s e was d e t e c t e d .
d. F o r t y - f i v e days a f t e r t r e a t i n g
F ie ld o b s e rv a tio n s .

Not much change i n a p p e a ra n c e ;

some l e a v e s s t i l l g re e n ; d i s c o l o r e d s p o t s on tru n k m ore nu­
m erou s.
Cambial r e g i o n .
X y lan .
P hloem .

No damage c o u ld be d e t e c t e d .

No damage c o u ld be d e t e c t e d .
C e ll c o n t e n t s were v e ry dark and fra g m e n ta ry ;

m ost o f them were l i n i n g t h e w a l l s .
e. F i f t y - o n e days a f t e r t r e a t i n g (s e e F i g . 31)
F ie ld o b s e rv a tio n s .

A ll l e a v e s had changed c o l o r .

Many d i s c o l o r e d s p o t s had developed on t h e lo w e r h a l f o f t h e
tr u n k ; u p p e r p o r t i o n was s t i l l e n t i r e l y g re e n .

Much f l u i d

was b e in g exuded by d i s c o l o r e d s p o t s .
Cambial r e g i o n .

Very l i t t l e

c o l l a p s e o r d i s t o r t i o n was

found a t t h i s tim e ; c e l l w a l l s w ere d a r k e r th a n t h o s e o f un­
t r e a t e d m a t e r i a l and th e y w ere m ore r i g i d .

Cambial r e g io n

was devoid o f c e l l c o n te n ts a s compared w ith u n t r e a t e d ma­
t e r i a l (compare F i g u r e s 31 and 3 2 ).
Xylem.

No damage co u ld be d e t e c t e d .

115
Phlo em .

C e ll c o n t e n t s and w a l l s o f m o st paren chym atous

c e l l s w ere s t a i n e d b l a c k ; w a l l s o f m ost w ere v e ry t h i c k .
Ray c e l l s were v e ry much d i s t o r t e d .

L o n g it u d in a l parenchym a

and s i e v e tu b e s d id n o t show much c o l l a p s e , a lth o u g h s i e v e
p l a t e s and e x tru d e d n u c l e o l i were v e r y d i f f i c u l t to d e t e c t .
f . F i f t y - s e v e n days a f t e r t r e a t i n g
F ie ld o b se rv a tio n s.

Most l e a v e s had tu r n e d brown; d i s ­

c o lo r e d s p o t s w ere s p re a d in g to u p p e r p o r t i o n s o f t h e t r u n k .
Cambial r e g i o n .

C e ll w a l l s were v e r y t h i c k , d i s t o r t e d ,

and were s t a r t i n g to c o l l a p s e .
Xylem.

C o n te n ts o f ra y c e l l s c l o s e s t to t h e cambium

s t a r t e d to d a rk e n .
Phloem .

C o n d itio n abou t t h e same a s a t 51 d a y s.

g . S i x t y - f o u r days a f t e r t r e a t i n g
F ie ld o b se rv a tio n s.

A ppearance o f t r e e ab o u t t h e same

a s a t 57 d a y s.
Cambial r e g i o n .

C o lla p s e o f c e l l s was becoming v e ry

g e n e r a l th ro u g h o u t t h e e n t i r e cam bial r e g io n .
Xylem.
phloem .

No change from 57 days.
No change from 57 d a y s.

h . S e v e n ty -o n e days a f t e r t r e a t i n g ( s e e F ig u re s 33 and 34)
F ie ld o b s e rv a tio n s .

A ll l e a v e s w ere brown b u t v e ry

l i t t l e d e f o l i a t i o n had ta k e n p l a c e .

Sprayed a r e a o f tr u n k

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had t u r n e d brown; above sp ray e d p o r t i o n l a r g e a r e a s o f o r ­
ange b a rk were fo rm in g .
Cambium.
la p se ;

E n t i r e r e g io n was i n a s t a t e o f s e v e r e c o l ­

c e l l w a l l s w ere b la c k and d i s t o r t e d , fo rm in g a t a n ­

g e n t i a l band o f d i s i n t e g r a t e d m a t e r i a l .
Xylem.

A few c e l l s im m e d ia te ly a d j a c e n t to t h e cam b ial

r e g io n w ere o b s e rv e d to be c o l l a p s i n g .

E xcept f o r t h e s e

c e l l s , t h e xylem was i n t a c t .
Phloem .

G eneral c o l l a p s e and d i s t o r t i o n was n o te d ad­

j a c e n t to t h e cam bial r e g i o n .

F a r t h e r o u t , m ost c e l l s ,

ex­

c e p t f i b e r s and s c l e r e i d s , had ab no rm ally t h i c k w a lls and
many were i n a s t a t e o f p a r t i a l c o l l a p s e .

T h is c o n d itio n

gave th e a p p e a ra n c e o f v e r y sm all c e l l c a v i t i e s (compare
F ig u r e s 34 and 35) .

S ie v e p l a t e s and e x tru d e d n u c l e o l i

co u ld n o t be d e t e c t e d .
aged.

F i b e r s and s c l e r e i d s were n o t dam­

The phloem was v e r y s i m i l a r i n a p p e a ra n c e to t h e

phloem o f 2 ,4 , 5 - T t r e a t e d m a t e r i a l .

T h is c o n d itio n can be

seen by comparing F i g u r e s 30 and 33.

C. Appearance o f t h e Cambial Region and A d ja c e n t Stem
T is s u e s R e s u l t i n g from Chemical T re a tm e n ts
A p p lie d on D i f f e r e n t D ates
T re e s u se d f o r t h i s s tu d y were t r e a t e d on d i f f e r e n t
d a te s d u rin g t h e growing s e a s o n .

A ll sam ples were o b t a i n e d

117
56 days a f t e r t r e a t i n g , and w ere removed' from t h e stem a t
a p p ro x im a te ly 5 f e e t above t h e ground ( s e e T ab le IV ).
1. The Appearance o f Stem T is s u e s Taken from T re e s T re a te d
on D i f f e r e n t D ates w ith Sodium Mo no c h lo ro a c e t a t e in
F rills
a . . Tree t r e a t e d on Ju n e 24 ( s e e F i g . 22)
F ie ld o b s e rv a tio n s .

Tree was c o m p le te ly d e f o l i a t e d .

Stem b a rk was b la c k from t h e f r i l l to t h e to p o f t h e t r e e
w ith o n ly a few n a rro w g re e n s t r e a k s re m a in in g .
Cambial r e g i o n .

I t was Im p o s s ib le to d i s t i n g u i s h i n ­

d i v i d u a l c e l l s i n t h e cambium.
v e re ly c o lla p se d .

The e n t i r e r e g io n was s e ­

C e ll c o n t e n t s and w a lls were s t a i n e d

b la c k and seemed to be fu s e d t o g e t h e r .

I n many p l a c e s t h e

p a t h o f r a y s c o u ld n o t be fo llo w e d .
Xylem.

Many new ly-form ed c e l l s were b e g in n in g to show

s ig n s o f c o l l a p s e .

Ray c e l l s a d ja c e n t to t h e cam bial r e g io n

were d i s t o r t e d and i n an e a r l y s t a t e o f c o l l a p s e .
Fhloesm.

C o lla p s e and d i s i n t e g r a t i o n was g e n e r a l

th ro u g h o u t t h e e n t i r e r e g i o n .

F i b e r s and s c l e r e i d s o f t e n

appeared a s i s o l a t e d g ro u p s becau se o f t h e d i s i n t e g r a t i o n
and c o l l a p s e o f p arenchym atous c e l l s around them.

I t was

ex tre m e ly d i f f i c u l t to i d e n t i f y d i f f e r e n t t y p e s o f p a r e n ­
chymatous c e l l s i n some p l a c e s .

Rays a p p e a re d as s o l i d

b la c k l i n e s t w i s t i n g th ro u g h t h e phloem.

Where s ie v e tu b e s

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could "be d i s t i n g u i s h e d , i t was d i f f i c u l t to l o c a t e s i e v e
p la te s.

E x tru ded n u c l e o l i were n o t o b se rv e d i n t h e p h lo e n .

b . Tree t r e a t e d on J u l y 5(see F ig . 36)
F ie ld o b s e rv a tio n s .

Tree was p a r t i a l l y d e f o l i a t e d ; a l l

re m a in in g l e a v e s were brown.

Stem b ark was b la c k e n e d f o r

ab o u t 4 f e e t above f r i l l .
Cambial r e g i o n .

C e lls were o b s e rv e d to be i n an e a r l y

s t a g e o f c o l l a p s e ; w a l l s were d i s i n t e g r a t i n g i n some p l a c e s ,
i n o t h e r s th e y w ere t h i c k e n i n g .
Xylem.

A few o f t h e l a s t - f o r m e d c e l l s were i n a s t a t e

o f c o l l a p s e , l e a v i n g s m a ll, i s o l a t e d la c u n a e betw een cam bial
r e g io n and xylem .

Ray c e l l s were d i s i n t e g r a t i n g i n some

p l a c e s a d j a c e n t to t h e cambium.

O th e r ra y c e l l s were ob­

s e rv e d to h ave b la c k e n e d c e l l c o n t e n t s .
Phloem .

Much o f t h e phloem a d ja c e n t to t h e cambium was

i n an advanced s t a g e o f d i s i n t e g r a t i o n .
c e l l s had t h i c k b la c k w a l l s ;

F a r t h e r o u t many

some c o l l a p s e was e v i d e n t and

i n some a r e a s f i b e r s and s c l e r e i d s a p p e ared as i s o l a t e d
g ro u p s .

Ray c e l l s were becoming b la c k e n e d and v e r y much d i s ­

to rte d .
c. Tree t r e a t e d on J u l y 9.
F ie ld o b s e rv a tio n s .

T re e was p a r t i a l l y d e f o l i a t e d ; a l l

re m a in in g l e a v e s had t u r n e d b l a c k .

Trunk was g re e n e x c e p t

119
f o r one b la c k s t r e a k ab out 6 i n c h e s wide w hich ex ten d ed from
t h e f r i l l to t h e to p o f t h e t r e e .
Cambial r e g i o n .

Very l i t t l e damage was n o te d ; some

c e l l s w ere i n an e a r l y s t a t e o f c o l l a p s e , w h ile o t h e r s ap­
p a r e n t l y were n o t damaged.
Xylem.
P h lo o n .

No damage c o u ld be d e t e c t e d .
Very l i t t l e

damage was n o te d i n t h e l o n g i t u ­

d i n a l and ra y parenchym a c e l l s .

Some s ie v e t u b e s a d j a c e n t

to t h e cam bial r e g i o n were In an e a r l y s t a t e o f c o l l a p s e .
Many ap peared to be n orm al, h a v in g n o rm a l-a p p e a rin g s ie v e
p l a t e s b u t no e x tru d e d n u c l e o l i .
in g was o b s e rv e d .

Very l i t t l e w a ll t h i c k e n ­

B la c k e n in g o f w a ll s and c e l l c o n t e n ts was

found i n i s o l a t e d c e l l s ; m ost o f them were n e a r t h e cam bial
re g io n .
2. The A ppearance o f Stem T is s u e s Taken from T rees T re a te d on
D i f f e r e n t D ates w ith a B asal S pray o f 2 ,4 ,5 - T E s t e r
a . Tree t r e a t e d on Ju n e 24 ( s e e F i g . 26)
F ie ld o b s e rv a tio n s .

A pproxim ately one h a l f o f t h e

le a v e s had tu r n e d brown; t h e o t h e r s were c o lo re d r e d and
y e llo w .

The lo w e r p o r t i o n o f th e tr u n k was dying i n l o c a l ­

iz e d s p o t s ; u p p e r r e g i o n o f t h e stem d i d n o t seem to be dam­
aged.
Cambial r e g i o n .
and become d i s t o r t e d .

C e ll w a l l s were s t a r t i n g to c o l l a p s e
C e l l s seemed to b e dev oid o f c o n t e n t s .

120

Xylem.

I n some p l a c e s , n ew ly-form ed c e l l s were c o l ­

l a p s e d and w a l l s w ere d i s i n t e g r a t i n g , c a u sin g num erous sm all
la c u n a e betw een cam bial r e g io n and xylem .
Phloem .

The phloem was c h a r a c t e r i z e d by c o lla p s e d

c e l l s , t h i c k d ark w a l l s , and absence o f e x tru d e d n u c l e o l i
and s ie v e p l a t e s .

Thick t a n g e n t i a l bands o f w a ll m a t e r i a l

cou ld be s e e n a t v a r i o u s p l a c e s i n t h e phloem .

In o th e rs ,

c e l l w a l ls w ere t h i c k and v e ry dark b u t t h e c e l l s had n o t
co llap sed .

Those which had n o t c o l l a p s e d were rounded o r

o v a l.
b . Tree t r e a t e d on J u l y 3
F ie ld o b se rv a tio n s.

A ll l e a v e s tu r n e d brow n, b u t ap­

p a r e n t l y a l l were s t i l l a t t a c h e d .
Cambial r e g i o n .

Some ev id en ce o f w a l l s becoming r i g i d ;

o th e r w is e no damage was o b s e rv e d .
Xylem.

No damage n o te d e x c e p t a few r a y c e l l s had

dark-brow n c o n t e n t s .
Phloem .

Some c o l l a p s e and some w a ll th i c k e n i n g was

n o te d , b u t n o t a s p ro nou nced a s i n t h e t r e e t r e a t e d on June
84.

Many l o n g i t u d i n a l and ra y parenchyma c e l l s had dark

co n te n ts.
c. Tree t r e a t e d on J u l y 9
F ie ld o b se rv a tio n s.

M ost l e a v e s were c o lo re d r e d and

y ello w ; o n ly a few w ere brown.
c o u ld be d e t e c t e d .

No e v id en c e o f stem i n j u r y

121

Cambial r e g i o n .

C e lls were i n a p p ro x im a te ly t h e same

c o n d i t i o n as t h o s e d e s c r ib e d f o r t r e e t r e a t e d on J u l y 9.
Xylem.
Phloem .

No damage c o u ld be d e t e c t e d .
Some c o l l a p s e and w a ll t h i c k e n i n g was n o t e d .

Parenchyma c e l l s had d a r k - c o l o r e d c o n t e n t s .
d. Tree t r e a t e d on J u l y 15 ( s e e P i g . 37)
F ie ld o b s e rv a tio n s .

A ppearance was a b o u t t h e same a s

t h a t o f t r e e t r e a t e d on J u l y 9.
Cambial r e g i o n .
Xylem.

No damage co u ld d e t e c t e d .

Damage c o u ld be d e t e c t e d i n c e l l w a l l s .

The

c o n te n ts o f some r a y and l o n g i t u d i n a l parenchyma c e l l s w ere
s t a i n e d a v e ry dark brown.
Phloem .

Very l i t t l e w a ll d i s t o r t i o n was n o te d , b u t

w a ll t h i c k e n i n g was becoming q u i t e g e n e r a l .
were e x tre m e ly d i f f i c u l t to d e t e c t .

S iev e p l a t e s

C e ll c o n t e n t s i n many

c e l l s were q u i t e g r a n u l a r and i n many c e l l s were s t a i n e d a
deep p u r p l e .
5, The A ppearance o f Stem T is s u e s Taken from T rees T r e a te d
on D i f f e r e n t D ates w ith 2,4 -D E s t e r A p p lie d as a B asal
S pray
a. T ree t r e a t e d on J u n e 24.
F ie ld o b s e rv a tio n s .

L eaves w ere s t a r t i n g to t u r n v a r i ­

ous sh ad e s o f r e d and y e llo w .

A few d i s c o lo r e d s p o ts were

122

found on t h e lo w e r 10 f e e t o f t h e t r u n k .
c o lo re d s p o ts w ere exuding a r e s i n o u s
Cambial r e g i o n .
Xylem.
Phloem .

No damage c o u ld

M ost o f t h e d i s ­

flu id .
be d e t e c t e d .

No damage c o u ld be d e t e c t e d .
C e ll c o n t e n t s w ere v e ry

m ost parenchym atous c e l l s , e s p e c i a l l y

d a rk .

Thw w a l l s o f

s i e v e t u b e s , w ere

b e­

coming v e r y t h i c k ; no e v id e n c e o f c o l l a p s e was d e t e c t e d .
b . Tree t r e a t e d on J u l y 5
F ie ld o b se rv a tio n s.

A few l e a v e s w ere t u r n i n g c o l o r .

Trunk appeared to be undamaged.
Cambial r e g i o n .
Xylem.
Phloem .

No damage c o u ld be d e t e c t e d .

No damage co u ld be d e t e c t e d .
About t h e same as r e p o r t e d f o r t r e e t r e a t e d on

June 24.
c. T ree t r e a t e d on J u l y 9
F ie ld o b s e rv a tio n s .

A few c o lo re d l e a v e s were o b s e rv e d .

No e v id e n c e o f stem damage was fo u n d .
Cambial r e g i o n .
Xylem.
Phloem .

No damage could be d e t e c t e d .

No damage co u ld be d e t e c t e d .
Very l i t t l e damage was o b s e rv e d .

Some e v i ­

dence o f w a ll t h i c k e n i n g was se e n , b u t no c o l l a p s e o r d i s i n ­
t e g r a t i o n could be fo u n d .
d. Tree t r e a t e d on J u l y 15 (s e e F ig . 38)
F ie ld o b se rv a tio n s.

No damage o f anykihd was o b s e rv e d .

123
Cambial r e g i o n , xylem, and phloem..
ty p e was n o t e d .

No damage o f any

A ll c e l l s a p p e a re d to be n o rm al.

T h is can

be seen by com paring F i g u r e s 18 and 38.

E f f e c t s o f 2 , 4 , 5-T E s t e r a t D i f f e r e n t H e ig h ts
i n t h e T ree Stem
Sam plesfbr t h e s e o b s e r v a t i o n s were o b t a i n e d from t r e e
Dl.

T his t r e e was t r e a t e d w ith a b a s a l s p ra y on June 4 and

f e l l e d 80 days a f t e r t r e a t i n g .

Samples were removed from

t h e stem a t v a r i o u s i n t e r v a l s , from t h e sp ra y e d a r e a to t h e
t i p o f th e le a d e r .
At t h e tim e o f f e l l i n g , t h e t r e e was c o m p le te ly d e f o l i ­
a t e d , and t h e b a rk o f t h e stem was c o m p letely d i s c o l o r e d .
The b ark o f t h e s p ra y e d a r e a was a s o l i d brown; above t h e
s p ra y e d a r e a i t was a v a r i e g a t e d o ra n g e and brown.

The b a rk

c o u ld be p e e le d from around t h e sp ray ed a r e a b u t was t i g h t
on t h e rem a in d e r o f t h e s t a n .

B ranches were b la c k e n e d and

b a rk was p e e li n g f o r a d i s t a n c e o f about 18 i n c h e s back to
th e t i p s .

The p o r t i o n from t h e tru n k o u t to t h e t i p was

c o lo re d t h e same as t h e t r u n k .

The t i p o f t h e l e a d e r was

b la c k e n e d t h e same as t h e b ran ch t i p s .
a . O b s e r v a tio n s on a sample ta k e n fiom t h e sp ra y e d a r e a ( s e e
F ig . 39)
Cambial r e g i o n .

C e lls o f t h e cam bial a r e a were i n a

g en eral s t a t e o f c o lla p s e .

The w a l l s a p p e a re d to be i n an

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advanced s t a g e o f d i s i n t e g r a t i o n ; i t was v e ry d i f f i c u l t to
d e te rm in e i n d i v i d u a l c e l l s .
s e rv e d to be v e r y d a rk .

W alls and c o n t e n t s were ob­

Ray c e l l s c o u ld n o t be t r a c e d

th ro u g h t h e cam bial r e g i o n .
Xylem.

The w a l l s o f some c e l l s a d j a c e n t to t h e cam bial

r e g io n had c o l l a p s e d ,

ca u sin g sm all la c u n a e betw een cam bial

zone and xylem .
Phloem .

Many c e l l s , m o s tly s ie v e t u b e s , a d j a c e n t to

t h e cam bial r e g io n were i n a p a r t i a l s t a t e o f c o l l a p s e .
Rays were v e ry d i s t o r t e d n e a r t h e cam bial r e g io n , and w a ll
t h i c k e n i n g o f a l l c e l l s was g e n e r a l .
b. O b s e rv a tio n s on a sample from 5 f e e t above ground (s e e
F ig . 40)
AL1 t i s s u e s a p p e a re d to be t h e same as th o s e o f t h e
sp ray ed a r e a .

T h is can be i l l u s t r a t e d by comparing F ig u r e s

39 and 40.
c. O b s e r v a tio n s on a sam ple from 10 f e e t above t h e ground.
Cambial r e g i o n .
cam bial r e g io n .
Xylem.

Very l i t t l e damage was o b se rv e d i n t h e

Some c o l l a p s e was n o te d i n a few c e l l s .

Most c e l l s ap p e ared undamaged; a sm all number

o f l a s t - f o r m e d c e l l s had c o l l a p s e d w a l l s .
Phloem .

Very l i t t l e

c o l l a p s e was n o te d ; c e l l w a ll

t h ic k e n i n g was g e n e r a l th ro u g h o u t th e phloem.

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d. O b s e r v a tio n s on a
Cambial r e g i o n .

sam ple from 15 f e e t above

t h e grou nd.

Very e a r l y s t a g e s o f c o l l a p s e w ere

n o te d i n a few c e l l s .
Xylem.

No damage c o u ld be d e t e c t e d .

Phloem .

Some w a ll th i c k e n i n g was n o t e d .

Some s i e v e

p l a t e s w ere v i s i b l e , b u t w a l l s c o n ta in in g them were becoming
t h i c k and were i n an

e a rly sta g e o f c o lla p se .

e . O b s e rv a tio n s on a

sample from 20 f e e t above

Cambial r e g i o n .
Xylem.

t h e g ro und .

No damage was d e t e c t e d .

No damage was d e t e c t e d .

Phloem .

Some w a ll t h i c k e n i n g n o te d ; v e ry l i t t l e

l a p s e was s e e n .

c o l­

Some e x tru d e d n u c l e o l i were v i s i b l e and a l ­

so a few s ie v e p l a t e s .
f . O b s e r v a tio n s on a sam ple from 55 f e e t above t h e ground
(s e e F ig . 41)
A ll t i s s u e s were i n about t h e same c o n d i t i o n as r e p o r t ­
ed f o r 20 f e e t .
g. O b s e r v a tio n s on a sample from t h e b la c k e n e d p o r t i o n i n
t h e t i p o f t h e l e a d e r (s e e F ig . 42)
Cambial r e g i o n .

Cambial r e g io n was c o m p le te ly k i l l e d

and ap p eared a s an a lm o st s o l i d , b la c k , t a n g e n t i a l band o f
m a te ria l.

I t was i m p o s s ib l e to d i s t i n g u i s h betw een w a l l s

and c e l l c o n te n t s ; b o th were b la c k and fu s e d t o g e t h e r .

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Xylem.

L a s t- f o r m e d c e l l s were b a d ly d i s t o r t e d i n

s p o ts ; many a p p e a re d to be i n an i n t e r m e d i a t e s t a g e o f c o l ­
la p s e .
Phloem .

C e ll c o n t e n t s and w a l l s w ere b la c k e n e d and

fu s e d t o g e t h e r .

I t was im p o s s ib le to d i s t i n g u i s h d i f f e r e n t

ty p e s o f parenchym atous c e l l s .

The f i b e r s and s c l e r e i d s

were t h e o n ly c e l l s t h a t a p p e ared to be undamaged.

E. M is c e lla n e o u s O b s e rv a tio n s
1 . The E f f e c t s o f Doubling t h e C o n c e n tra tio n o f 2 , 4 ,5 - T
E ste r
These o b s e r v a t i o n s were made on sam ples removed from
th e stem o f t r e e IK -4 9, t r e a t e d by t h e b a s a l s p ra y m ethod on
June 24.

The sam ples were o b t a i n e d on t h e same days as

th o s e f o r t h e t r e e t r e a t e d w ith s i n g l e s t r e n g t h 2 , 4 ,5 - T
(s e e T able I I I ) .

I n f o r m a tio n r e g a r d in g o b s e r v a t i o n s on

s i n g l e s t r e n g t h sam ples can be found i n s e c t i o n VI, B-2.
Even though l e a v e s o f t h e t r e e t r e a t e d w ith double
s t r e n g t h s o l u t i o n had been damaged more q u ic k ly th a n th o s e
o f t h e t r e e t r e a t e d w ith a s i n g l e s t r e n g t h s o l u t i o n , t h e ap­
p e a ra n c e o f t h e t r e e stem s i n t h e f i e l d was q u i t e s i m i l a r .
O b s e r v a tio n s made on t h e anatomy

o f t h e cam bial r e g io n

and a d j a c e n t t i s s u e s f a i l e d to d i s c l o s e any s i g n i f i c a n t d i f ­
f e r e n c e s betw een t h e two c o n c e n t r a t i o n s u s e d .

T h is was t r u e

f o r s l i d e s examined a t each tim e i n t e r v a l a f t e r t r e a t i n g .

A

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com parison betw een F ig u r e s 30 and 43 w i l l show t h a t t h e de­
g re e o f i n j u r y , 71 days a f t e r t r e a t i n g , was a b o u t t h e same
f o r b o th c o n c e n t r a t i o n s .
2. The E f f e c t s o f Chem icals on Twigs
Samples w ere removed from tw ig s when t h e o u te rm o s t 6 to
8 in c h e s were b la c k e n e d .

I n each i n s t a n c e one sam ple was

ta k e n from t h e b la c k e n e d p o r t i o n ; tw ig s were a p p ro x im a te ly
o n e - e i g h th in c h i n d ia m e te r i n t h i s r e g i o n .

A second

sample was a ls o removed a p p ro x im a te ly 2 f e e t below t h e p o i n t
o f l e a f a tta c h m e n t.

Twigs av e rag ed abo ut t h r e e - e i g h t h s o f an

in c h i n d ia m e te r a t t h i s p o i n t .

Twig b ark was n o t b la c k e n e d

i n t h i s a r e a , a lth o u g h i t f r e q u e n t l y was d i s c o l o r e d .
The e f f e c t s o f t h e v a r i o u s chem ical tr e a tm e n ts were
v ery s i m i l a r on tw ig s .

T h e re fo re , o n ly o b s e r v a t i o n s made on

sam ples ta k e n from a tw ig t r e a t e d w ith 2 ,4 ,5 - T have been
d e s c r ib e d .

T h e .o n ly n o t i c e a b l e e f f e c t i n sam ples ta k e n 2

f e e t below l e a f a tta c h m e n t was a s l i g h t t h i c k e n i n g o f some
o f t h e parenchym atous c e l l w a l l s .

I n sam ples removed from

t h e b lack e n ed p o r t i o n o f t h e tw ig s, t h e cambium was d i s t o r t ­
ed and c o lla p s e d ; w a l l s and c e l l c o n t e n t s were c o m p le te ly
b la c k e n e d .

A ll parenchym a c e l l s , in c l u d in g t h o s e o f th e

phloem, xylem, and p i t h had d a r k - c o l o r e d w a l l s and b la c k e n e d
c e ll c o n te n ts.

C e l l s i n t h e phloem were a f f e c t e d more th a n

th o s e o f t h e xylem o r p i t h .

A com parison between u n t r e a t e d

and t r e a t e d tw ig s can be seen i n F i g u r e s 44 and 45.

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3. The E f f e c t s o f Chemical T re atm e n t on L eav es
L ea v es were c o l l e c t e d when t h e y had become b la c k e n e d
and w ere p a r t i a l l y d r i e d o u t .

Samples were removed from

t h a t p o r t i o n o f t h e b la d e c o n t a in i n g t h e m id rib o f t h e l e a f .
The e f f e c t s o f t h e chem ical tr e a tm e n t s were v e r y s i m i l a r , and
o n ly t h e o b s e r v a t i o n s made on a l e a f o f a t r e e t r e a t e d w ith
2,4-D e s t e r have been d e s c r ib e d .
a . D e s c r ip tio n o f p o r t i o n s o f an u n t r e a t e d l e a f ( see F ig u r e s
46 and 47)
M id rib p o r t i o n .

The m id rib p o r t i o n o f t h e l e a f b la d e

c o n ta in s one l a r g e v a s c u l a r b u n d le .
by a bundle s h e a th o f f i b e r s .

The b u n d le i s e n c i r c l e d

This r i n g a p p e a rs to be t h i c k ­

e r In t h e d o r s a l and v e n t r a l p o r t i o n s th a n In t h e s i d e a r e a s ,
as d e s c r ib e d by Eames and M cDaniels ( 9 6 ).

The d o r s a l p o r ­

t i o n o f t h e v a s c u l a r b u n d le c o n ta in s t h e elem en ts o f t h e
phloem, p r i n c i p a l l y s i e v e tu b e s , companion c e l l s and l o n g i ­
t u d i n a l parenchym a.

The v e n t r a l p o r t i o n o f t h e b u n d le i s

composed o f xylem e le m e n ts:
l o n g i t u d i n a l parenchym a.

nam ely, v e s s e l s , f i b e r s , and

Between t h e b u n d le and t h e l e a f

e p id e rm is, u n d i f f e r e n t i a t e d parenchyma c e l l s ,

c ry sta llife r-

ous c e l l s , and a l a y e r o f t h i c k - w a l l e d collenchym a c e l l s
could be s e e n .
B lade p o r t i o n a d j a c e n t to m i d r i b .

The blad_e o f t h e

l e a f , a d j a c e n t to t h e m i d r i b , i s made up o f u p p e r and lo w e r
e p id e r m is , p a l i s a d e c e l l s , and spongy m e s o p h y ll.

The p a l i -

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sade l a y e r i s l o c a t e d i n t h e v e n t r a l p o r t i o n o f t h e "blade
and i s a r ra n g e d i n two h o r i z o n t a l l a y e r s , im m e d ia tely "below
t h e u p p e r e p id e r m is .

These l a y e r s occupy w e ll o v e r t h e u p ­

p e r h a l f o f th e l e a f b la d e .

The spongy m eso p h y ll i s e v id e n t

i n t h e d o r s a l p o r t i o n o f t h e b la d e , and o c c u p ie s a l l t h e
space between t h e p a l i s a d e l a y e r and lo w e r e p id e rm is .

The

spongy m eso phyll a p p e a rs as a l o o s e netw ork w ith numerous
v o id sp aces betw een c e l l s .

At t h e tim e o f c o l l e c t i o n ,

c h l o r o p l a s t s were v e r y numerous and c o u ld be d e t e c t e d i n t h e
c e l l s o f t h e p a l i s a d e l a y e r and spongy m e s o p h y ll.
b. D e s c r ip tio n o f p o r t i o n s o f a t r e a t e d l e a f ( s e e F i g u r e s 48
and 49)
M id rib p o r t i o n .

A ll phloem c e l l s i n th e v a s c u l a r

bu n d le were c o m p le te ly c o l l a p s e d ,
and d r ie d u p .

W alls appeared d i s t o r t e d

C o n ten ts were b la c k e n e d , and i n many c a s e s

could n o t be s e p a r a t e d from w all m a t e r i a l .
i n d i v i d u a l c e l l ty p e s was i m p o s s ib le .

I d e n t i t y o f th e

A ll parenchym atous

t i s s u e i n t h e xylem ap p e a re d to be dead.

C e ll c o n t e n t s and

w a l ls were b la c k and c o u ld n o t always be s e p a r a t e d .
age was d e t e c t e d i n v e s s e l w a l l s .

No dam­

Parenchym atous c e l l s o u t ­

s id e t h e v a s c u l a r b u n d le had b la c k e n e d c e l l c o n t e n t s and
th ic k e n e d w a l l s which w ere p a r t i a l l y c o l l a p s e d .

E piderm al

c e l l s and u n d e r ly in g collenchym a a ls o had dark c e l l c o n t e n t s .
Blade p o r t i o n a d ja c e n t t o m i d r i b .

I t was p r a c t i c a l l y

im p o s s ib le to i d e n t i f y i n d i v i d u a l c e l l s ex c ep t i n t h e e p i-

130

dermal l a y e r s .
to g e th e r.
c o n d i t io n .

W alls and c o n t e n t s were b la c k e n e d and f u s e d

No c h l o r o p l a s t s c o u ld be d e t e c te d b e c a u s e o f t h i s
The e n t i r e b la d e p o r t i o n seemed to have con­

t r a c t e d , r e s u l t i n g i n a much t h i n n e r c r o s s s e c t i o n t h a n t h a t
of u n tre a te d m a te ria l.
4 . The E f f e c t s o f Chemical T re atm e n ts on t h e Main Hoots
Samples f o r t h i s s tu d y w ere o b t a i n e d from t r e e Dl.
T his was t h e same t r e e t h a t was u s e d f o r th e stem stu d y de­
s c r i b e d u n d er s e c t i o n VI-D.

I t was t r e a t e d w ith a b a s a l

s p ra y o f 2 ,4 ,5 - T on Ju n e 4 and sam ples were c o l l e c t e d 80
days a f t e r t r e a t i n g .

At t h e tim e o f sample c o l l e c t i o n t h e

t r e e was c o m p le te ly d e f o l i a t e d , t h e stem b ark above t h e
sp ray ed a r e a was e n t i r e l y d i s c o l o r e d , and t h e bark o f t h e
sp ray ed a r e a , down to t h e r o o t c o l l a r , was b la c k e n e d and
could be p e e le d o f f .
Samples were a ls o c o l l e c t e d from t r e e HCL7.

T h is t r e e

was t r e a t e d w ith sodium m o n o c h lo ro a c e ta te on June 24.

The

c o n d itio n o f t h e m ain r o o t s o f t h i s t r e e was so s i m i l a r to
th o s e o f t r e e Dl, t h a t o n ly t h e r o o t o f t r e e Dl h a s been de­
sc rib e d .
The anatomy o f t h e m ain r o o t o f an u n t r e a t e d t r e e was
found to be e s s e n t i a l l y t h e same as t h a t o f t h e stem, w ith a
few m o d i f i c a t i o n s ( s e e F i g . 5 0 ).

The cam bial r e g io n o f t h e

r o o t a p p e a rs to be n a rro w e r t h a n t h a t o f t h e stem , and t h e
phloem i s much w i d e r .

Bands o f f i b e r s and s c l e r e i d s a re

131
much l e s s f r e q u e n t i n t h e root* and w here th e y o c c u r , t h e
hands a r e n a r ro w e r.

At t h e tim e o f e x a m in a tio n , cam hial and

phloem c e l l s w ere r i c h i n c e l l c o n t e n t s .

S ie v e tu b e s w ere

w e ll developed showing s i e v e p l a t e s , c a l l o s e , and e x tru d e d
n u c le o li.

Xylem and phloem c e l l s im m e d ia tely a d j a c e n t to

th e cam bial r e g io n were s t i l l d i f f e r e n t i a t i n g .
The c e l l s o f t h e cam bial r e g io n o f t h e t r e a t e d r o o t
seemed to be much more r i g i d th a n th o s e o f t h e u n t r e a t e d
ro o t.

The xylem c e l l s a l l a p p e a re d to be m a tu re and no

c e l l s s t i l l i n t h e p r o c e s s o f d i f f e r e n t i a t i o n co u ld be
found (s e e F ig . 5 1 ) .

A d i s t i n c t ab sen ce o f e x tru d e d n u c le ­

o l i was o b se rv e d i n t h e phloem.

S iev e p l a t e s were v e ry d i f ­

f i c u l t to l o c a t e and t h o s e t h a t were p r e s e n t were devo id o f
c a llo se .

The s ie v e t u b e s th e m se lv e s had. much s m a l l e r diam­

e t e r s when compared w ith u n t r e a t e d m a t e r i a l .

C e ll c o n te n ts

i n t h e phloem were q u i t e s c a r c e i n c o n t r a s t to t h e u n t r e a t e d
ro o t.

A few o f t h e w a l l s were a l i t t l e

d a r k e r t h a n th o s e o f

th e u n t r e a t e d c e l l s , b u t t h e r e was no i n d i c a t i o n o f c o l l a p s e
o r d i s t o r t i o n a t t h i s tim e .
being i n a dormant c o n d i t i o n .

The r o o t had t h e a p p e a ra n c e o f

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F ig . 13.
T r a n s v e r s e s e c t i o n o f t h e c a m b ia l r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , show ing p ro m in e n t s i e v e
t u b e s and s i e v e p l a t e s w i t h c a l l o s e .
One e x tr u d e d n u c l e o l u s
can be seen a t e x tre m e r i g h t o f s e c t i o n .
(205 X.)
Sample
was ta k e n 5 f e e t above t h e g ro u n d from t h e stem o f an u n ­
t r e a t e d t r e e on J u l y 30.

F i g . 14 . R a d i a l s e c t i o n o f t h e c a m b ia l r e g i o n and ad­
j a c e n t t i s s u e s o f an a sp e n ste m . S ie v e p l a t e s show ing con­
n e c t i n g s t r a n d s e n c lo s e d i n h e a v y c a l l o s e can be s e e n a t
r i g h t o f t h e s e c t i o n ; two e x t r u d e d n u c l e o l i a r e a l s o v i s i b l e .
(312 X.) Sample was t a k e n 5 f e e t above t h e groun d from t h e
s ta ii o f an u n t r e a t e d t r e e on A ugust 2 5 .

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Fig* 15. T r a n s v e r s e s e c t i o n o f t h e ca m b ial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem showing s t a r t o f phloem
and cam bial a c t i v i t y .
C e l l s a r e ex p an d in g and c o n t e n t s
c h a n g in g from a g r a n u l a r , to a s e m i - f l u i d s t a t e . Xylem i s
s t i l l in a c tiv e .
(205 X.)
Sample was ta k e n 5 f e e t above t h e
g ro u n d from t h e s t a r o f an u n t r e a t e d t r e e on A p r i l 24.

F i g . 16* T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a sp e n s t a r .
Cambium i s i n t y p i c a l
dorm ant c o n d i t i o n , c h a r a c t e r i z e d by f ir m w a l l s and r e c t a n g u ­
l a r c e l l sh a p e . A ll c e l l c o n t e n t s a r e g r a n u l a r an d d a rk i n
t h e cambium. N o te a b s e n c e o f e x t r u d e d n u c l e o l i .
(205 X.)
Sample was t a k e n 5 f e e t ab o v e t h e g roun d from t h e stem o f an
u n tre a te d tr e e .

136
F i g . 17. T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a sp e n ste m , showing a c t i v e l y d i v i d i n g
cambium, exp an ding s i e v e t u b e s , and n ew ly -fo rm ed xylem c e l l s
w ith t h i n w a l l s .
(205 X.)
Sample was ta k e n f r o m 5 f e ^ t above
t h e ground from t h e stem o f an u n t r e a t e d t r e e on May 29.

F i g . 18. T r a n s v e r s e s e c t i o n o f t h e c a m b ia l r e g i o n and
a d j a c e n t t i s s u e s o f an a sp e n stem , showing d a r k , g r a n u l a r
c e l l c o n t e n t s , n a r r o w c a m b ia l r e g i o n , and h eav y c a l l o s e f o r ­
m atio n s.
(205 X.)
Sam ple v/as t a k e n 5 f e e t above t h e ground
from t h e stem o f an u n t r e a t e d t r e e on A ugust 20.

138
Fig* 19* T r a n s v e r s e s e c t i o n o f t h e ca m b ial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , showing d i s t o r t e d c e l l s in
t h e c am b iu m , a b s e n c e o f e x t r u d e d n u c l e o l i , and v e r y t h i c k ,
d a rk c e l l w a l l s i n t h e p h lo em .
(205 X.) Sample was t a k e n 5
f e e t above t h e g ro u n d from t h e stem o f a t r e e t r e a t e d w ith
sodium m o n o c h lo r o a c e ta te on l u n e 24; sam ple was c o l l e c t e d 15
days a f t e r t r e a t i n g .

F i g . 20. T r a n s v e r s e s e c t i o n o f t h e phloem , a d j a c e n t to
t h e cam bial r e g i o n , show ing t h i c k c e l l w a l l s . S i e v e t u b e a t
r i g h t o f t h e s e c t i o n c o n t a i n s s i e v e p l a t e w ith h e a v y accumu­
la tio n of c a llo s e .
(700 X .)
S e c t i o n was made from same
sam ple as was u s e d f o r F i g u r e 1 9 .

140

F i g . 21. T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n ste m . N o te l a r g e , expanded
s i e v e tu b e s , w e ll d e f i n e d s i e v e p l a t e s w ith c o n n e c t in g
s t r a n d s , and e x tr u d e d n u c l e o l i .
(205 X.) Sample was t a k e n
5 f e e t above t h e g ro u n d from t h e stem o f an u n t r e a t e d t r e e
on J u l y 9.

F ig . 22.
T r a n s v e r s e s e c t i o n o f t h e c a m b ia l r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , show ing s e v e r e c o l l a p s e
i n t h e cambium and a d j a c e n t t i s s u e s , b la c k e n e d r a y c e l l s ,
and v o id a r e a s i n t h e p hloem .
(205 X.)
Sample was t a k e n 5
f e e t above t h e g ro u n d from t h e stem o f a t r e e t r e a t e d w i th
sodium m o n o c h lo r o a c e ta te on J u n e 24; sam ple was c o l l e c t e d 36
days a f t e r t r e a t m e n t .

142
F ig . 23* T ra n s-v e rse s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , showing b la c k e n e d , d i s ­
t o r t e d t i s s u e o f t h e c a m b ia l re g io n * N ote num erous l a c u n a e
b etw een xylern. and cambium, and l a r g e v o id s i n p h lo em .
(205 X.) Sample was t a k e n 5 f e e t abov e t h e g ro u n d from t h e
stem o f a t r e e t r e a t e d w i t h sodium m o n o c h l o r o a c e t a t e on June
24; sample was c o l l e c t e d 71 d ay s a f t e r t r e a t m e n t .

F i g . . 24. R a d i a l s e c t i o n o f cambium and phloem o f an
a s p e n stem . B la c k e n e d cambium can be see n a t e x tre m e l e f t ;
b la c k e n e d r a y c e l l s and d i s i n t e g r a t i o n o f phloem parenchym a
c e l l s can be s e e n a t t h e r i g h t o f t h e cambium.
(205 X.)
S e c t i o n made from t h e same sam p le a s u s e d f o r F i g . 25.

144
F i g . 25.
T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an asp e n ste m , showing i n t a c t c a m h ia l r e ­
g i o n and xylem; some p a re n c h y m a to u s c e l l s o f t h e phloem h av e
t h ic k e n e d w a l l s .
(205 X .)
Sam ple was ta k e n a t 5 f e e t above
t h e g r o u n d from t h e stem o f a t r e e t r e a t e d w ith 2 , 4 , 5 - T
e s t e r on Jun e 24; sam ple was c o l l e c t e d 15 days a f t e r t r e a t ­
m ent .

F i g . 26. T r a n s v e r s e s e c t i o n o f t h e ca m b ial r e g i o n and
a d j a c e n t t i s s u e s o f an a sp e n fctem, showing e a r l y s t a g e s o f
c o l l a p s e i n t h e cambium, and t h i c k - w a l l e d p a re n c h y m a to u s
c e l l s i n th e phloem .
(205 X.)
Sample was t a k e n 5 f e e t
above th e ground from t h e stem o f a t r e e t r e h t e d w ith
2 , 4 , 5 - T e s t e r on Ju n e 24; sam ple was c o l l e c t e d 56 d a y s a f t e r
tre a tm e n t.

146
F ig . 27. T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a a p e n stem , showing d e t a i l s o f t h i c k ­
ened w a lls and c o l l a p s e d c e l l s i n t h e phloem.
(700 X.)
Sec­
t i o n was made from sam ple u s e d f o r F i g u r e 26.

F i g . 28. T r a n s v e r s e s e c t i o n o f t h e c a m b ia l r e g i o n and
a d j a c e n t t i s s u e s o f t h e stem o f an a s p e n , showing ad v a n ced
s t a t e o f c o l l a p s e i n t h e cambium and a d j a c e n t phloem t i s ­
s u e s ; p aren ch y m ato u s c e l l s i n xylem h a v e b la c k e n e d c e l l con­
te n ts.
(205 X.)
Sample was t a k e n 5 f e e t above t h e g round
from th e stem o f a t r e e t r e a t e d w ith 2 , 4 , 5 - T e s t e r on Ju n e
24; sample was c o l l e c t e d 57 days a f t e r t r e a t m e n t .

148
F ig . 29. R a d i a l
ja c e n t tis s u e s o f th e
w a lls and c o n te n ts i n
S e c t i o n was made from

s e c t i o n o f t h e cam bial r e g i o n and ad­
stem o f a s p e n , showing b l a c k e n e d c e l l
t h e v i c i n i t y o f t h e cambium.
(20 5 X.)
same sam ple u s e d i n F i g u r e 28.

F ig . 30. T r a n s v e r s e s e c t i o n o f t h e c a m b ial r e g i o n and
a d j a c e n t t i s s u e o f an a s p e n stem , show ing advanced d i s i n ­
t e g r a t i o n o f cambium, and t h i c k e n e d w a l l s o f p a re n c h y m a to u s
c e l l s i n th e p hloem . N o te l a c u n a e b etw een xylem and cam­
bium.
(20 5 X.)
Sample was t a k e n from 5 f e e t ab o v e t h e
g rou nd from t h e stem o f a t r e e t r e a t e d w ith 2 , 4 , 5 - T e s t e r
on Ju n e 24; sam ple was c o l l e c t e d 71 d a y s a f t e r t r e a t m e n t .

150

F ig . 31.
T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , showing b la c k e n e d c e l l
w a l l s o f t h e c a m b ia l r e g i o n and t h i c k , b la c k e n e d w a l l s i h
t h e phloem.
(205 X.)
Sam ple was ta k e n 5 f e e t above t h e
g ro u n d from t h e stem o f a t r e e t r e a t e d w ith 2 ,4 -D e s t e r on
J u n e 24; sam ple was c o l l e c t e d 51 days a f t e r t r e a t m e n t .

F i g . 32. T r a n s v e r s e s e c t i o n o f t h e c a m b ia l r e g i o n and
a d j a c e n t t i s s u e o f an a s p e n stem , show ing num erous e x t r u d e d
n u c l e o l i , p ro m in e n t s i e v e p l a t e s , and c e l l s r i c h i n con­
te n ts.
(205 X.)
Sam ple was t a k e n 5 f e e t above t h e ground
from t h e stem o f an u n t r e a t e d t r e e on A ugust 1 4 .

152

Fig* 35.
T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n ste m , showing b la c k e n e d c e l l
c o n t e n t s o f cambium andphloem , t h i c k w a l l s i n t h e phloem ,
and c o l l a p s e o f c a m b ia l c e l l s .
(205 X.) Sample was t a k e n 5
f e e t above t h e g ro u n d from t h e stem o f a t r e e " t r e a t e d w i t h
2,4-rO e s t e r on J u n e 24; sam p le was c o l l e c t e d 71 d ay s a f t e r
tre a tm e n t.

F ig . 54. P hloem o f F i g u r e 35 a t h i g h e r m a g n i f i c a t i o n ,
show ing th ic k e n e d w a l l s , and a b s e n c e o f s i e v e p l a t e s and ex­
tru d e d n u c le o li in s ie v e tu b e s .
(700 X.)

154
F ig . 35. T r a n s v e r s e s e c t i o n o f t h e phloem, im m e d ia te ly
a d j a c e n t t o t h e c a m b ia l r e g i o n , show ing expanded s i e v e t u b e s
w ith p ro m in e n t s ie v e p l a t e s .
(700 X.) Sample was t a k e n from
5 f e e t a b o v e t h e g ro u n d from t h e stem o f an u n t r e a t e d t r e e on
Septem ber 3.

F ig . 36. T r a n s v e r s e s e c t i o n o f t h e cam b ial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , show ing e a r l y s t a g e s o f
c o l l a p s e in t h e c a m b ia l r e g i o n , b la c k e n e d phloem and xylem
r a y t i s s u e , and d i s i n t e g r a t i o n o f phloem c e l l s a d j a c e n t to
t h e cambium. (205 X.)
Sam ple was t a k e n 5 f e e t ab o v e t h e
g ro u n d from t h e stem o f a t r e e t r e a t e d w i t h sodium monoc h l o r o a c e t a t e on J u l y 3; sam ple was c o l l e c t e d 36 d a y s a f t e r
tre a tm e n t.

156
F i g . 3 7 . T r a n s v e r s e s e c t i o n o f t h e cam hial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , showing i n t a c t c e l l w a l l s
i n t h e cambium and xylern, and e a r l y s t a g e s o f c o l l a p s e i n
t h e phloem . U o te t h e d a r k e n e d c e l l c o n t e n t s i n t h e xylem
and phloem .
(205 X .)
Sample was t a k e n 5 f e e t abov e t h e
g ro u n d from t h e stem o f a t r e e t r e a t e d w ith 2 , 4 , 5 - T e s t e r on
J u l y 15; sam ple was c o l l e c t e d 36 days a f t e r t r e a t m e n t .

F ig . 38. T r a n s v e r s e s e c t i o n o f t h e ca m b ial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n stem , showing no e v i d e n c e o f
damage from c h e m ic a l t r e a t m e n t .
(205 X.)
Sample was t a k e n
5 f e e t above t h e g ro u n d from t h e stem o f a t r e e t r e a t e d w ith
2 ,4 -D on J u l y 15; sa m p le was c o l l e c t e d 36 days a f t e r t r e a t ­
m ent .

158

F ig . 39. T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n an d
a d j a c e n t t i s s u e s o f an a s p e n stem , show ing c o l l a p s e o f cambium and phloem p a ren ch y m a c e l l s adjacen_t to cambium.
(205 X.) Sample was t a k e n 18 i n c h e s above t h e g ro u n d from
t h e stem o f a t r e e t r e a t e d w ith 2 , 4 , 5 - T e s t e r on dune 4;
sam ple was co3.1ected 80 d a y s a f t e r t r e a t m e n t .

F ig . 40.
T r a n s v e r s e s e c t i o n o f t h e ca m b ial r e g i o n and
a d j a c e n t t i s s u e s o f t h e stem o f an a s p e n .
C o n d itio n o f t h i s
s e c t i o n i s co m p a ra b le t o t h a t o f F i g u r e 3 9.
(20 5 X.)
Sample
was tak en a t 5 f e e t from same t r e e a s u s e d f o r F i g u r e 3 9 .

160

F ig . 41* T r a n s v e r s e s e c t i o n o f t h e eam bial r e g i o n and
a d j a c e n t t i s s u e s o f t h e stem o f an a s p e n . Cambium a n d xylem
a r e i n t a c t ; e a r l y s t a g e s o f c o l l a p s e and some w a l l t h i c k e n ­
i n g v i s i b l e i n p h lo e m .
(205 X .)
Sample was t a k e n 55 f e e t
above t h e g ro u n d from t h e same t r e e a s u se d i n F i g u r e s 39
and 4 0 .

F ig . 42. T r a n s v e r s e s e c t i o n o f t h e t i p o f t h e l e a d e r
o f an aspen stem , show ing c o m p l e t e l y b la c k e n e d and c o l ­
l a p s e d cambium. Xylem i s d i s t o r t e d and phloem i s b l a c k e n e d
and d i s t o r t e d . N o te i n t a c t f i b e r s and s c l e r e i d s i n p h lo e m .
(205 X.) Sample was t a k e n from t h e l e a d e r o f t h e same t r e e
a s u s e d f o r F i g u r e s 39, 40, and 41.

162

F ig , 43. T r a n s v e r s e s e c t i o n o f tiie cam b ial r e g i o n and
a d ja c e n t t i s s u e s o f an a sp e n stem , showing ad v a n ced s t a g e o f
d i s i n t e g r a t i o n o f c a m b ia l c e l l s , la c u n a e betw een xylem and
cambium, and t h i c k paren ch ym a w a l l s i n t h e phloem .
(205 X.)
Sample was t a k e n from 5 f e e t above t h e grou nd from t h e stem
o f a t r e e t r e a t e d w i t h a d o u b le s t r e n g t h s o l u t i o n o f 2 , 4 , 5 - T
e s t e r on dune 24; sam p le was c o l l e c t e d 71 days a f t e r t r e a t ­
m e n t.

164F ig . 44. T r a n s v e r s e s e c t i o n o f a tw ig from an u n t r e a t e d
t r e e ; c o l l e c t e d on A u g u st 18 and show ing xylem, cambium,
phloem, and h a r k c e l l s .
(205 X .)

F ig . 45. T r a n s v e r s e s e c t i o n o f a tw ig from a t r e e
t r e a t e d w ith 2 ,4 -,5 -T e s t e r on J u l y 9 . Sample was c o l l e c t e d
40 days a f t e r t r e a t m e n t .
S e c t i o n shows c o m p le te ly c o l l a p s e d
cambium, b la c k e n e d and d i s i n t e g r a t e d phloem parenchym a
c e l l s , and some b l a c k e n e d p i t h c e l l s .
(205 X.)

166
F ig. 46. T r a n s v e r s e s e c t i o n o f t h e m id rib p o r t i o n o f
an aspen l e a f , show ing v a s c u l a r b u n d le , b u n d le s h e a th , an d
su rro u n d in g c e l l s .
(205 X .)

F ig . 47. T r a n s v e r s e s e c t i o n o f t h e l e a f b l a d e immedi­
a t e l y a d ja c e n t to t h e m i d r i b s e c t i o n o f F ig u r e 4 6 . E p i­
derm al l a y e r s , p a l i s a d e l a y e r s , and spongy m e s o p h y ll a r e
v i s i b l e . N ote p r o m in e n t c h l o r o p l a s t s i n p a l i s a d e l a y e r s and
spongy m eso p h y ll.
(20 5 X.)

168

f i g . 48. T r a n s v e r s e s e c t i o n o f t h e m id rib o f a l e a f
from an aspen t r e e t r e a t e d w i t h 2 ,4 -D e s t e r on Tni v q.
sam ple was c o l l e c t e d 40 d a y s a f t e r t r e a t m e n t
Onrnnie+ew
blackened and d i s i n t e g r a t e d phloem i s v i s i b l 4 w i t h i n
c u l a r bundle. B la c k e n e d r a y c e l l s i n t h e x y L ^ ^ d b l *
h e e s e ? “ en( 2 0 t ax ? r ° e l l S ° U tS ld e t h e b u n d l* sh ea ?S can ^ o

F ig . 49. P o r t i o n o f l e a f "blade a d j a c e n t to t h e m i d r i b
d e s c r ib e d i n F i g u r e 48. A l l c e l l s o f p a l i s a d e l a y e r and
spongy m esop hyll a r e b l a c k e n e d and d i s t o r t e d e x c e p t f o r a
few i n t a c t f i b e r s .
(205 X.)

170

F ig . 50. T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n r o o t , showing e x tru d e d n u c l e o l i ,
e x p a n d e d s ie v e t u b e s , and p ro m in e n t s i e v e p l a t e s .
Sample
was taken from t h e m ain r o o t o f an u n t r e a t e d t r e e , a b o u t 18
i n c h e s from t h e r o o t c o l l a r .
Sam ple was c o l l e c t e d on Septem ­
b e r 5.

F ig . 51. T r a n s v e r s e s e c t i o n o f t h e cam bial r e g i o n and
a d j a c e n t t i s s u e s o f an a s p e n r o o t , show ing c o n t r a c t e d ap­
p e a r a n c e o f s i e v e t u b e s , a b s e n c e o f e x t r u d e d n u c l e o l i , and
la c k o f v is ib le s ie v e p l a t e s .
(205 X .)
Sample was t a k e n
from th e main r o o t o f an a sp e n t r e e t r e a t e d w ith 2 ,4 , 5-T
e s t e r on Tune 4 . Sample was c o l l e c t e d 80 days a f t e r t r e a t ­
m e n t.

V II.

DISCUSSION AND CONCLUSIONS

A. D isc u ssio n
1 . F i e l d O b s e r v a tio n s
E f f e c t s o f chem ical t r e a tm e n t on t h e ap p e a ra n c e o f
t r e e s and c o n d i t i o n o f t h e b a r k .
r e s u l t e d i n d e a th o f t h e t r e e s .

A ll chem ical t r e a tm e n t s
However, t h e speed o f k i l l ­

in g and t h e e x t e n t o f b ark lo o s e n in g o b ta in e d w ere q u i t e
d iffe re n t.
Sodium mo no c h lo ro a c e t a t e a p p lie d i n f r i l l s was t h e
f a s t e s t - a c t i n g ch e m ic a l.

The le a v e s o f t r e e s t r e a t e d by

t h i s method t u r n e d from g re e n to brovm w ith in a few days and
had f a l l e n from most t r e e s by th e end o f 23 days.

Bark o f

t h e stem t u r n e d a s o l i d b la c k c o l o r w i t h i n a r e l a t i v e l y
s h o r t tim e and co u ld be s t r i p p e d from t h e stem to a h e i g h t
o f ab o u t 7 f e e t above t h e ground when examined 71 days a f t e r
tre a tin g .
B asal s p ra y s o f 2 , 4 , 5-T e s t e r and 2,4-D e s t e r were th e
o n ly o t h e r t r e a t m e n t s t h a t showed e x te n s iv e i n j u r y d u rin g
summer and autumn im m e d ia tely fo llo w in g t r e a t m e n t .

Sodium

mono c h lo ro a c e t a t e a p p l ie d to a p e e le d g i r d l e d id i n j u r e some
t r e e s q u i t e s e v e r e l y b u t m ost o f t h e damage o c c u rre d t h e

173
year a f te r tre a tin g .

O th e r t r e a t m e n t s were o n ly p a r t i a l l y

e f f e c t i v e , even one y e a r a f t e r t r e a t m e n t .
The l e a v e s o f t r e e s t r e a t e d w ith 2 , 4 , 5-T and 2,4 -D
t u r n e d a b r i l l i a n t r e d and y e llo w f o r a b o u t 3 weeks b e f o r e
c h a n g in g to brown and rem ained a t t a c h e d to t h e t r e e much
l o n g e r th a n th o s e o f t r e e s t r e a t e d w ith sodium m onochloroa c e ta te in f r i l l s .

The b ark o f th e stems became d i s c o l o r e d

i n sm all a r e a s a t f i r s t .

These a r e a s l a t e r c o a le s c e d and

t h e o u t e r b a rk became a s o l i d o ra n g e c o l o r .
A lthough t h e a p p e a ra n c e o f t r e e s t r e a t e d w ith 2 , 4 , 5-T
and 2,4 -D was q u i t e s i m i l a r , th e k i l l i n g e f f e c t o f t h e
2 , 4 , 5-T t r e a t m e n t was much more r a p i d , and b ark lo o s e n in g
more p ro n o u n ced .

The b ark o f th e sp ray e d a r e a o f t r e e s

t r e a t e d w ith 2 , 4 , 5-T was f a i r l y l o o s e when i n s p e c t e d 71 days
a f t e r t r e a t i n g , b u t t h e re m ain d er o f th e stem b a rk was
tig h t.

On 2,4 -D t r e a t e d t r e e s , t h e bark was s t i l l t i g h t 71

days a f t e r t r e a t m e n t , even on th e sp ray e d a r e a s .
An ex a m in atio n

made one y e a r a f t e r t r e a t i n g showed

t h a t m ost t r e e s t r e a t e d w ith sodium mono c h lo ro a c e t a t e i n
f r i l l s and t r e e s t r e a t e d w ith 2 , 4 , 5-T e s t e r c o u ld be p e e le d .
On t h e o t h e r hand, many t r e e s t r e a t e d w ith 2,4-D s t i l l r e ­
s is te d p e e lin g .
The e f f e c t i v e n e s s o f t r e a t m e n t s when a p p lie d on d i f f e r ­
ent d a te s .

The d a te o f t r e a t i n g d id have some e f f e c t on t h e

s p e e d and e f f e c t i v e n e s s o f chem ical t r e a t m e n t s .

I t was found

174
th a t e a r ly tre a tm e n ts,

even b e f o r e b u d -b re a k , were j u s t a s

q u ic k and e f f e c t i v e i n t h e i r a c t i o n as th o s e which were ap­
p l i e d when t r e e s were i n f u l l l e a f .

T re atm e n ts made l a t e r

th a n J u l y 3 to o k l o n g e r to k i l l t r e e s and were l e s s e f f e c ­
t i v e i n lo o s e n i n g t h e b a rk th a n t r e a t m e n t s a p p lie d e a r l i e r .
T his was e s p e e i a l l j r t r u e o f t r e e s t r e a t e d w ith 2 , 4 , 5-T o r
2,4 -D .

T re e s t r e a t e d w ith sodium m o n o c h lo ro a c e ta te a f t e r

J u l y 3 d id n o t d i e a s f a s t as th o s e t r e a t e d e a r l i e r in th e
s e a s o n , b u t t h e b a rk p e e le d i n Septem ber j u s t as e a s i l y as
i t d id from t h e t r e e s w ith t h e e a r l i e r t r e a t m e n t s .
M i s c e lla n e o u s o b s e r v a t i o n s .

E xam inations made on t h e

r o o t s o f t r e a t e d t r e e s f a i l e d to d i s c l o s e any damage.

R oots

o f t r e e s t r e a t e d w i th sodium mono c h lo ro a c e t a t e were i n s p e c t ­
ed 71 days a f t e r t h e chem ical was a p p lie d , and t h e r o o t s o f
t r e e s t r e a t e d w ith 2 , 4 , 5-T e s t e r were examined 80 days a f t e r
tre a tm e n t.

I n bo th i n s t a n c e s th e r o o t s ap peared to be

h e a l t h y , a lth o u g h t h e t r e e s a p p a r e n t l y were dead down to t h e
ro o t c o lla r.
A ll chem ical t r e a t m e n t s were more e f f e c t i v e i n t h e low­
e r h a l f o f t h e t r u n k th a n th e y were i n th e u p p e r h a l f .
Pulpwood s t i c k s o b t a i n e d from t h e lo w er r e g io n o f t h e t r u n k s
u s u a l l y p e e le d much e a s i e r th a n th o s e o b t a in e d from t h e up­
per p o rtio n .

T his was t r u e f o r a l l chemical t r e a t m e n t s b u t

was e s p e c i a l l y pronou nced i n s t i c k s o b ta in e d from t r e e s
t r e a t e d w ith 2 , 4 , 5-T and 2,4 -D .

17 5
I t was n o te d t h a t asp e n t r e a t e d w ith sodium m onochloroa c e t a t e i n f r i l l s d ie d f a s t e r and e v e n t u a l l y p e e le d b e t t e r
th a n t h a t t r e a t e d w ith t h e same ch em ical a p p l i e d to a p e e le d
g ird le .

I t waB a ls o found t h a t f r i l l s which had been c u t

i n t o t h e sapwood f o r a t l e a s t o n e - h a l f in c h were more e f f e c ­
t i v e th a n t h o s e which b a r e l y sco re d t h e wood.
Very l i t t l e t r a n s l o c a t i o n i n th e l a t e r a l d i r e c t i o n was
found i n t h e c a s e o f sodium mono c h lo ro a c e t a t e .

T rees

f r i l l e d and t r e a t e d on one s i d e o f t h e stem showed stem i n ­
j u r y on t h e same s i d e o n ly .

These f i n d i n g s a r e i n agreem ent

w ith t h o s e o f o t h e r w o rk e rs ( 8 0 ,6 5 ) .
A llow ing t r e a t e d t r e e s to s ta n d o v e r w i n t e r b e f o r e
f e l l i n g and p e e l i n g was found to in c r e a s e g r e a t l y t h e e f f e c ­
tiv e n e s s o f tre a tm e n ts.

I n many c a s e s th e bark c o n ta in e d

lo n g v e r t i c a l s p l i t s and was slo u g h in g o f f n a t u r a l l y when
examined one y e a r a f t e r t r e a t m e n t .

However, I t was a ls o

d is c o v e r e d t h a t s t a n d i n g o v e r w i n t e r caused a d i s c o l o r a t i o n
i n t h e o u t e r one In ch o f sapwood.

T his d i s c o l o r a t i o n i s un­

d e s i r a b l e f o r c e r t a i n ty p e s o f p a p e r p ro d u c ts , s in c e a d d i­
t i o n a l amounts o f b le a c h m ust be u se d in o r d e r to produce a
p u re w h ite p r o d u c t.

176
2. A natom ical Changes i n t h e T is s u e s o f Stems, Twigs,
L e a v e s , and R o o ts.
a.

P r o g r e s s i v e e f f e c t s o f chem ical t r e a tm e n t s on th e cam bial
Region and a d j a c e n t t i s s u e s o f t h e stem .
E f f e c t s o f sodium mono ch lo ro a c e t a t e .

C e l l s o f t h e cam­

b i a l r e g io n w ere d i s t o r t e d and p a r t i a l l y c o l l a p s e d 15 days
a f te r tre a tm e n t.

C ell c o n te n ts became darlc and, a s more

tim e e l a p s e d , c e l l c o l l a p s e became g e n e r a l and v e ry s e v e re
th ro u g h o u t t h e r e g i o n .

T his was fo llo w e d by d i s i n t e g r a t i o n

o f c e l l w a l l s and c o n t e n t s .

E v e n tu a lly t h e e n t i r e cam bial

re g io n was tra n s fo rm e d i n t o t a n g e n t i a l bands o f b la c k e n e d ,
s t r u c t u r e l e s s c e l l w a l l s and c e l l c o n t e n t s .

T his c o n d itio n

can be o b se rv e d i n F ig u re 23.
The m a tu re v e s s e l s and f i b e r s o f t h e xylem were n o t a f ­
f e c t e d by t h e t r e a t m e n t .

On t h e o t h e r hand, t h e w a l l s o f

n ew ly -fo im ed xylem e lem en ts showed s ig n s o f c o l l a p s e 15 days
a f t e r tre a tm e n t.

T h is c o n d itio n became more pronounced un­

t i l c o l l a p s e was g e n e r a l i n t h i s p a r t o f t h e xylem, fo llo w e d
by c e l l w a ll d i s i n t e g r a t i o n .

The r e s u l t was t h e appearance

o f numerous la c u n a e between xylem and t h e cam bial r e g io n .
Ray and l o n g i t u d i n a l parenchyma c e l l s o f t h e xylem f r e q u e n t ­
l y e x h i b i t e d b la c k e n e d w a l l s and c o n t e n t s , a lth o u g h t h e s e
c e l l s c o l l a p s e d o n ly im m ed iately a d ja c e n t to t h e cam bial r e ­
g io n .

177
The phloem was s e v e r e l y a t t a c k e d , even as e a r l y a s 15
days a f t e r t r e a t m e n t .

The w a lls o f m ost parenchym atous

c e l l s "became "blackened and i n c r e a s e d i n t h i c k n e s s ;

c e lls

were t w i s t e d and d i s t o r t e d , and i n p a r t i a l c o l l a p s e .

L a te r

on, c o l l a p s e "became s e v e re , e s p e c i a l l y in th e s i e v e t u b e s ,
and th e n a g r a d u a l d i s i n t e g r a t i o n took p l a c e .

This d i s i n ­

t e g r a t i o n became p r o g r e s s i v e l y g r e a t e r , and a f t e r 71 days
l a r g e v o id s w ere formed between bands c o n s i s t i n g o f i n t a c t
f i b e r s and s c l e r e i d s and rem ain in g parenchym atous c e l l s .
S ie v e p l a t e s w ere v e r y d i f f i c u l t to d e t e c t i n t h e t r e a t e d
se c tio n s .

T h is a p p a r e n t l y was due to t h e f a c t t h a t t h e

w a l l s c o n t a i n i n g t h e p l a t e s were th ic k e n e d and l i n e d w ith
dark cy to p lasm which masked th e p l a t e s .

The p l a t e s were a l -

i

so d ev o id o f c a l l o s e i n many i n s t a n c e s , which made t h e i r de­
t e c t i o n more d i f f i c u l t .

E xtru ded n u c l e o l i were v ery r a r e .

I n many c a s e s none c o u ld be found i n t h e e n t i r e phloem.

The

a b s e n c e o f s ie v e p l a t e s and e x tru d e d n u c l e o l i can be seen i n
F ig u r e 25.

Ray and l o n g i t u d i n a l parenchyma c e l l s o f t h e

phloem became b la c k e n e d and d i s t o r t e d a s a r e s u l t o f t r e a t ­
m en t.

I n many c a s e s r a y s d i s i n t e g r a t e d in t h e v i c i n i t y o f

t h e cam bial r e g io n and assumed a t w i s t e d ap p e aran c e th ro u g h ­
o u t t h e r e s t o f t h e phloem (s e e F ig . 2 2 ).
The u l t i m a t e e f f e c t s o f t h i s c h e m ic a l, as seen 71 days
a f t e r t r e a t i n g , w ere com plete c o l l a p s e o f th e cam bial r e ­
g io n , c o l l a p s e o f new ly -fo im ed xylem elem en ts, s e v e re c o l-

178
laps© o f some parenchym atous c e l l s i n t h e phloem, and d i s i n ­
t e g r a t i o n o f o th e r s *
t h e phloem*

Numerous l a r g e v o id s were p r e s e n t i n

The o n ly c e l l s t h a t rem ained i n t a c t were f i b e r s

and s c l e r e i d s i n t h e phloem, and v e s s e l s and f i b e r s i n t h e
2 C y l0 3 1 .

E f f e c t s o f 2 . 4 , 5-T e s t e r .

The e f f e c t s o f 2 , 4 , 5-T e s t e r

were q u i t e s i m i l a r to t h o s e o f sodium mono c h lo ro a c e t a t e b u t
much l e s s sev ere*

The chem ical d id n o t i n j u r e t h e c e l l s a s

f a s t as t h e sodium mono c h lo ro a c e t a t e d id , and when sam ples
o f t h e tw> t r e a t m e n t s w ere c o l l e c t e d on t h e same day, and a
com parison made, t h e 2 , 4 , 5-T sample was always a f f e c t e d
le ss.
P i f t e e n days a f t e r t r e a t i n g , o n ly a few parenchym atous
c e l l s o f t h e phloem were damaged.

These h ad th ic k e n e d w a l l s

and dark c e l l c o n t e n t s b u t no c o l l a p s e co uld be d e t e c t e d .
No damage to t h e cam bial re g io n o r xylem could be seen.
E v e n tu a l l y t h e cam bial r e g io n d id c o l l a p s e , b u t 71 days
a f t e r tr e a tm e n t v e r y l i t t l e c o l l a p s e had o c c u r r e d in e i t h e r
t h e phloem o r xylem a s compared w ith t h e sample from t h e
t r e e t r e a t e d w ith sodium m o n o c h lo ro a c e ta te .

P ro b a b ly t h e

g r e a t e s t s i n g l e d i f f e r e n c e between t h e two t r e a tm e n t s was
t h e a p p e a ra n c e o f t h e phloem.

The amount o f c o l l a p s e and

d e s t r u c t i o n n e v e r became as g r e a t i n t h e 2 , 4 , 5-T t r e a t e d
sam p les.

P aren chym ato us c e l l s dev elo p ed v ery t h i c k w a lls

and t h e c a v i t i e s w ere v e ry sm all i n comparison w ith u n t r e a t -

179
ed c e l l s .

However, m ost c e l l w a l l s r e t a i n e d a rounded o r

o v a l a p p e a ra n c e , even 7JL days a f t e r t r e a t i n g .

Very few

v o i d s d ev elo p ed i n t h e phloem o f 2 , 4 , 5-T t r e a t e d t r e e s .
E f f e c t s o f 2,4 -D e s t e r .

The e f f e c t s o f 2,4-D were a l ­

m o st i d e n t i c a l to t h o s e o f 2 , 4 , 5-T .

The d e g re e o f i n j u r y

was l e s s i n

2 ,4 -D sam ples th a n in th o s e o f 2 , 4 , 5-T c o l l e c t e d

a t t h e same

tim e . I n j u r y to most c e l l s s t a r t e d a t a l a t e r

d a te and n e v e r was as s e v e re as 2 ,4 , 5-T i n j u r y .
Comments.

■-

The b la c k e n in g o f c e l l c o n te n ts and w a l l s ,

as d e s c r i b e d f o r t h e s e t h r e e t r e a t m e n t s , i s th o u g h t by some
i n v e s t i g a t o r s to be caused by a r e l e a s e o f ta n n in and p h lo baphene compounds by d ying ra y and l o n g i t u d i n a l parenchyma
c e l l s (51) .

D a r k - s ta in e d s ie v e tu b e c o n te n ts have been i n ­

t e r p r e t e d a s t h e r e s u l t s o f d i s o r g a n i z a t i o n o f t h e cytoplasm
(57) .
The th ic k e n e d w a l l s o f t h e phloem p ro b a b ly were caused
by a co m bination o f a c t u a l w a ll th ic k e n in g and a l i n i n g o f
cytoplasm s t a i n e d

t h e same a s t h e w a ll, due to a c t i o n o f t h e

c h e m ic a ls . T his c o n d i t i o n can be

o b se rv e d i n F ig u r e s 27 and

55.
The absence o f c a l l o s e on s i e v e p l a t e s and t h e d is a p ­
p e a ra n c e o f e x tru d e d n u c l e o l i i n s ie v e tu b e s have been a s s o ­
c i a t e d w ith d e c re a s e d a c t i v i t y o f t h e phloem ( 2 8 ,2 9 ) .
was p ro b a b ly t h e c a s e w ith t h e t r e a t e d t r e e s .

T his

The phloem

was a p p a r e n t l y i n a s t a t e o f d e c re a s e d a c t i v i t y as a r e s u l t

180
o f a p p ro a c h in g d e a th , c a u sin g an ab se n ce o f e x tru d e d n u c l e ­
o l i and c a l l o s e m a t e r i a l .

T his c o n d i t i o n was a c o n s ta n t

f e a t u r e o f p r a c t i c a l l y e v e ry sample which d is p la y e d o t h e r
s ig n s o f i n j u r y due to chem ical t r e a t m e n t .
b . The e f f e c t i v e n e s s o f ch e m ica ls when a p p lie d on d i f f e r e n t
d a te s.
Sodium mono c h lo ro a c e t a t e . Based on an ex am in atio n o f
sam ples ta k e n 56 days a f t e r tr e a tm e n t, i t was found t h a t t h e
Ju n e 24 a p p l i c a t i o n produced t h e g r e a t e s t amount o f damage.
The J u l y 5 t r e a t m e n t was n e x t i n e f f e c t i v e n e s s and t h e J u l y
9 t r e a tm e n t was l e a s t e f f e c t i v e .

However, even though t h e

d eg ree o f i n j u r y was n o t as g r e a t f o r t h e l a s t two d a t e s , i t
was s t i l l q u i t e s e v e re and t h e t r e a tm e n ts w ere judged s a t i s ­
fa c to ry .
2 , 4 , 5-T e s t e r .
t e n s i v e damage.

Only t h e June 24 tr e a tm e n ts showed ex­

The J u l y 3 tr e a tm e n t was n e x t i n e f f e c t i v e ­

n e s s , and t r e a t m e n t s made on J u l y 9 and J u ly 15 showed v e ry
l i t t l e damage.
2,4 -D e s t e r .

The 2,4 -D t r e a tm e n t s fo llo w e d t h e same

p a t t e r n a s t h e 2 , 4 , 5-T t r e a t m e n t s .

The d egree o f i n j u r y was

l e s s i n t h e s e sam ples and no damage o f any k i n d co u ld be
found i n t h e J u l y t r e a t m e n t s .
Comments.

The r e s u l t s o f t h i s study a r e r e l a t e d some­

what to t h e o b s e r v a t i o n s made by o t h e r w o rk e rs.

181
W ilcox (7 2) r e p o r t e d t h a t n a t u r a l p e e l i n g o f t r e e s i n
New York S t a t e was e a s i e s t when t h e mean te m p e r a tu r e was
above 40 d e g re e s F a h r e n h e i t .

He a ls o o b se rv e d t h a t t h e pen­

e t r a t i o n o f an a r s e n i c s o l u t i o n in to t h e sapwood was m ost
r a p i d d u rin g t h e h e i g h t o f t h e s a p - p e e li n g s e a so n .
C z a b a to r

(21.) , w orking on t h e same exp erim ent w ith Wil­

cox, o b s e rv e d t h a t t h e b e s t chem ical t r e a tm e n t o f hardwoods
r e s u l t e d when t h e ch em ical was a p p l ie d between May 50 and
J u ly 1 .
I t i s e v id e n t t h a t a lth o u g h th e av e rag e te m p e r a tu r e
m ust be above a c e r t a i n p o i n t f o r s u c c e s s f u l chem ical t r e a t ­
m en t, i t i s n o t t h e d e c id in g f a c t o r .

O b s e rv a tio n s made on

th e stem s o f u n t r e a t e d asp en show t h a t t h e cam bial r e g io n i s
m ost a c t i v e betw een May 29 and J u ly 1 .

On t h e b a s i s o f

t h e s e f i n d i n g s and t h o s e summarized above f o r t r e a t e d t r e e s ,
i t would a p p e a r t h a t s u c c e s s o f t r e a tm e n t c o in c id e s more
c l o s e l y w ith cam bial a c t i v i t y r a t h e r th a n changes i n tem per­
a t u r e a lo n e .
c . The e f f e c t s o f 2 , 4 , 5-T e s t e r a t d i f f e r e n t h e i g h t s i n th e
tru n k .
By t a k i n g sam ples from d i f f e r e n t h e i g h t s i n t h e tr u n k ,
i t was found t h a t o n ly t h e sam ples from t h e lo w e r 10 f e e t
and from th e t i p o f t h e l e a d e r showed damage to any d e g re e .
The sam ples from t h e p o r t i o n between 10 f e e t above th e

182

ground and t h e to p showed v e r y l i t t l e damage.

T h is can he

se e n by com paring F ig u r e s 59, 41, and 42.
d. M i s c e lla n e o u s d a ta
D o u b le _ s tre n g th 2 , 4 , 5-T s o l u t i o n .

No d i f f e r e n c e co u ld

b e d e t e c te d i n t h e d eg ree o f i n j u r y caused by s i n g l e s t r e n g t h
and d o u b le s t r e n g t h 2 , 4 , 5-T e s t e r .

Samples ta k e n t h e same

number o f days a f t e r t r e a t i n g , showed a p p ro x im a te ly t h e same
amount o f damage.

The a p p e a ra n c e o f t h e stem sam ples 71

days a f t e r t r e a tm e n t can be seen by com paring F ig u r e s 50 and
45.
E f f e c t s o f c h e m ic a ls on tw ig s and l e a v e s .

The l e a v e s

and tw ig s o f t r e a t e d t r e e s showed v e ry s e v e re i n j u r y due to
chem ical t r e a t m e n t .

I n a l l ca se s e x te n s iv e c o l l a p s e and

d i s i n t e g r a t i o n o c c u r r e d , sometimes b e f o r e damage to th e
tru n k c o u ld be d e t e c t e d .
I t i s p o s s i b l e t h a t t h e g r e a t e s t amount o f t h e chem ical
i s t r a n s p o r t e d up to t h e l e a v e s b u t i s n o t c a r r i e d back down
b ec au se o f t h e d eath o f t h e l e a v e s and phloem t i s s u e o f t h e
tw ig s im m e d ia tely b elow t h e l e a v e s .

T his assu m p tio n ,

co u p led w ith t h e f a c t t h a t th e lo w e r p o r t i o n o f t h e t r u n k i s
u s u a l l y s a t u r a t e d w ith t r e a t i n g s o l u t i o n , may e x p l a in why th e
b ase o f t h e t r e e s and t h e to p s a r e damaged more s e v e r e l y
th a n t h e i n t e r v e n i n g p o r t i o n s .
E f f e c t o f ch em ical t r e a tm e n t s on r o o t s .

An ex am in atio n

o f r o o t sam ples showed a d i s t i n c t ab se n ce o f e x tru d e d n u c le ­

183
o l i and s i e v e p l a t e s i n t h e phloem.

I t was a ls o n o te d t h a t

t h e d ia m e t e r s o f t h e s i e v e tu b e s were n o t as l a r g e a s th o s e
o f u n t r e a t e d sam p les.

The phloem showed no o t h e r i n j u r y .

T here was n o t much a c t i v i t y i n t h e cambial r e g i o n , b u t i t
d id n o t show any damage.

Xylera d id n o t a p p e a r to be dam­

ag ed .

B. C o n clu sio n s
E f f e c t i v e n e s s o f ch e m icals as .debarking a g e n t s .

Sodium

m o n o c h lo ro a c e ta te a p p l i e d i n f r i l l s was th e m ost e f f e c t i v e
chem ical u se d In t h i s stud y f o r t h e p u rp o se o f l o o s e n in g t h e
b a rk o f a s p e n .

However, good r e s u l t s can o n ly be a c h ie v e d

by a llo w in g t r e a t e d t r e e s to s ta n d o v e r w i n t e r ; t h e b ark o f
some o f t h e u p p e r s t i c k s was t i g h t even a f t e r s ta n d in g f o r
one y e a r .
2 , 4 ,5 - T e s t e r , a p p l i e d as a b a s a l sp ray , was f a i r l y e f ­
f e c t i v e a s a d eb a rk in g a g e n t.

S t i c k s from th e lo w e r p o r t i o n

o f t h e t r u n k s c o u ld be p e e le d a f t e r t h e t r e e s had rem ained
s ta n d in g o v e r w i n t e r , b u t n o t as e a s i l y as t h o s e o f t r e e s
t r e a t e d w ith sodium mono c h lo ro a c e t a t e .

The o c c u r r e n c e o f

t i g h t b a rk on t h e u p p e r s t i c k s was found to be more common
on 2 ,4 , 5 - T t r e a t e d t r e e s th an on th o s e t r e a t e d v dth sodium
m o n o c h lo r o a c e ta te .

F u r t h e r s t u d i e s on m ethods o f a p p l i c a ­

t i o n a r e n eed ed to o b t a i n t h e b e s t r e s u l t s w ith t h i s chem­
ic a l.

184
2,4-D e s t e r was n o t a s a t i s f a c t o r y chem ical f o r t h e
chem ical d e b a rk in g o f a s p e n .

The r e s u l t s were too i n c o n ­

s i s t e n t to w a r r a n t f u r t h e r stu d y .
Bark lo o s e n i n g due to chem ical a c t i o n .

The r e s u l t s o f

t h i s s tu d y s u g g e s t t h a t bark l o o s e n in g i s caused by a com­
b i n a t i o n o f c h e m ica l and p h y s i c a l changes o c c u r r i n g i n t h e
cam bial r e g io n and a d j a c e n t t i s s u e s o f t h e t r e e stem.

The

c o l l a p s e o f n ew ly-form ed xylem c e l l s and t h e accompanying
la c u n a e , i n c o n ju n c tio n w ith c o l l a p s e and d i s i n t e g r a t i o n o f
cam bial and phloem c e l l s ,

e v i d e n t l y r e s u l t s i n t h e fo rm a tio n

o f a b e l t o f weakened m a t e r i a l ,

c o n s i s t i n g o f rem nants o f c e l l

w a l l s and c e l l c o n t e n t s , which can be r u p tu r e d v e r y e a s i l y .
C o lla p s e o f c e l l s seems to be p a r t i a l l y caused by a c o n t r a c ­
t i o n o f t h e e n t i r e phloem r e g i o n .

T h is c o n t r a c t i o n i s e v i ­

d e n t l y r e s t r a i n e d toy t h e xylem, c a u sin g t h e lo n g v e r t i c a l
s p l i t s to o c c u r i n t h e b ark a f t e r t r e a t m e n t .
E f f e c t o f ch o m icals on r o o t s .
have l i t t l e

The chem icals ap p e a r to

e f f e c t on t h e r o o t s and a p p a r e n tl y a r e n o t

t r a n s l o c a t e d from a t r e a t e d t r e e to a h e a l t h y o n e .

In s p ite

o f t h e changes r e p o r t e d i n r o o t sam ples, no ev id ence o f dam­
age to a d j a c e n t t r e e s c o u ld be d e t e c te d two y e a rs a f t e r
tre a tm e n t.

I n view o f t h e f a c t t h a t m ost aspen t r e e s o r i g i ­

n a t e a s s u c k e rs and a r e connected by an e x t e n s i v e l a t e r a l
r o o t system

(22) , i t would seem t h a t any damage to a d j a c e n t

t r e e s sh o u ld h ave been a p p a r e n t w ith in t h i s p e r i o d o f ti m e .

185
L im ita tio n o f tr e e s i z e .

There a p p a r e n t l y i s a maximum

t r e e stem d ia m e te r , beyond which t h e c h e m ic a ls u se d i n t h i s
s tu d y l o s e t h e i r e f f e c t i v e n e s s .

I n a lm o st e v e ry group o f

t r e a t e d aspen w here one o r two I n d i v i d u a l s rem ained h e a l t h y ,
th e y were t r e e s o f 10 in c h e s o r more i n d ia m e te r a t b r e a s t
h e ig h t.

«

T h is was t r u e even where a d d i t i o n a l s o l u t i o n had

been a p p l i e d to com pensate f o r t r e e s i z e .
P e e l i n g c h a r a c t e r i s t i c s o f t r e e s t r e a t e d w ith chem­
ic a ls.

The b a rk o f many t r e e s t r e a t e d w ith sodium mono-

c h l o r o a c e t a t e b re a k s up i n t o sm all fra g m e n ts when i t i s
p e e le d from t h e t r e e .

T his a p p a r e n t l y i s caused by s e v e re

d i s i n t e g r a t i o n o f t h e phloem .

T his re g io n was found so com­

p l e t e l y d i s i n t e g r a t e d 71 days a f t e r t r e a tm e n t t h a t i n many
p l a c e s o n ly i s o l a t e d g ro u p s o f f i b e r s and s c l e r e i d s were i n ­
ta c t.

T his r e s u l t s i n bark crum bling when i t i s p u l l e d o f f

t h e t r e e , a llo w in g t h e lo n g s t r a n d s o f i n t a c t f i b e r s and
s c l e r e i d s to rem ain a t t a c h e d to t h e t r u n k .
The b ark o f t r e e s t r e a t e d w ith 2 ,4 -D e s t e r and 2 , 4 , 5-T
e s t e r was fo u n d to p e e l o f f t h e t r e e s in l a r g e s h e e t s .

T his

c o n d itio n i s p ro b a b ly due to t h e f a c t t h a t r e l a t i v e l y l i t t l e
d i s i n t e g r a t i o n o c c u rs I n t h e phloem, w h ile c o l l a p s e i s r a t h e r
s e v e r e i n t h e cam bial r e g i o n .

T his foim s a p l a n e o f weak­

n e s s betw een cam bial r e g io n and phloem, and a llo w s th e b a rk
to be p e e le d o f f i n t a c t .

186

T reatm en t d a t e s .

T re a tm e n ts made b e f o r e l u l y 1 a r e

f a s t e r a c t i n g and more e f f e c t i v e th a n t h o s e made l a t e r i n
th e season.

A p p l i c a t i o n s made j u s t b e f o r e b u d -b reak p ro d u c e

r e s u l t s com parable to t h o s e made when l e a v e s a r e f u l l y de­
v e lo p e d .

D ate o f t r e a tm e n t a p p a r e n t l y h a s more i n f l u e n c e on

t h e r e s u l t s o f 2 ,4 ,5 - T and 2,4-D t r e a t m e n t s th a n on t h o s e
made w ith sodium m o n o c h lo r o a c e ta te .
A p p l i c a b i l i t y o f t r e a tm e n t s to commercial o p e r a t i o n s .
A lthough t r e e s t r e a t e d w ith sodium mono c h l o r o a c e t a t e and
2 , 4 ,5 - T e s t e r c o u ld be p e e l e d one y e a r a f t e r t r e a tm e n t , i t
i s f e l t t h a t t h e amount o f t i g h t b a rk re m a in in g on t h e u p p e r
s t i c k s I s too g r e a t t o w a rra n t a p p l i c a t i o n o f t h e s e m ethods
to commercial o p e r a t i o n s .

The amount o f d i s c o l o r e d wood r e ­

s u l t i n g from t r e e s s ta n d in g o v e r w i n t e r i s a ls o a d i s t i n c t
drawback to t h e e x t e n s i v e u s e o f t h e s e m ethods.
F u r t h e r I n v e s t i g a t i o n s , however, o f a p p l i c a t i o n m ethods
may e l i m i n a t e t h e s e o b j e c t i o n s and r e s u l t i n t r e a tm e n t s ap­
p l i c a b l e to commercial u s e .

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