H ISTO LO G ICAL A N D GROSS ST U D IE S OF F R U IT R U SSETING IN
TH E APPLE (M A LU S DOM E STIC A B O R K .) AS R E L A T E D TO FU N G IC ID ES
A ND F R E E Z IN G AIR T E M P E R A T U R E S

By

D A L E W ARREN KRETCHM AN

A N ABSTR AC T

S u b m itted to th e S ch o o l fo r A d v a n ced G ra d u a te S tu d ie s o f M ich ig a n
S tate U n iv e r s it y o f A g r ic u ltu r e and A p p lied S c ie n c e
in p a r tia l fu lfillm e n t o f the r e q u ir e m e n ts
fo r the d e g r e e of
DOCTOR OF PHILOSOPHY
D e p a r tm e n t o f H o r tic u ltu r e
1958

A p p roved

Ia ^

u ^ xJL lJ

L /

D A LE W ARREN KRETCHMAN

ABSTRACT

An in v e s tig a tio n w a s co n d u cted in 1956 and 1957 a t E a s t L a n sin g ,
M ic h ig a n to d e te r m in e th e p o s s ib le in t e r r e la t io n s h ip o f f r e e z in g a ir t e m p e r ­
a tu r e s o c c u r r in g n e a r b loom and th e u s e o f c e r ta in fu n g ic id e s a s a ff e c tin g
fr u it r u s s e t in g o f a p p le s (M alu s d o m e s tic a B o r k .).
In c o n tr o lle d te m p e r a tu r e e x p e r im e n ts , b e a r in g t r e e s o f the v a r i e ­
t i e s Jonathan and G o ld en D e lic io u s g r o w in g on M a ilin g VII r o o ts to c k s w e r e
e x p o s e d to, o r p r o te c te d fro m f r e e z in g a ir te m p e r a tu r e s .

The tr e e s w ere

p r u n ed to d iv id e th e b e a r in g s u r fa c e o f e a c h tr e e into tw o d is tin c t h a lv e s so
th at tw o fu n g ic id e tr e a tm e n ts c o u ld be e v a lu a te d in th e s a m e e n v ir o n m e n t.
A t h a r v e s t in 1956, it w a s found th at th e fr u it fr o m the g ly o d in
tr e a tm e n t on th e G o ld en D e lic io u s v a r ie t y fo llo w in g e x p o s u r e to f r e e z in g a ir
te m p e r a tu r e s w e r e 84. 5 p e r c e n t h e a v ily r u s s e te d , a s c o m p a r e d to 24. 4 p e r c e n t
fo r th e ca p ta n tr e a tm e n t.

T h e fr u it fro m the t r e e p r o te c te d fro m f r e e z in g a ir

te m p e r a tu r e s and r e c e iv in g the g ly o d in tr e a tm e n t w e r e 2 7 . 8 p e r c e n t h e a v ily
r u s s e t e d , w h ile the p o r tio n tr e a te d w ith ca p ta n had no fr u it so a ffe c te d .

In

1957, w h e r e g ly o d in w a s u s e d at h a lf -s tr e n g th (on e pint) p lu s o n e -fo u r th
pound o f Phygon, it w a s found that th e fr u it w e r e l e s s s e v e r e l y r u s s e t e d than
w h e r e g ly o d in w a s u s e d a lo n e at one q u a rt p e r 100 g a llo n s .
Of th e h a r v e s t e d fr u it o f th e Jonathan v a r ie t y r e c e iv in g th e g ly o d in
tr e a tm e n t in 1957 and p r o te c te d fro m e x p o s u r e to te m p e r a tu r e s b elow 32® F ,

DALE W ARREN KRETCHMAN

ABSTRACT - 2

2. 94 p e r c e n t w e r e h e a v ily r u s s e t e d and 48. 53 p e r c e n t lig h tly r u s s e t e d .

For

th o s e tr e a te d w ith ca p ta n 2. 44 p e r c e n t w e r e h e a v ily r u s s e t e d , and 19. 51 p e r ­
c e n t lig h tly r u s s e t e d .

E x p o s u r e s to m in im u m te m p e r a tu r e s o f 2 7 . 5° , 3 0 .5 ° ,

31. 5® and 30. 5®F n e a r b loom w h e r e ca p ta n w a s u se d , r e s u lt e d in 15. 52 p e r ­
c e n t o f th e fr u it h e a v ily r u s s e t e d and 46. 55 p e r c e n t lig h tly r u s s e t e d a s c o m ­
p a r e d to 67. 07 p e r c e n t h e a v ily r u s s e t e d and 28. 05 p e r c e n t o f the fr u it lig h tly
r u s s e t e d fro m the u s e o f g ly o d in .
F ie ld s tu d ie s w e r e co n d u cted at G rand R a p id s, M ich ig a n on b e a r in g
Jonathan, and M cIn to sh a p p le t r e e s c o m p a r in g fe r b a m , g ly o d in , th ira m and
ca p ta n in 1956, and w e tta b le su lfu r , g ly o d in , th ira m and ca p ta n in 1957, a s
a ff e c tin g fr u it r u s s e t in g .

In 1956, a 3 0 -m in u te p e r io d o f 30. 5*F w a s e x p e r ­

ie n c e d p r io r to b loom and no d if f e r e n c e s w e r e o b s e r v e d b e tw e en tr e a tm e n ts .
In 1957, te m p e r a tu r e s o f 31. 5®, 31. 0°“, and 31. 5®F w e r e r e c o r d e d n e a r b loom
and s ig n ific a n t d if f e r e n c e s o f h e a v ily r u s s e t e d fr u it s w e r e o b s e r v e d b e tw e en
t r e a tm e n ts on th e Jonathan v a r ie t y .

T h e t r e e s tr e a te d w ith cap tan w e r e l o ­

c a te d in th r e e d iffe r e n t a r e a s o f the p la n tin g , and th e p e r c e n ta g e o f fr u it
h e a v ily r u s s e t e d fr o m t h e s e lo c a tio n s r a n g e d fro m 12. 1 to 21. 6 p e r c e n t.
T h is c o m p a r e d to 12. 4 p e r c e n t fo r th e su lfu r tr e a tm e n t, 18. 0 p e r c e n t fo r
th e th ir a m tr e a tm e n t, and 29. 5 p e r c e n t fo r the g ly o d in tr e a tm e n t.

T he c a p ­

tan tr e a tm e n t h a v in g th e 2 1 . 6 p e r c e n t h e a v ily r u s s e t e d fr u it w a s lo w e r in

D A LE W ARREN KRETCHM AN

e le v a t io n th an th e o th e r tr e a tm e n ts .

ABSTRACT - 3

T h e e x c e s s i v e r u s s e t in g c o u ld be a s s o ­

c ia t e d w ith lo w e r a ir te m p e r a tu r e s in th e l e s s fa v o r a b le e le v a t io n .
T h e s a m e w e a th e r c o n d itio n s and s p r a y tr e a tm e n ts on M cIn to sh r e ­
s u lte d in no s ig n ific a n t d if f e r e n c e s b e tw e e n t r e a tm e n ts .

H o w e v e r , in 1957

m o r e r u s s e t in g w a s o b s e r v e d fo r a ll th e tr e a tm e n ts m a d e on both v a r i e t i e s
th an in 1956.
H is to lo g ic a l s tu d ie s w e r e c o n d u cted in 1956 to d e te r m in e th e d if f e r ­
e n c e s in d e v e lo p m e n t o f th e c u tic le and e p id e r m a l t is s u e o f th e v a r i e t i e s
G o ld en D e lic io u s , Jonathan and M cIn tosh ; and to stu d y th e d e v e lo p m e n t o f
r u s s e t e d t is s u e o f G o ld en D e lic io u s w hen c e r ta in fu n g ic id e s a r e u s e d p r io r
to s e c o n d c o v e r .
T h e f i r s t m ic r o s c o p ic s ig n s o f r u s s e t fo r m a tio n on G o ld en D e lic io u s
w e r e o b s e r v e d th r e e w e e k s a ft e r fu ll b lo o m a s a s m a ll n u m b er o f ir r e g u la r ly
p r o lif e r a t in g c e l l s o f th e o u te r c o r t ic a l la y e r .

F o u r w e e k s a ft e r fu ll b lo o m ,

t h e s e p r o lif e r a t in g c e l l s had r u p tu r ed th e e p id e r m is and c u t ic le .

A s g ro w th

o f th e fr u it c o n tin u e d , m o r e s u b - e p id e r m a l p r o lif e r a tio n o c c u r r e d and a t h a r ­
v e s t tim e , a v e r y e v id e n t p h e llo g e n w a s fo r m e d b elo w th e r u s s e t e d a r e a .

The

in itia l r u p tu r e s o f th e e p id e r m a l la y e r c o u ld n ot b e a s s o c ia t e d w ith th e p r e s ­
e n c e o f e it h e r tr ic h o m e s o r sto m a ta .

D ALE WARREN KRETCHMAN

ABSTRACT - 4

M ic r o s c o p ic s tu d ie s o f the d e v e lo p m e n t o f th e p r o t e c t iv e la y e r s o f
th e fr u it r e v e a le d that at th e tim e th e flo w e r s e m e r g e fr o m buds, the r e c e p ­
t a c le i s not c o v e r e d w ith a c u t ic le .

H o w e v er , s o m e fa tty s u b s ta n c e s w e r e

found w ith in th e e x p o s e d c e l l - w a l l s o f th e e p id e r m a l c e l l s p r io r to b lo o m .
C u tic u la r iz a tio n o c c u r r e d f i r s t a t th e b a s e s o f the tr ic h o m e s ,

T en to f o u r ­

te e n d a y s a ft e r fu ll b lo o m , th e c u tic le w a s c o m p le te on th e fr u it s u r fa c e .
T h e e p id e r m is o f M cIn to sh , Jonathan and G o ld en D e lic io u s w a s
s im ila r u n til a p p r o x im a te ly 30 d a y s a fte r fu ll b lo o m .

A t th is tim e the

e p id e r m a l c e l l s o f G o ld en D e lic io u s a p p e a r e d to s e p a r a te and s e p a r a tio n
in c r e a s e d a s the fr u it co n tin u ed to e n la r g e .
e p id e r m a l la y e r c o u ld be found.

In c o n tr a s t,

At m a tu r ity , no w e ll- d e f in e d
th e e p id e r m a l la y e r o f the

M cIn to sh r e m a in e d v e r y e v id e n t d u rin g g ro w th and m a tu r ity , and no s e p a r ­
a tio n o f e p id e r m a l c e l l s w a s o b s e r v e d .

T h e e p id e r m a l la y e r o f Jonathan,

a lth o u g h d is c e r n a b le , w a s not a s r e g u la r a s th at o f the M cIn to sh .

H ISTO LO G ICAL A N D GROSS STU D IES OF F R U IT R U SSETING IN
T H E APPLE (M A LU S D O M ESTIC A BORK. ) AS R E L A T E D TO FU N G IC ID ES
A N D F R E E Z IN G AIR T E M P E R A T U R E S

By

D A L E W ARREN K R ETC H M A N

A THESIS
S u b m itted to the S c h o o l fo r A d v a n ced G rad u ate S tu d ie s o f M ich ig a n
S tate U n iv e r s it y o f A g r ic u ltu r e and A p p lied S c ie n c e
in p a r tia l fu lfillm e n t o f the r e q u ir e m e n ts
fo r the d e g r e e o f

DOCTOR OF PHILOSOPHY

D e p a r tm e n t o f H o r tic u ltu r e

1958

P roQ uest N um ber: 10008591

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a note w ill indicate the deletion.

uest
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DEDICATED

TO MY P A R E N T S - F R E D A N D A N N K RETCH M AN

ACKNOWLEDGEMENTS

T h e au th o r w is h e s to e x p r e s s h is s in c e r e th an k s to D r. A rth u r E.
M itc h e ll, P r o f e s s o r o f H o r tic u ltu r e , fo r h is g e n e r o u s h elp , v a lu a b le s u g ­
g e s t io n s and d ir e c t io n th rou g h o u t th is in v e s tig a tio n .
G r a te fu l a c k n o w le d g e m e n t is e x p r e s s e d to D r s. H. B. T u k ey, S r . ,
A . L . K en w orth y, L . W. M e r ic le , and G. P.

S tein b a u e r fo r th e ir g e n e r ­

o u s h elp and a d v ic e in th e d e v e lo p m e n t o f th e stu d y .
e x te n d s h is s in c e r e th an k s to M r.

T he in v e s tig a to r

W a lter T o e n je s o f the M ich ig a n S tate

U n iv e r s it y G raham E x p e r im e n t Station fo r a s s is t a n c e in the u s e o f the
o r c h a r d s and eq u ip m e n t fo r th is stud y.
A n e x p r e s s io n of d eep g r a titu d e is g iv e n to th e a u th o r ’s w ife,
G le n n y c e and to h is c h ild r e n fo r th e ir e n c o u r a g e m e n t and m a n y s a c r i ­
f i c e s d u rin g the co n d u ct o f th is in v e s tig a tio n .

TABLE OF CONTENTS
P age
................................................................................

1

R E V IE W OF L I T E R A T U R E ............................................................................

4

INT R O DU C TIO N

G r o s s S tu d ie s o f F r u it R u s s e t i n g ..............................................

4

H is to lo g ic a l S tu d ie s o f F r u it R u s s e t i n g ...................................

12

M A T E R IA L S A N D M E T H O D S .......................................................................

22

E x p e r im e n t 1. C o n tr o lle d T e m p e r a tu r e S tu d ie s, 1956 .

22

E x p e r im e n t 2. F ie ld S tu d ie s, 1956

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

29

E x p e r im e n t 3. C o n tr o lle d T e m p e r a tu r e S tu d ie s, 1957 .

31

E x p e r im e n t 4. F ie ld S tu d ie s, 1957 ...........................................

34

E x p e r im e n t 5. H is to lo g ic a l I n v e s t i g a t io n s ..........................

36

R E S U L T S .................................................................................................................

41

E x p e r im e n t 1. C o n tr o lle d T e m p e r a tu r e S tu d ie s, 1956 .

41

E x p e r im e n t 2. F ie ld S tu d ie s, 1956 .............................................

47

E x p e r im e n t 3.

C o n tr o lle d T e m p e r a tu r e S tu d ie s, 1957 .

51

E x p e r im e n t 4.

F ie ld S tu d ie s, 1957 .............................................

56

I n te r a c tio n s fr o m u s e o f F u n g ic id e s and F r e e z in g A ir
T e m p e r a t u r e s on F r u it R u s s e t i n g ........................................

62

E x p e r im e n t 5. H is to lo g ic a l I n v e s tig a tio n s ..............................

71

D e v e lo p m e n t o f th e P r o te c tiv e L a y e r s o f A p p le s

. .

71

TA BLE OF C O N T EN T S - c o n t’d

P age
D e v e lo p m e n t o f R u s s e tin g o f G o ld en D e lic io u s . . . .
D IS C U S S IO N ...............................................................................................................

82
88

I n te r r e la tio n s h ip o f F r e e z in g A ir T e m p e r a tu r e s and C e r ­
ta in F u n g ic id e s on F r u it R u s s e t i n g ........................................

88

H is t o lo g ic a l S t u d i e s ................................................................................

97

S U M M A R Y ..................................................................................................................

107

L IT E R A T U R E C I T E D .........................................................................................

113

A PPENDIX A - E x p la n a tio n o f T e r m i n o l o g y ........................................

119

APPENDIX B - C h e m ic a l N a tu re o f S p ra y M a t e r i a l s .........................

122

INT R O D U C TIO N

D u r in g th e p a s t te n y e a r s , M ich ig a n a p p le g r o w e r s h a v e b een
u t iliz in g m a n y o f th e new o r g a n ic p e s t i c i d e s in v a r io u s ty p e s o f s p r a y p r o ­
g r a m s u n d er d iv e r s e c lim a t ic c o n d itio n s and h a v e e x p e r ie n c e d w id e v a r ia ­
tio n s in th e ir e f f e c t s on fr u it r u s s e t in g .
c o ld in ju r y .

T h e y a c c e p te d th e r u s s e t in g a s

M itc h e ll (35), stu d y in g th e in flu e n c e o f fu n g ic id e s on fr u it

fin is h , found th at t r e e s s p r a y e d w ith a c e r ta in fu n g ic id e p r o d u c e d fr u it w ith
a v e r y fa v o r a b le fin is h on e y e a r , w h e r e a s th e fo llo w in g y e a r , u s in g the
s a m e c h e m ic a l, th e fr u it w a s v e r y s e v e r e ly r u s s e t e d .

H o w ev er, o th e r

fu n g ic id e s in c lu d e d in th e stu d y w e r e found to c a u s e v e r y lit t le r u s s e t in g
o f th e fr u it.
D ata fro m o th e r w o r k e r s (21, 29, 43, 4 6 ) h a v e in d ic a te d th at fr u it
r u s s e t in g a ttr ib u te d to s p r a y in ju r y s e e m e d to be m o r e s e v e r e w h en " s p r in g
fr o s t s " had o c c u r r e d n e a r th e b lo s s o m in g p e r io d .

H o w e v er , no a tte m p t

w a s m ad e to c o r r e la t e th e c o m b in e d e f f e c t s o f " s p r in g fr o s t" w ith p e s t ic id e
c h e m ic a ls on th e am ou n t o f r u s s e t in g .
It w a s e v id e n t fro m p r e lim in a r y r e p o r ts (34, 35, 38) th at not a ll
v a r i e t i e s w e r e r u s s e t e d fro m th e o c c u r r e n c e o f f r e e z in g te m p e r a tu r e s c l o s e
to b loom e v e n th ough th e s a m e p e s t ic id e c h e m ic a ls w e r e u s e d .

T h is s u g ­

g e s t e d th a t a p o s s ib le d i s - s i m i l a r i t y o f th e p r o t e c t iv e l a y e r s o f th e fr u it
e x i s t s b e tw e e n s o m e v a r ie t ie s .

H is t o lo g ic a l s tu d ie s o f n o r m a l and r u s s e t e d

t i s s u e s h a v e b e e n d e s c r ib e d by e a r l i e r in v e s tig a tio n s (1, 2, 3, 4, 24, 32, 55, 57,
58, 60, 64) but th e p o s s ib le c a u s e fo r v a r ie t a l d if f e r e n c e s in s u s c e p t ib ilit y
to fr u it r u s s e t in g w a s n e g le c t e d .

H o w e v er , m e n tio n w a s m a d e o f c e r ta in

s p e c if ic v a r ie t a l c h a r a c t e r is t ic s r e la t iv e to th e o u te r t i s s u e s o f th e fr u it
(2 4 , 32, 55, 57, 6 0 ).
S in c e e a r ly fr u it r u s s e t in g i s g e n e r a lly not o b s e r v a b le w ith ou t th e
a id o f a l e n s e u n til a p p r o x im a te ly s ix w e e k s a ft e r fu ll b lo o m (6), it w a s
b e lie v e d that s p r a y c h e m ic a ls a lo n e c a u s e d th e in ju r y (21, 24, 4 3 ).

T h is

p r e m is e c o u ld a c c o u n t fo r th e o v e r s ig h t o f a p o s s ib le in te r a c tio n o f f r e e z ­
in g a ir te m p e r a tu r e s and th e u s e o f c e r ta in p e s t ic id e c h e m ic a ls a s a f f e c t ­
in g fr u it r u s s e t in g .
/

It w a s s u g g e s te d by B ell (2) th at th e a p p le flo w e r r e c e p t a c le i s not
c o m p le te ly c o v e r e d w ith a c u t ic le u n til s h o r tly a ft e r fu ll b lo o m .

B e c a u se

o f th e p r o t e c t iv e n a tu r e o f p la n t c u tic le , it s d e v e lo p m e n t m a y be r e la t e d
to fr u it r u s s e t in g .
P r e v io u s h is t o lo g ic a l in v e s tig a tio n s o f r u s s e t e d fr u it (4, 24, 29, 60)
h a v e in d ic a te d an a s s o c ia t io n w ith t r ic h o m e s and sto m a ta o f th e fr u it e p i­
d e r m is .

H o w e v e r , c a s u a l f ie ld o b s e r v a t io n s h a v e r e s u lt e d in a q u e s tio n ­

in g o f th is p r e m is e w ith r e s p e c t to f r e e z in g te m p e r a tu r e s and o r g a n ic p e s t i ­
c id e c h e m ic a ls .

3.

T h e r e fo r e , th is in v e s tig a tio n w a s u n d erta k en to d e te r m in e :
1) T h e e f f e c t s o f f r e e z in g te m p e r a tu r e s and o r g a n ic fu n g ic id e c h e m ic a ls
on fr u it r u s s e t in g and the in te r a c tin g e f f e c t s o f th e s e tw o f a c t o r s .
2) T h e r e la tio n s h ip o f c u t ic le d e v e lo p m e n t a s it m a y in flu e n c e the fa c to r s
a ff e c tin g fr u it r u s s e t in g .

3) T h e m a n n e r o f r u s s e t d e v e lo p m e n t and its

a s s o c ia t io n w ith th e t r ic h o m e s and sto m a ta o f th e fr u it e p id e r m is .
4) T h e p o s s ib le r e a s o n fo r v a r ie t a l d if fe r e n c e s o f r u s s e t s u s c e p tib ilit y .

R E V IE W OF L IT E R A T U R E

" F r o s t ” h a s lo n g b e e n c o n s id e r e d a p r im a r y c a u s e o f fr u it
r u s s e t in g o f a p p le s .

O ne o f th e e a r l i e s t r e c o r d in g s o f th is p r e m is e w a s

m a d e by D o r s e y (9) in 1 9 1 8 .

R e fe r r in g to th e c o n d itio n o f th e a p p le a w e e k

a ft e r b e in g e x p o s e d to a te m p e r a tu r e o f 27° F o c c u r in g a t fu ll b l o o m i / ,
h e s a id "T he p i s t i l s , s e e d s , and c o r e w e r e b r o w n --th a t i s k ille d - - a n d th e
sk in s e p a r a t e d fr o m the you n g a p p le in p a tc h e s o r e n t ir e ly .
s o m e v a r ia tio n s fou n d in th e d e g r e e o f k illin g .

T here w ere

In s o m e c a s e s th e p i s t i l s

w e r e not k ille d an d in o th e r s th e s e e d s w e r e not.

In a ll c a s e s w h e r e th e

p is t il , s e e d s , and c o r e w e r e k ille d , th e a p p le f e ll a few d a y s a fte r w a r d .
W h e r e t h e s e w e r e n ot k ille d , and th e sk in o n ly w a s a ffe c te d by b e in g b ro k en
a w ay, t h e s e a p p le s ‘set* and m a tu r e d .

T h e sk in b e in g k ille d e n t ir e ly or

o n ly p a r t w a y aro u n d so o n d r ie d and tu rn ed brow n, and w ith fu r th e r g ro w th
o f th e a p p le, w a s to r n aw ay, le a v in g th e s u r fa c e u n d ern ea th e x p o s e d . It
w a s now n e c e s s a r y to fo r m a new s u r fa c e to t h is a r e a le ft b a r e by th e r e ­
m o v a l o f th e sk in o r e p id e r m is . "
S im ila r c o n d itio n s w e r e r e p o r te d by M a c D a n ie ls and H e in ic k e (29)
and by R o s e n (53) fo llo w in g f r e e z in g te m p e r a tu r e s o c c u r in g n e a r b lo o m .

y S e e A p p en d ix A

fo r an e x p la n a tio n o f te r m in o lo g y .

T h e ty p e o f fr u it r u s s e t in g o c c u r in g fr o m c o ld in ju r y o f th is n a tu re d e s c r ib e d
by m an y a u th o r s (1, 9, 10, 11, 14, 15, 16, 20, 24, 29, 55), m ig h t b e s t be i l l u s ­
tr a te d by th e w o r d s o f H e d r ic k (24), " F r o s t r u s s e t in g on fr u it n e a r ly a lw a y s
a p p e a r s in b an d s o r z o n e s o f g r e a t e r o r l e s s w id th ru n n in g a ro u n d th e fr u it
m id w a y b e tw e e n b a s e and a p ex " .

O th er k in d s o f r u s s e t p a tte r n s w e r e r e ­

p o r te d by G o u rley _ et al_. (20), " F r o s t in ju r y m a y ta k e th e fo r m o f r u s s e t in g
th e fr u it, o c c u r in g e it h e r in b an ds, in p a tc h e s about the b a sin o r c a v ity ,
o r in s p o ts on th e s u r fa c e o f th e sk in " .

T h is la tte r ty p e o f r u s s e t in g h a s

u s u a lly b e e n a s s o c ia t e d w ith m ild e r f r e e z in g te m p e r a tu r e s .
C old in ju ry , s e v e r e en ough to c a u s e bands of r u s s e t e d t is s u e
on th e fr u it a s d e s c r ib e d by H e d r ic k (24) w a s not n e c e s s a r i l y r e la t e d to
th e u s e o f s p r a y c h e m ic a ls b e c a u s e it w a s o b s e r v e d in o r c h a r d s fo llo w in g
f r e e z in g te m p e r a tu r e s c l o s e to b lo o m that r e c e iv e d no s p r a y s d u rin g th e
g r o w in g s e a s o n (29).

W hen f r e e z in g te m p e r a tu r e s o c c u r r e d c l o s e to

b lo o m , M a c D a n ie ls and H e in ic k e (29) p o s tu la te d th at an e x p la n a tio n fo r
the o c c u r r e n c e o f th e r u s s e t in g in a r a th e r lo c a liz e d m a n n e r on s o m e fr u it
and d iffu s e d o v e r th e fr u it on o th e r s m ig h t be due to a s lig h t d iffe r e n c e in
th e te m p e r a tu r e w h ic h k ille d the c e l l s o f the e p id e r m is and a d ja ce n t
tis s u e s .

A ir m o v e m e n t c o u ld in flu e n c e th is v a r ia tio n in te m p e r a tu r e .

T h e y a ls o s ta te d , "W here th e f r e e z e o c c u r s b e fo r e th e f lo w e r s o f the
b lo s s o m in g c lu s t e r s s e p a r a te , th e in ju r y h a s b een o b s e r v e d to be c o n fin ed

to th e d e fin ite s e c t o r s o f th e fr u it, to u c h in g e a c h o th e r a t th a t tim e .

C on­

ta c t o f th e y o u n g o v a r ie s o f th e b lo s s o m s w ith e a c h o th e r o r a d ja c e n t le a v e s
m a y a ls o h a v e s o m e th in g to do w ith th e f r o s t r in g s th a t a r e fr e q u e n tly
fo r m e d " .
F o r m a n y y e a r s th e c o p p e r fu n g ic id e s , b o r d e a u x and fix e d
c o p p e r , lim e - s u l f u r m ix t u r e s and la t e r e le m e n ta l su lfu r w e r e th e p r in c i­
p a l fu n g ic id e s u s e d on a p p le t r e e s (M a lu s d o m e s tic a B o r k .) in th is co u n try .
T h e r e p o r t s o f in ju r y to th e f in is h o f the fr u it d u rin g th is p e r io d a r e q u ite
n u m e r o u s (1, 11, 15, 18, 24, 43, 47, 51, 52, 6 3 ).

D utton (11) h a s sta te d , "T he

r u s s e t in g o f th e fr u it, fo llo w in g th e u s e o f b o r d e a u x in e a r ly s u m m e r a p p li­
c a tio n s , i s a lim it in g fa c to r in th e u s e o f th is s p r a y on a p p le s " .
M o r s e (43), u s in g liq u id lim e - s u l f u r a s th e fu n g ic id e and le a d
a r s e n a t e a s an in s e c t ic id e , r e p o r te d a h ig h e r p e r c e n ta g e o f r u s s e t in g in
th e s p r a y e d p lo t s than in the u n sp r a y e d p lo t s .

B aker (1) n o ted th at " s u l­

fu r burning" o c c u r r e d la te in th e s e a s o n d u rin g hot w e a th e r and g e n e r a lly
r e s u lt e d in r u s s e t in g o f the fr u it.

T h e s e a u th o r s (1, 43) a s s o c ia t e d a b lo tch y

o r " n e t-lik e " r u s s e t in g w ith s p r a y in ju r y .

T h is i s q u ite d iffe r e n t than th e

" r u s s e t r in g s " o r s t r e a k s d e s c r ib e d e a r l i e r (24) a s c h a r a c t e r is t ic o f f r o s t
in ju r y .

It sh o u ld be n o ted a ls o fr o m th e s e e a r li e r r e p o r t s on fr u it fin is h ,

th at f r o s t w a s p r o b a b ly r e la t e d to th e s e v e r it y o f r u s s e t in g , a lth o u g h not

7.

r e c o g n iz e d a s a fa c to r .

F o r e x a m p le , M o r s e (43) o b s e r v e d th at d u rin g

th e y e a r w hen th e s p r in g w a s w et, c o ld and " fr o s ty ”, m o r e r u s s e t in g w a s
n o ted at h a r v e s t than in the fo llo w in g y e a r u s in g th e s a m e sp r a y c h e m ic a ls
w h en m o r e fa v o r a b le w e a th e r c o n d itio n s o c c u r r e d in th e s p r in g .
H a m ilto n and P a lm ite r (21) o b s e r v e d that th e fr u it fro m a lo w e r
e le v a t io n o f a b lo c k o f G o ld en D e lic io u s had m o r e r u s s e t in g than fr u it fro m
the h ig h e r p o r tio n o f th e p la n tin g .

T h is , th ey sta te d , in d ic a te d that a ir

d r a in a g e is a fa c to r in r u s s e t in ju r y .

T h e s e a u th o r s w e r e in t e r e s t e d in

a ir d r a in a g e a s it in flu e n c e d d r y in g c o n d itio n s r a th e r than the p o s s ib le
a s s o c ia t io n o f f r e e z in g te m p e r a tu r e and r u s s e t in g at th e s e lo w e r e le v a t io n s .
S in c e th e in tr o d u c tio n o f fe r b a m i^ in 1939 (19, 25), m an y o r g a n ic
fu n g ic id e s h a v e b een found w h ich h a v e l e s s u n fa v o r a b le p h y s io lo g ic a l e f f e c t s
o n a p p le t r e e s and fr u it s than th e e a r li e r c o n v e n tio n a l c h e m ic a ls .

M any

o f th e s e m a t e r ia ls h a v e had w id e - s p r e a d u s e in c o m m e r c ia l a p p le o r c h a r d s
w ith v a r y in g r e s u l t s .

P a lm ite r (4 6 ) r e p o r te d th at l e s s fr u it w e r e r u s s e t e d

fr o m th e u s e o f fe r b a m w ith le a d a r s e n a t e than w e tta b le su lfu r and le a d
a r se n a te.

He a ls o o b s e r v e d m o r e r u s s e t in g on G o ld en D e lic io u s w ith the

u s e o f fe r b a m than on R ed D e lic io u s .

G a rm a n (17, 18) found s im ila r r e ­

s u lt s w ith th e s a m e m a t e r ia ls on o th e r v a r ie t ie s of a p p le s .
1/
— S e e A p p en d ix B fo r th e c h e m ic a l n a tu re o f th e s p r a y co m p o u n d s.

S h a r v e lle (54) n o te d th at th e u s e o f ca p ta n p r o d u c e d a h ig h e r p r o ­
p o r tio n o f r u s s e t - f r e e fr u it th an w h en b o rd ea u x , w e tta b le s u lfu r o r ferb a m
w e r e u s e d in th e s p r a y p r o g r a m on G old en D e lic io u s .
A s ta te m e n t m a d e by M itc h e ll (33) in 1951 i s o f in t e r e s t , "W ith
th e w e a th e r in fo r m a tio n now a v a ila b le , g r o w e r s ca n a v o id a c e r ta in a m o u n t
o f r u s s e t in g by u s in g s p r a y c h e m ic a ls a p p r o p r ia te to th e w e a th e r c o n d itio n s .
D u r in g s o m e s e a s o n s a lm o s t any o f the sp r a y c h e m ic a ls m a y be u s e d w ith
lit t le e f f e c t on fin is h .

It i s th e o c c a s io n a l y e a r that s e le c t io n o f sp r a y

c h e m ic a ls i s so im p o rta n t" .

T h e o c c a s io n a l y e a r he r e f e r s to i s o n e in

w h ic h f r e e z in g te m p e r a tu r e s o c c u r c l o s e to b lo o m .

T h is p r e m is e i s th e

f ir s t in d ic a tio n s in c e th e in tr o d u c tio n o f o r g a n ic p e s t ic id e c h e m ic a ls , that
w e a th e r c o n d itio n s a r e p la y in g a r o le in th e e f f e c t s o f c e r ta in o f th e s e new
fu n g ic id e s on fr u it r u s s e t in g .
S in c e t h is e a r ly g e n e r a liz a tio n , M itc h e ll (36, 37, 38, 39) h a s r e ­
p o r te d fu r th e r o b s e r v a t io n s on fr u it r u s s e t in g s u p p o se d ly c a u s e d b y fu n g i­
c id e c h e m ic a ls c l o s e l y r e la t e d to f r e e z in g te m p e r a tu r e s n e a r fu ll b lo o m .
H e s ta te d (36), "No s p r a y c h e m ic a l c a n be e x p e c te d to s u b s titu te fo r lo c a ­
tio n and w e a th e r c o n d itio n s w h en t h e s e tw o f a c to r s m a y be th e r e a s o n fo r
fr u it r u s s e t in g .

F o r e x a m p le , in 1 9 5 3 .ca p ta n w a s u s e d on b e a r in g G o ld en

D e lic io u s t r e e s in tw o lo c a tio n s o f th e M ich ig a n S ta te U n iv e r s it y H o r tic u ltu r a l

9.

fa r m , E a s t L ansing*
e a c h b lo c k o f tr e e s *

T h e s a m e s p r a y m ix t u r e s o f ca p ta n w e r e u s e d on
H o w e v e r , at h a r v e s t tim e th e fr u it s fr o m on e lo c a tio n

w e r e s e v e r e ly r u s s e t e d w h ile th e f in is h o f fr u it s fro m th e s e c o n d lo c a tio n
w a s e x c e lle n t .
b lo o m .

C old, h u m id c o n d itio n s e x is t e d on o r about th e tim e o f fu ll

T h is c o n d itio n , c o u p le d w ith th e la c k o f a ir d r a in a g e in one lo c a ­

tio n , r e s u lt e d in s e v e r e fr u it r u s s e t in g o f th e G o ld en D e lic io u s .

N ever­

t h e le s s , the fr u it o f M cIn to sh , C o rtla n d , N o r th e r n Spy and W ea lth y g ro w n
in th is s a m e lo c a tio n had v e r y good fin is h .

T h u s,

it i s c le a r that under

c e r t a in e n v ir o n m e n ta l c o n d itio n s fr u it r u s s e t in g o f s o m e v a r i e t ie s w ill
o c c u r r e g a r d le s s o f s p r a y c h e m ic a l u se d " .
M itc h e ll h a s r e p o r te d that g ly o d in h a s c a u s e d r u s s e t in g o f G o ld en
D e lic io u s (3 7 ).

H e a ls o o b s e r v e d the in c r e a s e d in c id e n c e o f r u s s e t in g on

Jonathan fro m th e u s e o f fe r b a m (38) w hen a low o f 29" F o c c u r r e d a t th e
tim e o f p in k and a low o f 31° F at fu ll b lo o m .

T h is s a m e m a t e r ia l, h o w ­

e v e r , r e d u c e d th e am ou n t o f r u s s e t in g on R ed D e lic io u s and M cIn to sh w hen
c o m p a r e d to th e u s e o f w e tta b le su lfu r .

He n o ted in y e a r s w hen th e a ir

te m p e r a tu r e r e m a in e d a b o v e 3 3 ° F , th e r e w a s v e r y lit t le d iffe r e n c e in th e
fr u it f in is h o f t h e s e th r e e v a r ie t ie s r e s u lt in g fro m th e tr e a tm e n ts , w e tta b le
s u lfu r v e r s u s fe r b a m .
I n v e s tig a tio n s on fr u it f in is h o f th e B a rtlett p e a r by H a r r is and

G r ig g s (22, 23) r e v e a le d r u s s e t e d fr u it in lo c a tio n s th at had e x p e r ie n c e d
f r e e z in g te m p e r a tu r e s n e a r b lo o m .

In a r e a s that did not h a v e th e s e c o ld

te m p e r a tu r e s , v e r y l i t t l e r u s s e t in g w a s o b s e r v e d .
H e d r ic k (24) s u g g e s te d in 1907 that th e am ou n t o f in ju r y fro m
b o r d e a u x s p r a y s v a r ie d g r e a t ly w ith: (1) T h e s tr u c tu r e o f the sk in due to
th e g r e a t v a r ia tio n s in th e s k in s o f a p p le s o f d iffe r e n t v a r i e t i e s .

(2) T h e

c o n d itio n o f th e sk in a s to th e a g e o f fr u it and th e s u c c u le n c y o r te n d e r n e s s
fr o m w e a th e r c o n d itio n s .

He o b s e r v e d that fro m fo u r to s ix w e e k s a fte r

b lo s s o m s drop, the you n g a p p le w a s c o v e r e d w ith a fe lt o f fin e h a ir s .

He

s ta te d , " E x a m in ed u n d er th e m ic r o s c o p e , o n e s e e s upon the e p id e r m is o f
th e y o u n g a p p le m a n y sto m a ta .

In tim e th e h a ir s and m o s t o f th e sto m a ta

a r e lo s t , th e fo r m e r d ro p p in g off, le a v in g a d is tin c t s c a r " .

H e d r ic k

e x p la in e d th at b o r d e a u x p r o b a b ly c a u s e d in ju r y to th e s e h a ir s and a d ja c e n t
e p id e r m a l c e l l s a s w e ll a s to c e l l s a d ja ce n t to th e sto m a ta .

T he r e s u lt

b e in g th at th e s e c e l l s w e r e u n ab le to, in h is w o r d s, " b ea r th e ir sh a r e o f
th e s u r fa c e te n sio n " a s the fr u it g r o w s , c a u s in g a te a r in th e sk in o f the
fr u it.

H e fu r th e r s ta te d , "It i s th e d ea d c e l l s and the h e a lin g o f th e s e la c e r

a tio n s , th e c ic a t r iz a t io n o f w ou n d s, th at c a u s e s th e c o rk y , r u s s e t e d la y e r
on f r u it s w h ic h w e c a ll b o r d e a u x in ju ry " .

He m a d e a n o th e r im p o rta n t o b s e r

v a tio n that b o r d e a u x in ju r y p r o b a b ly d o e s not o c c u r a ft e r th e h a ir s a r e sh ed ,

o r w hen th e s to m a ta h a v e c h a n g e d to le n t i c e l s and a fte r a w a x y c o a tin g
is fo r m e d .
M o r s e (43) o b s e r v e d in 1916, th at w hen the p in k -s ta g e s p r a y o f
liq u id lim e - s u l f u r and le a d a r s e n a t e w a s o m itte d , n e a r ly 13. 5 p e r c e n t
m o r e m e r c h a n ta b le a p p le s w e r e o b ta in ed due to a g r e a t e r fr e e d o m o f
r u s s e t in g .
M o re r e c e n t s tu d ie s by P a lm ite r (46) and by M itc h e ll (33, 36, 37,
38, 39) h a v e in d ic a te d that the c r it ic a l p e r io d o f fr u it d e v e lo p m e n t w hen
in ju r y m a y o c c u r is fro m p r e -p in k to a p p r o x im a te ly tw o w e e k s a fte r fu ll
b lo o m .
T h is c o u ld be r e la t e d to th e typ e o f flo w e r and fr u it o f th e a p p le .
B lack (5) d e s c r ib e d the a p p le a s a r e - e n f o r c e d o r c o m p o s ite fr u it c o n s i s t ­
in g o f o n e to s e v e r a l d r u p e -lik e fr u its em b ed d ed in a fle s h y to r u s and i s
c a lle d a p o m e .

T h e to r u s is th e r e c e p t a c le o f an e p ig y n o u s flo w e r and by

e x c e s s i v e grow th p r o d u c e s the m a jo r fle s h y or e d ib le p o r tio n o f the fr u it.
By th is d e s c r ip t io n o f an e p ig y n o u s flo w e r , it m a y be a s s u m e d
th a t a s so o n a s th e r e c e p t a c le o f th e flo w e r i s e x p o s e d to e x te r n a l c o n d i­
tio n s, a n y e n v ir o n m e n ta l fa c to r s a ff e c tin g th e flo w e r w ill su b se q u e n tly
a ff e c t th e a p p e a r a n c e o f th e r e s u lt in g fr u it.

12.

H is to lo g ic a l S tu d ie s

B ell (2) h a s d iv id e d th e p r o t e c t iv e l a y e r s o f th e a p p le into fo u r
r e g io n s : (a) c o a tin g o f e p id e r m a l h a ir s ; (b) th e c u tic le ; (c) the e p id e r m is ;
and (d) th e h y p o d e r m is .

H e o b s e r v e d th at a t th e tim e th e f lo w e r s e m e r g e

fr o m th e w in te r bu ds, th e flo w e r r e c e p t a c le w a s c o v e r e d w ith a th ic k
c o a tin g o f h a ir s .

T h r e e w e e k s b e fo r e fu ll b lo o m c u t ic le s ta r te d to fo rm

at th e b a s e o f th e h a ir s and by abou t th ir ty d a y s a fte r fu ll b lo o m , it had
c o m p le t e ly f ille d in a ro u n d the b a s e and g e n e r a lly an y m o v e m e n t w o u ld c a u s e
th e h a ir to b r e a k off.

C o n c e r n in g th e c u tic le , B ell sta te d , ”A t th e tim e th e

flo w e r e m e r g e s th e c u t ic le i s h ard to d e fin e, but by u s in g Sudan IV, it c a n
be s e e n a s p a tch y on th e s u r fa c e and by th e end o f th e s e c o n d w e e k a fte r
fu ll b lo o m , th e c u t ic le i s c o m p le te e x c e p t fo r s to m a ta o r youn g le n t i c e l s
w h e r e it s h a d e s o ff to n oth in g.

D u r in g A u g u st th e c u tic le s t a r t s to in v a d e

th e e p id e r m a l and in s o m e c a s e s e v e n the h y p o d e rm a l la y e r o f c e l l s and
it i s d iffic u lt to m e a s u r e it s th ic k n e s s " .

H e a p p r o x im a te d it s th ic k n e s s to

be about 23 m ic r o n s .
T u k ey and Y ou n g (59) r e p o r te d th at the c u tic le a p p e a r s in c r o s s s e c t io n a s s c a r c e l y m o r e than a lin e a t fu ll b lo o m .

M e y e r (32), u s in g Sudan

III a s a s p e c if ic s ta in fo r fa tty m a t e r ia ls (27), n o ted that th e o u te r ta n g e n tia l
w a lls o f th e e p id e r m a l c e l l s to o k a s m a ll am ou n t o f Sudan III in d ic a tin g a

d e p o s itio n o f w a x y m a t e r ia ls .

H e a ls o o b s e r v e d a s lig h t in c r e a s e in the

c u t ic le w h ic h o c c u r r e d fr o m fu ll b lo o m on w ard , p a r t ic u la r ly a ro u n d th e
h a ir b a s e s .

H o w e v e r , h e s ta te d that th e c u tic le w a s not d is tin c t and

m e a s u r a b le on G o ld en D e lic io u s u n til a p p r o x im a te ly e ig h te e n d a y s fo llo w ­
in g fu ll b lo o m a ft e r w h ic h it in c r e a s e d in th ic k n e s s to 13. 18 m ic r o n s .
P r ie s t ly (50), w ho w o r k e d on s t e m s o f a n g io s p e r m p la n ts s ta te d ,
" F ro m th e o u ts e t th e e s s e n t ia l f i r s t s ta g e o f a c u t ic le i s p r e s e n t o v e r the
a p e x a s a c o n tin u o u s la y e r o f fa tty s u b s ta n c e s o v e r ly in g th e c e ll u lo s e w a lls
o f th e o u t e r m o s t c e ll s " .

H e in d ic a te d that p la n t t i s s u e s e x p o s e d to the

a tm o s p h e r e w e r e c o v e r e d w ith a co n tin u o u s film o f o il o r fa t th a t c o u ld be
te r m e d c u t ic le .

E sa u (13) p r e s e n t e d a s im ila r d e s c r ip t io n o f th e c u tic le

c o a tin g o f e x p o s e d p la n t t i s s u e .

T h e s e g e n e r a liz a t io n s a r e in d is tin c t c o n tr a s t

w ith o b s e r v a t io n s (2, 32, 59) m a d e on a p p le fr u it d e v e lo p m e n t.

F u r th e r m o r e ,

W h a ley , M e r ic le and H e im is c h (62) and M e r ic le and W h aley (31) r e p o r te d
th a t in th e m e r is t e m a t ic a p e x o f th e sh o o t o f c o r n (Z e a m a y s L . ) th e y c o u ld
fin d no p o s it iv e in d ic a tio n o f th e p r e s e n c e o f fa ts in the w a lls o f th e m e r i ­
s t e m a t ic c e l l s .

T h e s e r e p o r t s o f v a r ie d o b s e r v a t io n s s t i l l le a v e r o o m fo r

d eb a te on c u t ic le d e v e lo p m e n t o f a p p le f r u it s .
T h e e p id e r m is o f M cIn to sh and T w en ty O unce a s stu d ie d by T u k ey
and Y o u n g (59) w a s d e s c r ib e d a s a u n is e r ia t e la y e r o f p a li s a d e - l ik e c e l l s

w h ic h c o u ld be id e n tifie d e v e n o n e m o n th b e fo r e fu ll b lo o m .

T h ey o b s e r v e d

th e c e l l s to be e lo n g a te d r a d ia lly u n til fu ll b lo o m w hen th e c e l l s b eg a n a
ta n g e n tia l e lo n g a tio n w h ic h c o n tin u e d u n til m a tu r ity .

T h ey found that d iv i­

s io n o f e p id e r m a l c e l l s c o n tin u e d u n til e v e n 85 d a y s a ft e r fu ll b lo o m .
A c c o r d in g to B ell (2) c e l l d iv is io n c e a s e s in th e v a r ie t y M cIn to sh
in N ova S c o tia d u rin g th e m id d le o f June w h en fu ll b lo o m w a s June 2.

T e t le y

(58) r e p o r te d d iv is io n in B r a m le y S e e d lin g on June 12 in m a t e r ia l c o lle c t e d
n e a r C a m b r id g e , E n glan d .

T he fin d in g s o f B ell (2) and T e t le y (58) w e r e

b a s e d on o b s e r v a t io n o f m it o tic d iv is io n s , w h e r e a s T u k e y and Y oun g (59)
m a d e c o u n ts o f n u m b e r s o f e p id e r m a l c e l l s a t v a r io u s s t a g e s o f d e v e lo p ­
m e n t.
R e p o r ts r e la t in g to th e c e l l s tr u c tu r e o f the e p id e r m is g iv e th e
in d ic a tio n th at in c e r ta in v a r ie t ie s , the e p id e r m is m a y r e m a in in ta c t u n til
m a tu r ity , w h ile o th e r v a r i e t i e s m a y h a v e the e p id e r m is in te r r u p te d by the
c u t ic le .

In the la tt e r c a s e , in d iv id u a l c e l l s o r g r o u p s o f c e l l s o f the e p i ­

d e r m is m a y be c o m p le te ly su r r o u n d e d by c u t ic le .

T h e r e m a y a ls o be

in t e r c e d in g v a r ia tio n s b e tw e e n t h e s e tw o e x t r e m e s .
M e y e r (32), stu d y in g the G o ld en D e lic io u s , o b s e r v e d that one
m o n th a ft e r fu ll b loom th e e p id e r m is b e c a m e ir r e g u la r ly in te r r u p te d by
c u t ic le w h ic h w a s d is t in c t ly d iffe r e n t fr o m th e r e g u la r e p id e r m is o f th e

W in e sa p v a r ie t y a t t h is s ta g e .

V e r n e r (60) s ta te d , "In a ll v a r i e t i e s e x a m ­

in ed , th e c e l l s o f th e e p id e r m is had p u lle d a p a r t in to s m a ll g r o u p s and
th e e p id e r m is had r e m a in e d in ta c t o n ly by v ir tu e o f in c r e a s e in th e c u tic le ,
w h ic h h ad b e e n p r o je c te d in to th e i n t e r s t i c e s fo r m e d b e tw e e n th e r a d ia l
w a lls o f th e c e l l s th at had b e e n s e p a r a te d .

In m a n y c a s e s , c e l l s o f th e

e p id e r m is w e r e c o m p le te ly im b e d d e d in c u tin and o b v io u s ly w e r e in c a p a b le
o f fu r th e r g r o w th .

T h e d e v e lo p m e n t o f th is c o n d itio n o f th e e p id e r m is

p r o b a b ly i s a ttr ib u te d to p r e m a tu r e c e s s a t io n o f d iv is io n and g r o w th in the
c e i l s o f th is la y e r , w ith a su b se q u e n t s e p a r a tio n o f th e s e c e l l s a s th e
fr u it e n la r g e s " .

T h e s e o b s e r v a t io n s w e r e m a d e on m a tu r e fr u it.

H e d r ic k

(24) and T e t le y (57, 58) n o ted s im il a r c o n d itio n s .
W ork by S im o n s (55) r e v e a le d th at th e e p id e r m is o f G o ld en D e l i ­
c io u s on S e p te m b e r 10 in I llin o is w a s v e r y ir r e g u la r and that th e c u t ic le
e x te n d e d d e e p ly in to th e e p id e r m a l and h y p o d e r m a l la y e r s .

On th e Jonathan

v a r ie t y a t th e s a m e d ate and in th e s a m e lo c a tio n , he o b s e r v e d a c o n tin u o u s
la y e r o f u n in te r r u p te d c e l l s in th e e p id e r m is , and th e s u b - e p id e r m a l c o r t ic a l
c e l l s w e r e m u ch m o r e o r d e r ly a r r a n g e d than in th e G old en D e lic io u s .

He

r e p o r te d th e a v e r a g e c u t ic le th ic k n e s s a t th is d ate a s 10. 0 m ic r o n s fo r
Jonathan and 2 4 . 3 m ic r o n s fo r G o ld en D e lic io u s .
T h e fo u rth and fin a l r e g io n in th e p r o te c tiv e la y e r s c o n s id e r e d

b y B ell (2) i s th e " h y p o d e r m is" .

T u k e y and Y o u n g (59) d e s c r ib e the h y p o -

d e r m a l la y e r a s fo llo w s : " T h e h y p o d e r m a l la y e r i s p a r t o f th e c o r t e x i m ­
m e d ia t e ly b e n e a th th e o u te r e p id e r m is , c h a r a c t e r iz e d in th e m a tu r e fr u it
by th ic k - w a lle d c o lle n c h y m a in w h ich th e p r o to p la s t ic c o n te n ts h a v e b e ­
c o m e g r a n u la r in n a tu r e and a r e l e s s d e n s e ly p ig m e n te d .
th e e p id e r m is it f o r m s the sk in o f th e fr u it" .

T o g e th e r w ith

T h e a u th o r s (59) o b s e r v e d

c e l l w a lls o f th e o u te r c o r t ic a l c e l l s o n e o r tw o c e l l - l a y e r s b elo w the
e p id e r m is a s b e c o m in g th ic k e n e d by fu ll b loom w ith th is th ic k e n in g in ­
c r e a s in g a s th e fr u it d e v e lo p s .

F u r th e r m o r e , th e y s ta te th at t h e s e c e l l s

a r e s m a ll and e a s i l y d e fin e d but the n u m b e r s o f c e l l - l a y e r s in th ic k n e s s
i s not e a s i l y d e te r m in e d .

B ell (2) a ls o had d iffic u lty in d e te r m in in g the

n u m b e r s o f c e l l la y e r s in th e h y p o d e r m is due to th e n o ted ir r e g u la r it y .
V a r io u s h is t o lo g ic a l d e s c r ip t io n s o f r u s s e t e d t is s u e and it s
d e v e lo p m e n t h a v e b e e n a d v a n ce d .

Z sc h o k k e (64) w a s th e f i r s t to e x a m in e

m ic r o s c o p ic a lly , c o r k fo r m a tio n on a p p le f r u it s .

A lth ou gh h is w o r k w a s

p r im a r ily c o n c e r n e d w ith le n t ic e l fo r m a tio n , he did o b s e r v e th at th e f o r ­
m a tio n of c o r k on th e n o r m a lly r u s s e t e d v a r ie t i e s o f a p p le s s ta r te d about
s ix to e ig h t w e e k s a ft e r flo w e r in g .

He c o m m e n te d on th e p r e s e n c e of

e p id e r m a l h a ir s and in s o m e in s ta n c e s c o r k fo r m a tio n w a s o b s e r v e d a t
th e b a s e s o f th e h a ir s .

T h is he c l a s s i f i e d a s a typ e o f le n t ic e l fo r m a tio n

17.

but t h e s e le n t i c e ls w e r e not lik e ty p ic a l le n t i c e ls .

N e v e r t h e le s s , he

c o n s id e r e d th at th e y w e r e fu n c tio n a lly c o m p a r a b le .

T y p ic a l le n t ic e ls ,

a s o b s e r v e d by Z sc h o k k e (64), w e r e c o n s id e r e d to o r ig in a te fro m n u m e r ­
o u s s to m a ta on th e s u r fa c e o f a you n g a p p le fr u it and w h ich b e c a m e s e a le d
by th e su b se q u e n t fo r m a tio n o f c o r k b elo w th e s to m a ta l o r if ic e .
H e d r ic k (24) e x a m in e d r u s s e t e d t is s u e c a u s e d by b o rd ea u x in ­
ju r y .

H e o b s e r v e d th at e a r ly r u s s e t in g u s u a lly s ta r te d a t the b a s a l c e l l s

o f th e tr ic h o m e s (e p id e r m a l h a ir s ) w h ich c o v e r the y o u n g fr u it o r at the
s to m a ta w h ich a r e in t e r s p e r s e d b e tw e e n th e h a ir s .

He p o s tu la te d that

th e t r ic h o m e s , th rou gh s o m e p e c u lia r it y o f s tr u c tu r e , p e r m it th e e n tr a n c e
o f th e to x ic s u b s ta n c e o f th e b o rd ea u x m ix tu r e to a g r e a t e r e x te n t than do
o th e r c e l l s w h ile the s to m a ta g iv e an a lm o s t u n o b str u c te d e n tr a n c e .
H e d r ic k (24), lik e Z sc h o k k e (64), o b s e r v e d the in ju ry on th e fr u it a p p r o x ­
im a t e ly s ix w e e k s a ft e r p e ta l fa ll.

H e d r ic k (24) a ls o found the c u tic le

p r o p e r and m a n y o f the c e l l s o f th e e p id e r m a l la y e r d e s tr o y e d and it a p p e a r e d
to him that th e to x ic s u b s ta n c e e n te r e d th e c e l l s t h e m s e lv e s and e ffe c te d
o n ly th o s e in w h ich th e to x ic com p ou n d e n te r e d .

H e c o n c lu d e d th at c o r k

fo r m a tio n o r r u s s e t in g w a s a h e a lin g p r o c e s s below th e s e in ju r ed c e l l s
s im ila r to r u s s e t in g w h ic h o c c u r s w hen a fr u it is rubbed a g a in s t a b ra n ch .
T h e d iffu s e d typ e o f r u s s e t in g found on th e G r im e s a p p le by
B aker (1) w a s a ttr ib u te d to p o s s ib le sp r a y in ju ry , high a tm o s p h e r ic h u m id ity ,

18.

c o o l w e a th e r at b lo s s o m in g tim e , f r o s t in ju ry , s u lfu r - d io x id e in the a ir
o r a c o m b in a tio n o f t h e s e f a c t o r s .

H e d e s c r ib e d r u s s e t fo r m a tio n a s

d e v e lo p in g w h en th e e p id e r m is o r th e c u t ic le i s in ju r ed w ith th e m a tu r e
c e l l s im m e d ia te ly b elo w th e e p id e r m is (h y p o d e r m a l c e l l s ) r e v e r t in g to
m e r is t e m a t ic a c tiv ity .

T h is is fo llo w e d by th e fo r m a tio n o f a p h e llo g e n

o r c o r k c a m b iu m w h ich su b s e q u e n tly g iv e s r i s e to th e r u s s e t e d o r c o r k y
area.
H is t o lo g ic a l s tu d ie s o f c o r k fo r m a tio n w e r e m a d e a ls o by
T e t le y (57) in E n glan d .

She, too, o b s e r v e d c o r k fo r m a tio n b eg in n in g at

th e b a s e o f th e t r ic h o m e s in the s u b -e p id e r m a l c e l l s .

She fe lt th at th e

h a ir b a s e s e v id e n tly r e p r e s e n te d w e a k p la c e s on th e s u r fa c e o f the a p p le
f o r any c r a c k in th e sk in n e a r ly a lw a y s b eg a n in th is r e g io n .

H o w ev er,

s h e n o ted u n d er c e r ta in w e a th e r c o n d itio n s c r a c k s o c c u r r e d w ith no
s p e c ia l r e f e r e n c e to l e n t i c e ls o r b a s e s o f h a ir s .

T h e s e c o n d itio n s, sh e

r e p o r te d , w e r e a s s o c ia t e d w ith a lo n g dry, c o ld p e r io d w hen th e fr u it w a s
s e t t in g w h ich w a s fo llo w e d by a w a r m , r a in y p e r io d w hen the a p p le w a s
r e a d y to s w e ll.

T h is c o ld p e r io d , a c c o r d in g to T e t le y (57), p r o d u c e d a

c o m p a r a tiv e ly th ic k and u n e la s tic typ e o f c u tic le w ith th e r e s u lt that the
e p id e r m is w a s u n ab le to r e s i s t th e r a p id s w e llin g o f the c e l l s w ith in
d u rin g th e w a rm r a in y p e r io d .

T h u s, s u b se q u e n t c r a c k in g r e s u lt e d .

S tu d ie s r e p o r te d by B ell (3) on th e o r ig in o f r u s s e t in g o f

th e G o ld en R u s s e t a p p le , in d ic a te d th at p e r ic l in a l d iv is io n s o c c u r in the
e p id e r m is o f th is v a r ie t y n e a r fu ll b lo o m and su b se q u e n tly , an e p id e r m a l
la y e r o f 2 to 4 c e l l s in th ic k n e s s r e s u l t s .

E a r ly in July, th e in n e r m o s t

la y e r o f t h e s e c e l l s c o n tin u e s m e r is t e m a t ic a c t iv it y fo r m in g a v e r y a c tiv e
ca m b iu m w h ic h in tu rn fo r m s c o r k c e n tr ifu g a lly , g iv in g th e ty p ic a l r u s s e t e d
sk in o f th is v a r ie t y .
B ell la t e r (4) s tu d ie d r u s s e t in g o f th e M cIn to sh R ed v a r ie t y r e s u lt in g
fr o m b o r d e a u x s p r a y a p p lie d at about th e tim e o f fu ll b lo o m .

He c o n c lu d e d

th at th e f i r s t a p p a re n t in ju r y o c c u r r e d fro m 10 to 15 d a y s a fte r the sp r a y
a p p lic a tio n , w h ich w a s id e n tifie d a s a b ro w n in g o f the e p id e r m a l c e l l s a t th e
b a s e o f th e t r ic h o m e s .

B e c a u se c o n tin u ed g ro w th o f t h e s e c e l l s w a s in h ib ited ,

c r a c k in g r e s u lt e d fr o m su b se q u e n t fr u it e n la r g e m e n t w h ich in tu rn e x p o s e d
a d ja c e n t h y p o d e rm a l and c o r t ic a l t i s s u e .

T h is in itia te d an im m e d ia te s e r i e s

o f p e r ic lin a l d iv is io n s in th e h y p o d e r m a l c e l l s b e n e a th the tr ic h o m e e le v a t in g
th e in ju r e d t is s u e a b ove th e r e m a in d e r o f th e e p id e r m is .
A s th e fr u it c o n tin u e d to e n la r g e , he r e la t e d (4), th e c r a c k s m u lti­
p lie d , e x te n d e d ta n g e n tia lly and d e e p e n e d , r e s u lt in g in fu r th e r b ro w n in g
o f c e l l s and a d e e p e r fo r m a tio n o f m e r is t e m a t ic a c tiv ity in the c o r te x .
E v e n tu a lly , a c o r k ca m b iu m b e c a m e e v id e n t.

H e p o s tu la te d th at the fin a l

s c u r f - lik e p a tc h e s o f s c a r t is s u e w e r e a m ix tu r e o f d ea d e p id e r m is , h y p o ­
d e r m is , c o r te x , c o rk , and c o r k c a m b iu m s and th e r e fo r e w e r e not tr u e c o r k
but " rh y tid o m e" .

M a c D a n ie ls and H e in ic k e (29) in d ic a te d th at th e c o r k c o m e s fro m
a tr u e c o r k ca m b iu m w h ic h o r ig in a t e s s u b - e p id e r m a lly a ft e r le th a l f r e e z ­
in g o f th e e p id e r m a l c e l l s .
S tu d ie s on m a tu r e r u s s e t e d fr u it by V e r n e r (60) le a d one to
b e lie v e th at r u s s e t in g o c c u r s fo llo w in g in ju r y to th e c u t ic le .

H e sta te d ,

"A la y e r o f c o r k ca m b iu m a s s u m e s th e p o s itio n n o r m a lly o c c u p ie d by the
e p id e r m is , c u ttin g o ff to the o u ts id e s e v e r a l o r m a n y ta n g e n tia l la y e r s
o f c o r k c e l l s w h ic h c o n s titu te the s c u r f - lik e r u s s e t .

No p h e llo d e r m c o u ld

be o b s e r v e d in s id e th e c o r k cam b iu m and the h y p o d e r m is a p p e a r e d n o r m a l
b elo w th is m e r is t e m a t ic r e g io n ” .
V e r y r e c e n tly , S im o n s (55) c o n d u cted s tu d ie s o f r u s s e t e d
t is s u e o f G o ld en D e lic io u s c a u s e d by s e v e r e f r e e z in g te m p e r a tu r e s .

H is

e a r l i e s t o b s e r v a t io n s w e r e m a d e on s e c t io n s cu t a p p r o x im a te ly 5 w e e k s
a f t e r fu ll b lo o m .

H e n o tic e d s o m e d isr u p tio n o f e p id e r m a l c e l l s and s o m e

p e r ic lin a l d iv is io n s b elo w th e in ju r e d a r e a .

One m o n th a ft e r th is d ate,

m e r is t e m a t ic a c t iv it y had ta k en p la c e b e tw e e n th e n o r m a l and in ju r ed
t i s s u e s p r o d u c in g a ’’p e r id e r m " s e v e r a l c e l l - l a y e r s th ick .

" P erid erm "

c o n tin u e d to be fo r m e d th ro u g h o u t g ro w th and m a tu r ity o f th e fr u it.
S im o n s (55) s ta te d th at th e c u tic le v a r ie d in th ic k n e s s fr o m 8. 5 to 25. 6
m ic r o n s in July, r e a c h e d a v a r ia b le th ic k n e s s o f 12. 1 to 2 9 . 7 m ic r o n s

21.

by S e p te m b e r , a ft e r 'which tim e it d e c r e a s e d to a th ic k n e s s v a r y in g fro m
8. 3 to 2 5. 9 m ic r o n s at m a tu r ity .
A s n o ted by the r e v ie w o f lit e r a tu r e , a n u m b er o f s tu d ie s h a v e
b e e n m a d e on r u s s e t in g o f fr u it and fo r m a tio n o f c u tic le and c o r k y t is s u e .
No s tu d ie s w e r e fou nd that c le a r ly sh o w ed th e in te r a c tio n o f c o ld in ju ry
and th e u s e of c e r t a in p e s t ic id e s on fr u it r u s s e t in g a s s u g g e s te d by M itc h e ll
(3 3 ).

A ls o , no p u b lis h e d in fo r m a tio n w a s a v a ila b le e x p la in in g how r u s s e t ­

in g o c c u r s fo llo w in g th e u s e o f c e r ta in fu n g ic id e s a fte r a drop in a ir t e m ­
p e r a tu r e to 32° F o r lo w e r c lo s e to th e tim e o f b lo o m .

T here are q u es­

tio n s a s to w h e r e and how r a p id ly th e c u tic le d e v e lo p s on th e fr u it o f th e
a p p le and th e v a r ie t a l d if f e r e n c e s that m a y be p r e s e n t w ith r e s p e c t to
th is p r o t e c t iv e c o a tin g .

T h e r e fo r e , a stu d y w a s in itia te d to d e v e lo p a

b e tte r u n d e r sta n d in g o f s o m e o f th e s e p o in ts in q u e stio n .

M A T E R IA L S A N D M ETHODS

E x p e r im e n t 1.

C o n tr o lle d te m p e r a tu r e s tu d ie s to d e te r m in e th e r e la t io n ­

sh ip o f f r e e z in g a ir te m p e r a tu r e s and fu n g ic id e s on fr u it r u s s e t in g .
In A p r il o f 1956, w o o d en fr a m e s o f tw o by fo u r in ch lu m b e r w e r e
c o n s tr u c te d aro u n d b e a r in g , f o u r - y e a r - o ld a p p le t r e e s g r o w in g on M a ilin g
VII r o o ts to c k s lo c a te d at th e M ich ig a n S ta te U n iv e r s it y H o r tic u ltu r a l fa r m ,
E a s t L a n s in g , M ich ig a n (F ig u r e 1).

T h e to p s o f th e c a g e s w e r e c o v e r e d

w ith 0. 002 in c h p o ly e t h y le n e ^ fix e d p e r m a n e n tly in p la c e w ith w o o d -la th
s t r ip s .

T h e s id e s w e r e fitte d w ith r e m o v a b le p a n e ls c o v e r e d w ith th e s a m e

ty p e o f p o ly e th y le n e .

T w o t r e e s e a c h o f th e v a r ie t i e s Jonathan and G o ld en

D e lic io u s w e r e e n c lo s e d and a r e m a in in g t r e e o f e a c h v a r ie t y w a s e x p o s e d
to u n a lte r e d e n v ir o n m e n ta l c o n d itio n s to s e r v e a s a c o n tr o l.

A ll t r e e s w e r e

in g o o d b e a r in g v ig o r g r o w in g in a t r a s h y c u ltiv a tio n ty p e o f s o il m a n a g e ­
m e n t.
One c a g e e n c lo s in g e a c h v a r ie t y w a s eq u ip p ed w ith a t h e r m o s t a t ­
ic a lly c o n tr o lle d r e f r ig e r a t io n un it.

E a ch unit w a s c o m p o s e d o f an e ig h t-

o u n ce T e c u m s e h typ e F - l c o m p r e s s o r , o p e r a te d w ith a t h r e e - f o u r t h s h o r s e ­
p o w e r m o to r , a p r o d u ct o f th e T ec u m s e h M a n u fa ctu rin g C om pany, T e c u m se h ,

1/
— 0. 002 in ch p o ly e th y le n e o b ta in e d th ro u g h the c o u r t e s y o f th e B a k elite
D iv is io n o f U nion C a rb id e C o r p o r a tio n .

F ig u r e 1. P o ly e th y le n e c a g e s w ith r e m o v a b le p a n e ls e n c lo s in g a p p le t r e e s
g r o w in g on d w a r fin g r o o ts to c k s .

24.

M ich ig a n .

T he c o il u n its w e r e M od el WJ45 o f the Bush M a n u fa ctu r in g C o m ­

p a n y o f H a r tfo r d , C o n n e c tic u t and c o n ta in e d a la r g e fan fo r a ir c ir c u la tio n .
T h e t h e r m o s t a t e s w e r e ty p e T 4 91A 1 X 3 " A ir S w itch " , m a n u fa c tu r e d by
M in n e a p o lis -H o n e y w e ll R e g u la to r C om pany, M in n e a p o lis, M in n e so ta .

S m a ll

e le c t r ic a l, fan eq u ip p ed , G e n e r a l E le c t r ic s p a c e h e a t e r s w e r e a v a ila b le
fo r e a c h c a g e w hen h e a t w a s n e c e s s a r y .

T h e r e f r ig e r a t io n u n its w e r e d e ­

s ig n e d to lo w e r th e n igh t te m p e r a tu r e in the c a g e s to a d e s ir e d te m p e r a tu r e
b elow 32® F w hen n e c e s s a r y and the h e a te r s w e r e u s e d to p r e v e n t the t e m ­
p e r a tu r e w ith in th e c a g e s fr o m d ro p p in g lo w e r than w a s d e s ir e d .

T he r e ­

m o v a b le s id e p a n e ls w e r e p la c e d on th e c a g e s o n ly d u rin g th o se n ig h ts w hen
te m p e r a tu r e tr e a tm e n ts w e r e b e in g m a d e, o r w hen th e a ir te m p e r a tu r e w a s
p r e d ic t e d to drop to 32® F o r lo w e r .

In the la t t e r c a s e , one t r e e o f e a c h

v a r ie t y w a s e n c lo s e d and h e a te d w h ile the o th e r tr e e r e m a in e d e x p o s e d to
th e f r e e z in g t e m p e r a tu r e s .

T h e t r e e s w e r e e x p o s e d at o th e r t im e s d u r ­

in g the g r o w in g s e a s o n .
T h e t r e e s w e r e p r u n ed to d iv id e th e b e a r in g s u r f a c e s in to tw o
d is tin c t h a lv e s s o th at tw o fu n g ic id e tr e a tm e n ts c o u ld be e v a lu a te d in th e
s a m e e n v ir o n m e n t.
B e c a u se o f u n fa v o r a b le p o llin a tio n w e a th e r d u rin g the b loom
p e r io d o f Jonathan, o n ly G o ld en D e lic io u s , w h ich b lo s s o m e d la t e r d u rin g
m o r e fa v o r a b le c o n d itio n s , w a s u s e d in the s tu d ie s in 1956.

25.

T h e tr e a tm e n ts e x p r e s s e d a s a m o u n ts p e r 100 g a llo n s o f sp r a y
m ix tu r e w e r e a s fo llo w s :
T h r e e a p p lic a tio n s o f P h ix at fo u r o u n c e s p lu s w e tta b le s u lfu r at
th r e e p ou n d s w e r e m a d e u n ifo r m ly on a ll t r e e s th rou gh d e la y e d d o rm a n t.
B egin n in g w ith e a r ly p r e -p in k , e ig h t a p p lic a tio n s o f the c o m p a r is o n t r e a t ­
m e n ts o f ca p ta n at tw o p ou n d s and g ly o d in at one flu id qu art w e r e m a d e on
o n e - h a lf o f e a c h o f th e th r e e G old en D e lic io u s t r e e s .
a s the c o n tr o l tr e a tm e n t.

T h e cap tan s e r v e d

B egin n in g at p e ta l fa ll, tw o p ou nds o f m e th o x y c h lo r

w a s u s e d u n ifo r m ly in th e la s t fo u r fu n g ic id e a p p lic a tio n s .

F iv e a d d itio n a l

s p r a y s o f tw o p ou n d s o f m e th o x y c h lo r w e r e n e c e s s a r y in July and A u g u st fo r
in s e c t c o n tr o l.

A s e p a r a te s in g le a p p lic a tio n o f 25 p e r c e n t w e tta b le m a la -

th ion at tw o p ou n d s p lu s fou r flu id o u n c e s o f T r ito n B -1 9 5 6 a s a w e ttin g
a g e n t w a s m a d e on June 19 b e tw e en the s e c o n d and th ird c o v e r s p r a y s to
c o n tr o l g r e e n a p p le a p h id s (A p h is p o m i, D e G e e r ).
T h e th r e e a p p lic a tio n s p r io r to e a r ly p r e - p in k w e r e m a d e w ith
a John Bean N o. 40 S p eed S p r a y e r (the John Bean D iv is io n o f F o o d M a c h in e r y
and C h e m ic a l C o r p o r a tio n , L a n sin g , M ich ig a n ).

A ll su b se q u e n t a p p lic a tio n s

w e r e m a d e w ith a M y e r s S ilv e r P r in c e m o to r -p o w e r e d w h e e lb a r r o w s p r a y e r
(F . E . M y e r s B r o th e r s C om pany, A sh la n d , O hio) o p e r a tin g at 150 pounds
p r e s s u r e eq u ip p ed w ith an a d ju sta b le n o z z le hand gun.

A c a n v a s c u r ta in

w a s u s e d to s e p a r a te th e h a lv e s o f e a c h t r e e w h ile a p p ly in g th e fu n g ic id e

26.

t r e a tm e n ts to a v o id c o n ta m in a tio n fr o m d r ift.
M axim u m and m in im u m te m p e r a tu r e s w e r e r e c o r d e d in s id e th e
c a g e s w ith T a y lo r th e r m o m e t e r s (T a y lo r In stru m e n t C om pany, R o c h e s te r ,
N ew Y o r k ) p la c e d in th e c e n tr a l p o r tio n o f th e t r e e .

C ontin u ou s r e c o r d in g

o f te m p e r a tu r e and h u m id ity w a s o b ta in e d w ith a F r ie z m o d e l 594 H y g r o th e r m o g r a p h ( F r ie z In str u m e n t D iv is io n , B endix A v ia tio n C o rp o ra tio n ,
B a ltim o r e , M a ry la n d ), w h ic h w a s p la c e d in e a c h c a g e n e a r th e ed g e o f th e
t r e e a p p r o x im a te ly fiv e f e e t from th e grou n d .
A t h a r v e s t tim e , a ll th e fr u its fro m e a c h tr e a tm e n t w e r e p ic k e d
and th e f in is h o f th e fr u it w a s e v a lu a te d and r a te d a s fr e e o f r u s s e tin g ,
lig h tly r u s s e t e d , o r h e a v ily r u s s e t e d .

F ifty to s e v e n t y - f iv e fr u it s w e r e

e v a lu a te d fr o m e a c h h a lf - t r e e tr e a tm e n t.
L ig h t r u s s e t in g r e f e r s to the am ou n t o f r u s s e t in g a llo w a b le in
th e g r a d e o f U . S. N o. 1, o r h ig h e r , and a s d e s c r ib e d by th e M ich ig a n A p p le
M a r k e tin g Law A c t 132, P. A . 1937: A ny a m o u n t i s p e r m itte d in th e ste m
c a v ity o r c a ly x b a s in w h ich can n ot be s e e n w h en th e a p p le i s p la c e d on a
fla t s u r fa c e e x c e p t w h en e x c e s s i v e l y ro u g h o r b a r k lik e o r w h en the a p p e a r ­
a n c e i s m a t e r ia lly a ffe c te d .
1.

A m o u n ts p e r m itte d o u tsid e c a v itie s :

Sm ooth, n e tlik e ; to ta l a r e a o f 25 p e r c e n t o f s u r fa c e , if

p a tte r n and c o lo r show no m a r k e d c o n tr a s t w ith b a ck g ro u n d
c o lo r .

27.

2. Sm ooth, so lid ; to ta l a r e a 25 p e r c e n t o f s u r fa c e , if p a tte r n
and c o lo r sh ow no m a r k e d c o n tr a s t w ith b a ck g ro u n d .
3. S lig h tly rough; to ta l a r e a o n e - h a lf in ch in d ia m e te r .
4. Rough; o n e -q u a r te r in ch in d ia m e te r .
H e a v y r u s s e t in g d is q u a lif ie s th e fr u it fo r th e g r a d e o f U. S. No. 1
o r h ig h e r .

F r e e o f r u s s e t in g b e in g s e lf -e x p la n a t o r y ,

F ig u r e 2 g iv e s an

e x a m p le o f lig h t and h eavy r u s s e tin g .
T o fu r th e r e v a lu a te th e e f f e c t s o f g ly o d in and ca p ta n on r u s s e t in g
o f G o ld en D e lic io u s u n d er f ie ld c o n d itio n s , a t h ir t y - y e a r - o ld tr e e lo c a te d
a p p r o x im a te ly 500 fe e t fr o m th e c a g e t r e e s , w a s d iv id e d into tw o eq u a l h a lv e s
fo r th e tw o sp r a y tr e a tm e n ts .
T h e s p r a y c h e m ic a ls , th e a m o u n ts u s e d and the d a te s o f a p p lic a ­
tio n w e r e th e s a m e a s fo r th e c a g e t r e e s .

H o w e v er , an a d d itio n a l s e p a r a te

a p p lic a tio n o f EPN at one pound p e r 100 g a llo n s o f s p r a y m ix tu r e w a s n e c e s ­
s a r y in A u g u st to c o n tr o l tw o -s p o tte d s p id e r m ite (T e tr a n y c h u s b im a c u la tu s,
H a r v ey ) and E u r o p e a n r e d m ite (P a r a te tr a n y c h u s p ilo s u s , C a n e s tr in i and
F a n z a g o ).
T h e a p p lic a tio n s w e r e m a d e u s in g an a d ju sta b le n o z z le gun a tta c h e d
to a John Bean N o. 26 S p ee d S p r a y e r eq u ip p ed w ith a 1 5 -g a llo n p e r m in u te
pum p o p e r a tin g at 4 0 0 p ou n d s p r e s s u r e .

T h ey w e r e m a d e on d a y s w hen the

w ind w a s r e la t iv e ly c a lm and th e t r e e w a s s p r a y e d to p r e v e n t d r ift fr o m one
tr e a tm e n t to th e o th e r .

28.

F ig u r e 2. A p p le f r u it s r e p r e s e n tin g lig h t and h e a v y r u s s e tin g . T he a p p le on
th e le ft s h o w s th e m a x im u m a llo w a b le am ount o f r u s s e t in g that ca n
be te r m e d " lig h t r u s s e tin g " . T h e a p p le on th e r ig h t illu s t r a t e s a
h e a v ily r u s s e t e d a p p le .

A t h a r v e s t tim e , fr u it fr o m th e c e n tr a l p o r tio n o f e a c h o n e - h a lf
o f th e t r e e s p r a y e d w ith th e s e p a r a t e fu n g ic id e s w e r e p ic k e d and e v a lu a te d
fo r r u s s e t in g a s p r e v io u s ly d e s c r ib e d .

A p p r o x im a te ly 7 0 0 a p p le s w e r e

e x a m in e d fr o m e a c h tr e a tm e n t.

E x p e r im e n t 2 .

F ie ld s tu d ie s to e v a lu a te th e e f f e c t s o f fu n g ic id e s and f r e e z ­

in g a ir te m p e r a tu r e s on fr u it r u s s e t in g o f a p p le s .
A m ix e d b lo c k o f s ix t e e n - y e a r - o l d a p p le t r e e s a t the M ich ig a n
S ta te U n iv e r s it y G rah am E x p e r im e n t S ta tio n , G ran d R a p id s, w a s s e le c t e d
fo r f ie ld s tu d ie s in 1 9 5 6 .

T h e b lo c k in c lu d e d G o ld en D e lic io u s , Jonathan

and M cIn to sh , and w a s d iv id e d to p r o v id e fiv e s in g le t r e e r e p lic a t e s o f e a c h
v a r ie t y fo r fo u r p e s t ic id e tr e a tm e n ts .

T h e fu n g ic id e s u s e d a s th e t r e a t ­

m e n ts w e r e (1) th ir a m , (2) g ly o d in , (3) ca p ta n , and (4) ca p ta n fo llo w e d by
g ly o d in a fte r f i r s t c o v e r .

T h e s p r a y p r o g r a m e x p r e s s e d a s a m o u n ts p e r

100 g a llo n s o f s p r a y m ix tu r e w a s a s fo llo w s :
T w o a p p lic a tio n s o f liq u id li m e - s u l f u r at e ig h t q u a rts w e r e m a d e
u n ifo r m ly on a l l t r e e s p r io r to p r e -p in k .

T w o s u c c e e d in g tr e a tm e n ts b e fo r e

fu ll b loom c o n s is t e d o f ca p ta n a t tw o p ou n d s, th ira m a t tw o p ou n d s, and
g ly o d in a t on e q u art.

A fte r b lo o m , s e v e n s p r a y s o f ca p ta n a t one pound,

th ir a m a t o n e pound, and g ly o d in a t o n e p in t w e r e m a d e on th e tr e a tm e n t
p lo t s .

P h ygon at fo u r o u n c e s w a s in c lu d e d w ith e a c h o f th e tr e a tm e n t fu n g i-

30.

c id e s in th e p e ta l fa ll, f ir s t , and th ir d c o v e r s p r a y s .

One pound o f p a r a -

th ion w a s u s e d in the s e c o n d and th ir d c o v e r s p r a y s w ith th e th ir d c o v e r
r e c e iv in g in ad d itio n , o n e pound o f D D T .

On June 28, a ll tr e a tm e n ts r e ­

c e iv e d an e x tr a s p r a y of a r a m ite at o n e pound, O votran at o n e -h a lf pound,
and D D T at o n e and o n e - h a lf p ou n d s w ith no fu n g ic id e s b e in g u s e d .

T he

la s t th r e e c o v e r s p r a y s in c lu d e d w ith the fu n g ic id e tr e a tm e n ts , le a d a r s e n ­
a te at tw o p ou n d s w ith the la s t c o v e r r e c e iv in g in a d d itio n , D D T at one and
o n e - h a lf p o u n d s.

W hen le a d a r s e n a t e w a s in c lu d e d w ith g ly o d in , fe r r o u s

s u lfa te at o n e -h a lf pound w a s ad d ed to p r e v e n t p o s s ib le a r s e n ic a l in ju ry .
A n o th er b lo c k o f s e v e n - y e a r - o ld a p p le t r e e s w a s d iv id e d into th r e e
p lo t s .

E a ch o f th e s e p lo t s w a s d iv id e d into s u b - p lo ts so a s to c o n ta in fiv e

t r e e s o f e a c h o f the tw o v a r ie t ie s , M cIn to sh and Jonathan.

One s u b -p lo t o f

e a c h p lo t w a s tr e a te d w ith cap tan and th e r e m a in in g s u b - p lo ts o f the p lo ts
in c lu d e d g lyod in , th ira m and fe r b a m a s the sp r a y tr e a tm e n ts .

T h e a m o u n ts

and t im e s o f a p p lic a tio n o f sp r a y m a t e r ia ls u s e d in th e s e p lo t s w e r e the
s a m e a s in th e b lo c k of s ix t e e n - y e a r - o l d t r e e s , e x c e p t fo r the added ferb a m
tr e a tm e n t.

F e r b a m w a s u s e d at one and o n e -h a lf pounds p e r 100 g a llo n s

p r io r to b lo o m , and w a s d e c r e a s e d to th r e e -fo u r th s o f a pound b e g in n in g
w ith p e ta l fa ll.
T h e sp r a y m a t e r ia ls o f a ll tr e a tm e n ts at th e G raham E x p e r im e n t
S ta tio n w e r e a p p lie d w ith a R o b in so n a ir - b l a s t a tta ch m en t on a H a rd ie s p r a y e r

e q u ip p e d w ith a th ir ty g a llo n s p e r m in u te pum p o p e r a tin g a t 6 0 0 p ou n d s p r e s ­
su re.
A ir te m p e r a tu r e s w e r e o b ta in e d fr o m th e r m o g r a p h r e c o r d s o f th e
s ta tio n lo c a te d n e a r th e t e s t o r c h a r d s .

T h e e le v a tio n o f th e s p r a y p lo t s and

r e c o r d in g in s tr u m e n t d id n ot v a r y g r e a t ly .
A t h a r v e s t tim e a b u sh e l o f fr u it w a s p ic k e d r a n d o m ly fr o m e a c h
s in g le t r e e r e p lic a t e in e a c h tr e a tm e n t.

T h is fr u it w a s e x a m in e d and r u s s e t ­

in g r e c o r d s w e r e tak en , a s d e s c r ib e d in E x p e r im e n t 1.

E x p e r im e n t 3.

C o n tr o lle d te m p e r a tu r e s tu d ie s in 1957 to fu r th e r e v a lu a te

th e in flu e n c e o f fu n g ic id e s and f r e e z in g a ir te m p e r a tu r e s on fr u it r u s s e tin g .
T h e s a m e t r e e s and c a g e s a s d e s c r ib e d in E x p e r im e n t 1 w e r e
u s e d in t h e s e s tu d ie s e x c e p t, due to u n fa v o r a b le w e a th e r in g o f th e p o ly e th y le n e ,
th e to p s o f th e c a g e s had to b e r e p la c e d .

A c le a r p la s t ic film . 010 in c h th ic k

o f " P o ly fle x II" p r o d u c e d by P la x C o r p o r a tio n , H a rtfo rd , C o n n e c tic u t w a s u s e d
to r e c o v e r th e to p s.

T h e r e m o v a b le s id e p a n e ls r e m a in e d c o v e r e d w ith th e

. 002 in ch p o ly e th y le n e .

T h e r e f r ig e r a t io n and h e a tin g u n its w e r e the s a m e

a s p r e v io u s ly d e s c r ib e d .
T h e t r e e s w e r e p r u n ed to d iv id e th e b e a r in g s u r f a c e s into two
d is tin c t h a lv e s s o th a t tw o fu n g ic id e tr e a tm e n ts c o u ld be e v a lu a te d in th e
s a m e e n v ir o n m e n t.

32.

T h e Jonathan and G o ld en D e lic io u s had s u ffic ie n t fr u it on th e t r e e s
to be u s e d fo r fu n g ic id e tr e a tm e n ts .

T h e a m o u n ts o f fu n g ic id e s u se d in the

tr e a tm e n ts on G o ld en D e lic io u s e x p r e s s e d a s a m o u n ts p e r 100 g a llo n s of
s p r a y m ix tu r e w e r e a s fo llo w s :
A t th e g r e e n - t ip s ta g e , Phygon at o n e -h a lf pound w a s a p p lie d u n i­
fo r m ly on a ll t r e e s .

W etta b le s u lfu r at th r e e p ou n d s p lu s fo u r o u n c e s of

P h ix w a s u s e d at d e la y e d d o rm a n t.

S ta r tin g w ith the p in k s ta g e o f d e v e lo p ­

m en t, o n e -h a lf o f e a c h o f the th r e e t r e e s w a s s p r a y e d w ith g ly o d in at one
q u art.

T h e r e m a in in g o n e -h a lf of e a c h tr e e w a s s p r a y e d w ith g ly o d in at

on e p in t, p lu s fo u r o u n c e s of Phygon.

T h e s e a m o u n ts w e r e co n tin u ed fo r

e ig h t a p p lic a tio n s (th rou gh fou rth c o v e r ), a fte r w h ich th e t r e e s w e r e s p r a y e d
u n ifo r m ly fo r tw o m o r e c o v e r s p r a y s w ith g ly o d in at on e p in t.

M e th o x y c h lo r

a t tw o p ou n d s w a s in c lu d e d u n ifo r m ly in a ll m ix t u r e s s ta r tin g w ith f ir s t
cover.

T w o a d d itio n a l s p r a y s o f m a la th io n a t tw o p ou nds p lu s m e th o x y c h lo r

a t tw o p ou nds w e r e n e c e s s a r y fo r in s e c t c o n tr o l a fte r the fu n g ic id e a p p li­
c a tio n s w e r e c o m p le te d .

A fou rth G o ld en D e lic io u s tr e e o u tsid e o f the c a g e s

w a s s p r a y e d w ith cap tan at th e s a m e tim e a s th e s e th r e e t r e e s ju st d is c u s s e d .
T h is s e r v e d a s a c o n tr o l tr e a tm e n t to be c o m p a r e d w ith the r e s u lt s o f E x p e r ­
im e n t 1 co n d u cted in 1956.
T he tr e a tm e n ts on the th r e e Jonathan t r e e s e x p r e s s e d a s a m o u n ts
p e r 100 g a llo n s o f s p r a y m ix tu r e w e r e a s fo llo w s :

33.

At th e g r e e n - t ip s ta g e , P hygon at o n e -h a lf pound w a s u s e d u n i­
fo r m ly on a ll t r e e s .

W etta b le s u lfu r a t th r e e p ou nds p lu s fo u r o u n c e s o f

P h ix w a s u s e d on a ll t r e e s at d e la y e d d o rm a n t.

S ta r tin g w ith p r e -p in k , h a lf

o f e a c h o f th e th r e e t r e e s w a s s p r a y e d w ith g ly o d in a t on e qu art and th e
o th e r h a lf w ith ca p ta n at tw o p ou n d s.

T h e s e tr e a tm e n ts w e r e co n tin u ed

fo r e ig h t m o r e s p r a y s o r th rou gh fo u rth c o v e r .

In the fifth and six th c o v e r

s p r a y s , cap tan w a s r e d u c e d to one pound and g ly o d in to on e p in t.

M e th o x y ­

c h lo r at tw o p ou n d s w a s ad d ed u n ifo r m ly to a ll tr e a tm e n ts s ta r tin g w ith f i r s t
c o v e r fo r in s e c t c o n tr o l.

T w o a d d itio n a l s p r a y s o f m e th o x y c h lo r at two

p o u n d s and m a la th io n at tw o p ou n d s w ithout the fu n g ic id e s w e r e n e c e s s a r y
d u rin g July and A u g u st fo r in s e c t c o n tr o l.
T h e tw o a p p lic a tio n s p r io r to p r e -p in k on both v a r i e t ie s w e r e
m a d e w ith a John Bean N o. 26 S p eed S p r a y e r .

A ll su b se q u e n t a p p lic a tio n s

w e r e m a d e w ith th e m o to r -p o w e r e d w h e e lb a r r o w s p r a y e r d e s c r ib e d in
E x p e r im e n t 1.

H e r e a ls o a c a n v a s c u r ta in w a s u s e d to s e p a r a te the h a lv e s

o f e a c h t r e e w h ile a p p ly in g the fu n g ic id e tr e a tm e n ts to a v o id c o n ta m in a tio n
fro m d rift.
T e m p e r a t u r e s w e r e r e c o r d e d w ith th e u s e o f a th e r m o c o u p le
p la c e d w ith in a b lo s s o m c lu s t e r in the c e n tr a l p o r tio n o f e a c h t r e e .
A c o n tin u o u s ly o p e r a tin g M in n e a p o lis-H o n e y w e ll r e c o r d e r w a s
c o n n e c te d to th e th e r m o c o u p le s so that te m p e r a tu r e s c o u ld be r e c o r d e d

34.

c o n tin u o u s ly fr o m e a c h t r e e th ro u g h o u t th e p e r io d o f d e la y e d d o rm a n t th ro u g h
secon d co v er.

A F r ie z h y g r o th e r m o g r a p h w a s a ls o u s e d in a s m a ll w e a th e r

h o u s e a m o n g th e t r e e s to k eep a s e a s o n a l r e c o r d o f a ir t e m p e r a tu r e s .
fu r th e r c h e c k ,

As a

T a y lo r m a x im u m -m in im u m th e r m o m e te r s w e r e o p e r a te d

w ith in th e c e n te r o f e a c h t r e e o f th e stu d y .
A t h a r v e s t tim e , th e fr u it fr o m e a c h tr e a tm e n t w a s p ic k e d and
e v a lu a te d fo r th e p r e s e n c e o f s u r fa c e r u s s e t in g , a s d e s c r ib e d in E x p e r i­
m e n t 1.

E x p e r im e n t 4.

F u r th e r f ie ld s tu d ie s to d e te r m in e th e e f f e c t s o f fu n g ic id e s

and f r e e z in g a ir te m p e r a tu r e s on fr u it r u s s e tin g .
T h e s a m e b lo c k o f you n g a p p le t r e e s o f Jonathan and M cIn to sh
a t th e M ic h ig a n S ta te U n iv e r s it y G rah am E x p e r im e n t S ta tio n th at w a s u s e d
in 1956 w a s a g a in u s e d in 1957 fo r fu r th e r e v a lu a tio n s .
w a s a g a in d iv id e d in to th r e e p lo t s .

T he m a in b lo c k

T h e s e p lo t s w e r e d iv id e d in to tw o s u b ­

p lo t s o f fiv e s i n g l e - t r e e r e p lic a t io n s o f e a c h v a r ie t y .

One s u b -p lo t o f e a c h

p lo t r e c e iv e d ca p ta n a s a c o n tr o l tr e a tm e n t and the th r e e o th e r s u b -p lo ts
w e r e s p r a y e d w ith th ir a m , g ly o d in and w e tta b le s u lfu r a s th e fu n g ic id e
t r e a tm e n ts .
T h e s p r a y p r o g r a m e x p r e s s e d a s a m o u n ts p e r 100 g a llo n s o f s p r a y
m ix tu r e w a s a s fo llo w s :

35*

T w o a p p lic a tio n s o f liq u id lim e - s u l f u r at e ig h t q u a r ts w e r e m a d e
u n ifo r m ly on a ll t r e e s p r io r to p r e -p in k .

S ta r tin g at pink, th e tr e a tm e n ts

w e r e th ir a m at on e and o n e - h a lf p o u n d s, g ly o d in at one q u art, w e tta b le s u l ­
fur at s ix p ou n d s, and ca p ta n at tw o p o u n d s.

T h is r a te w a s u s e d fo r fo u r

a p p lic a tio n s (th rou gh s e c o n d c o v e r ) a fte r w h ich the a m o u n ts w e r e r e d u c e d
by o n e -fo u r th fo r fiv e a d d itio n a l s p r a y s .

Phygon a t fou r o u n c e s w a s ad d ed

to a ll tr e a tm e n ts at p e ta l fa ll, and P h ix at fou r o u n c e s w a s u s e d u n ifo r m ly
at fir s t c o v e r .

S ta r tin g w ith se c o n d c o v e r , p a r a th io n at one pound, and

D D T at on e pound w a s ad d ed to a ll tr e a tm e n ts .
A s e p a r a te s in g le a p p lic a tio n o f D D T at one and o n e -h a lf pou n d s
w a s m ad e in A u g u st fo r in s e c t c o n tr o l.

L ead a r s e n a t e a t tw o pou n d s w a s

u s e d in th e fifth and s ix th c o v e r s p r a y s in p la c e o f p a r a th io n .

W hen le a d

a r s e n a t e w a s u s e d in th e g ly o d in tr e a tm e n t, ferb a m at o n e -h a lf pound w a s
a d d ed to p r e v e n t p o s s ib le a r s e n ic a l in ju ry .
A ll sp r a y a p p lic a tio n s w e r e m a d e w ith a R o b in so n a ir - b l a s t a tta c h ­
m e n t on a H a r d ie s p r a y e r eq u ip p ed w ith a th ir t y - g a llo n s p e r m in u te pum p
o p e r a tin g at 600 p ou n d s p r e s s u r e .
A ir te m p e r a tu r e s w e r e o b ta in e d fro m the th e r m o g r a p h r e c o r d s of
th e s ta tio n lo c a te d n e a r the t e s t b lo c k .

T h e e le v a t io n s o f the sp r a y p lo ts and

th e r e c o r d in g in s tr u m e n t w e r e s im ila r .
At h a r v e s t tim e , a b u sh e l o f fr u it w a s p ic k e d r a n d o m ly fro m e a c h
s in g le t r e e r e p lic a tio n in e a c h tr e a tm e n t and e x a m in e d fo r p o s s ib le r u s s e t in g
a s d e s c r ib e d in E x p e r im e n t 1.

36.

H is t o lo g ic a l I n v e s tig a tio n s

E x p e r im e n t 5.

H is t o lo g ic a l in v e s t ig a t io n s to stu d y th e d e v e lo p m e n t o f the

p r o te c tiv e la y e r s o f G o ld en D e lic io u s , Jonathan, and M cIn to sh w ith s p e c ia l
a tte n tio n g iv e n to th e c u tic le , and to stu d y th e d e v e lo p m e n t o f r u s s e t e d t i s ­
s u e s o f th e fr u it.
F lo w e r s and fr u it s s e le c t e d fo r th is stu d y w e r e ta k en fro m th ir t y y e a r - o ld b e a r in g G o ld en D e lic io u s , Jonathan, and M cIn to sh a p p le t r e e s lo c a t ­
ed at th e M ich ig a n S ta te U n iv e r s it y H o r tic u ltu r a l fa r m , E a s t L a n sin g .

A ll

t r e e s r e c e iv e d a u n ifo rm s p r a y tr e a tm e n t o f captan , D D T and p a r a th io n
th rou gh ou t th e g r o w in g s e a s o n .

B lo sso m c lu s t e r s fro m w h ic h s a m p le s w e r e

c o lle c t e d w e r e fro m s p u r s on v ig o r o u s th r e e - o r f o u r - y e a r - o ld w ood lo c a te d
on th e sou th s id e o f th e tr e e a t a h e ig h t o f fiv e to s e v e n fe e t.

F o u r c o m p le te

flo w e r c lu s t e r s w e r e ta k en tw ic e w e e k ly fro m e a c h v a r ie t y fr o m th e f ir s t
s ta g e o f bud s w e llin g to p r e -p in k .

A fte r p r e -p in k the c e n tr a l b lo s s o m of

fo u r c lu s t e r s w e r e c o lle c t e d tw ic e w e e k ly fr o m e a c h v a r ie t y u n til one m on th
a fte r fu ll b lo o m .

T h e s u c c e e d in g s a m p le s w e r e c o lle c t e d w e e k ly u n til h a r ­

v e s t tim e .
I m m e d ia te ly a fte r r e m o v a l fro m th e tr e e , th e p la n t m a t e r ia l w a s
p la c e d in la b e le d b o t tle s c o n ta in in g a k illin g and fix in g s o lu tio n o f fiv e m i l l i ­
l i t e r s o f fo r m a lin , fiv e m i l l i l i t e r s o f g la c ia l a c e t ic a c id and n in e ty m i l l i l i t e r s

37.

o f s e v e n ty p e r c e n t e th y l a lc o h o l.

T h e m a t e r ia l w a s th en p la c e d in a la r g e

e v a c u a to r and h e ld u n d er v a cu u m fo r a p p r o x im a te ly th r e e h o u r s .

T he

vacu u m p la c e d on th e m a t e r ia l w a s in c r e a s e d g r a d u a lly to p r e v e n t d a m a g e
to the t is s u e s tr u c tu r e .

A fte r th e m a t e r ia l w a s e v a c u a te d , th e o r ig in a l

s o lu tio n o f f o r m a lin - a c e t ic a c id - a lc o h o l w a s r e p la c e d w ith a f r e s h s o lu tio n .
T h e m a t e r ia l w a s s to r e d fo r v a r y in g p e r io d s o f tim e b e fo r e e m b e d d in g
in t is s u e m a t .
O th er s a m p le s o f f r e s h flo w e r s and fr u it s , s e le c t e d in th e m a n n e r
ju st d e s c r ib e d , w e r e p la c e d in la b e le d p o ly e th y le n e b a g s, s e a le d , and s to r e d
a t 0" F fo r fu tu r e s tu d ie s o f f r e s h m a t e r ia l u s in g th e f r e e z in g m ic r o to m e .
T h e k ille d and fix e d m a t e r ia l w a s d eh y d ra ted u s in g th e t e r t ia r y
b u tyl a lc o h o l m e th o d a s d e s c r ib e d by Joh an sen (27) and e m b e d d ed in F is h e r
tis s u e m a t h a v in g a m e ltin g p o in t o f 5 4 -5 6 ^ C .

A fte r e m b ed d in g , the m a t e r ­

ia l w a s s to r e d in th e f r e e z in g c o m p a r tm e n t o f a r e f r ig e r a t o r fo r tw o d a y s
to p r e v e n t c r y s t a lliz a t io n o f th e p a r a ffin .

T h e m a t e r ia l w a s th en s e c tio n e d

u s in g a M odel 820 A m e r ic a n O p tica l C om p an y r o ta r y m ic r o to m e .

T he

s e c t io n s w e r e cut s ix to te n m ic r o n s in th ic k n e s s , d ep en d in g upon th e a g e
o f the p lan t m a t e r ia l and th e r e la t iv e s iz e o f th e c e l l s .

Both t r a n s v e r s e

and lo n g itu d in a l s e c t io n s w e r e m a d e o f the d e v e lo p in g fr u it o r flo w e r r e c e p ­
t a c le s .

S e r ia l s e c t io n s w e r e th en a ffix e d to sta n d a rd m ic r o s c o p e s lid e s

u s in g Haupt*s a d h e s iv e (27).

T h e p a r a ffin w a s r e m o v e d fr o m th e s e c t io n s w ith x y lo l and the
s e c t io n s w e r e s ta in e d w ith S a fra n in and F a s t G r e e n a s o u tlin e d by J o h a n sen
(2 7 ).

T h e s e c t io n s w e r e m o u n ted in c la r it e , a s y n th e tic r e s in , and a llo w e d

to d ry fo r tw o d a y s p r io r to m ic r o s c o p ic e x a m in a tio n .
T h e fr o z e n m a t e r ia l w a s r e m o v e d fr o m th e 0e F s to r a g e and
p la c e d in to a s a tu r a te d a b s o lu te e th y l a lc o h o l s o lu tio n o f Sudan IV fo r 10
m in u te s .

T h e e x c e s s s ta in w a s th en r in s e d o ff w ith 95 p e r c e n t e th y l a lc o h o l

and th e p la n t m a t e r ia l w a s p la c e d im m e d ia te ly in a ten p e r c e n t g e la tin s o lu ­
tio n on th e s ta g e o f a M od el 880 A m e r ic a n O p tica l C om pany f r e e z in g m ic r o ­
to m e .

T h e p la n t m a t e r ia l w a s th en r e f r o z e n and t r a n s v e r s e s e c t io n s cut

a t s i x m ic r o n s in th ic k n e s s .
T h e s e c t io n s w e r e m o u n ted in w a te r on sta n d a rd m ic r o s c o p e s lid e s
a c o v e r - s l i p p la c e d on th em , and th e e x c e s s w a te r b lo tte d off.

The ed g es of

th e c o v e r - s l i p w e r e th en s e a le d w ith c le a r fin g e r n a il p o lis h and a llo w e d to
d r y fo r a p p r o x im a te ly fif te e n m in u te s b e fo r e e x a m in a tio n .
A ll m ic r o s c o p ic e x a m in a tio n s w e r e m a d e w ith a Z e i s s 2 5 0 1 9 0
m ic r o s c o p e .

T h e p e r m a n e n tly p r e p a r e d m a t e r ia l w a s e x a m in e d a s s e r ia l

s e c t io n s to o b ta in a tr u e p r o s p e c t iv e o f th e p r o te c tiv e la y e r s o f the fr u it.
P h o to m ic r o g r a p h s w e r e ta k en w ith an E xak ta VX c a m e r a w ith a
m ic r o s c o p e a d a p te r .

A ty p e 3 1 - 3 3 - 2 6 B au sch and L om b O p tica l C om pan y

m ic r o s c o p e lig h t w a s u s e d a s th e lig h t s o u r c e in c lu d in g a grou n d g la s s

39.

f il t e r (3 9 3 7 5 ) and a b lu e g la s s f i l t e r (3 9 3 7 0 ) b e tw e e n th e lig h t s o u r c e and
s u b - s t a g e m ir r o r o f the m ic r o s c o p e .

K odak P lu s - X film w a s u s e d fo r ta k in g

b la c k and w h ite p h o to m ic r o g r a p h s and K o d a ch ro m e (d a y lig h t typ e) film w a s
u s e d fo r ta k in g c o lo r e d p h o to m ic r o g r a p h s .
C o m p a r a tiv e o b s e r v a t io n s w e r e m a d e on the th r e e v a r ie t ie s
s tu d ie d r e la t iv e to c u t ic le d e v e lo p m e n t, tr ic h o m e s tr u c tu r e and m eth o d o f
tr ic h o m e e lim in a tio n fr o m th e fr u it s u r fa c e , typ e o f e p id e r m a l and h y p o d e r m a l la y e r s , and th e p r o g r e s s iv e c h a n g e s that o c c u r in th e s e t is s u e s a s
the fr u it e n la r g e s .
T he fr u its u s e d in the h is t o lo g ic a l stu d y o f the d e v e lo p m e n t o f
r u s s e t e d t i s s u e s w e r e c o lle c t e d fro m the t h ir t y - y e a r - o ld G o ld en D e lic io u s
a p p le t r e e s r e c e iv in g th e g ly o d in tr e a tm e n t a s d e s c r ib e d in E x p e r im e n t 1.
S a m p le s w e r e c o lle c t e d w e e k ly s ta r tin g tw o w e e k s a fte r fu ll b loom and c o n ­
tin u in g u n til h a r v e s t m a tu r ity .

T h e p r o c e d u r e s fo r p r e p a r in g the m a te r ia l

fo r m ic r o s c o p ic e x a m in a tio n w e r e th e s a m e a s p r e v io u s ly d e s c r ib e d fo r th e
p e r m a n e n tly m o u n ted s e c t io n s .

P h o to m ic r o g r a p h s w e r e ta k en a ls o , a s p r e ­

v io u s ly d e s c r ib e d .
O b s e r v a tio n s w e r e m ad e r e la t iv e to tim e o f the e a r l i e s t r e c o g n iz ­
a b le r u s s e t d e v e lo p m e n t, th e a c tu a l fo r m a tio n o f r u s s e t e d t i s s u e and th e
fin a l typ e of t i s s u e s r e s u lt in g in the r u s s e t e d a r e a s .
T o m o r e fu lly e v a lu a te th e r o le of in ju ry o f t r ic h o m e s in fr u it

40.

r u s s e t in g , m a c r o s c o p ic s tu d ie s w e r e c o n d u c te d on la r g e t h i r t y - y e a r - o l d
G o ld en D e lic io u s and Jonathan a p p le t r e e s g r o w in g on th e M ic h ig a n S ta te
U n iv e r s it y H o r tic u ltu r a l fa r m .

A m in im u m o f te n flo w e r s at e a c h o f th e

s t a g e s , pink, fu ll b lo o m , and p e ta l fa ll w e r e s e le c t e d fo r th is stu d y .

W ith

the a id o f a hand le n s e and s h a r p -p o in te d t w e e z e r s , th e fin e m a t o f t r ic h o m e s
on e a c h flo w e r r e c e p t a c le w a s r e m o v e d in th e fo r m o f d is tin c t n a rro w bands
ru n n in g p a r a lle l to th e lo n g a x is of th e flo w e r .

E v e r y p r e c a u tio n w a s m a d e

to p r e v e n t th e t w e e z e r s fr o m a c tu a l c o n ta c t w ith the e p id e r m is o f the r e ­
c e p t a c le s .
A n o th er s im ila r s e r i e s o f f lo w e r s had p o r tio n s o f th e tr ic h o m e m a t
to u ch ed w ith a b lo c k o f d ry ic e ( s o lid c a r b o n d io x id e ) to a p o in t th at th e tip s
o f th e t r ic h o m e s b e c a m e c u r le d and b row n in c o lo r .

T h e d r y ic e did not c o m e

in c o n ta c t w ith the e p id e r m is so th at o n ly in ju r y to th e o u te r p o r tio n o f th e
tr ic h o m e s o c c u r r e d .
T h e flo w e r s in e a c h c lu s t e r that w e r e not tr e a te d w e r e r e m o v e d and
the fr u itin g sp u r w a s p r o p e r ly ta g g e d a s to typ e o f tr e a tm e n t, sta g e o f b lo s s o m
d e v e lo p m e n t a t th e tim e o f tr e a tm e n t, and date o f tr e a tm e n t.
T h e fr u it s w e r e e x a m in e d w e e k ly fo r th e f i r s t s ix w e e k s and th en
m o n th ly t h e r e a fte r fo r s ig n s of r u s s e t d e v e lo p m e n t.

A fin a l c h e c k w a s m a d e

at fr u it m a tu r ity .
T he t r e e s w e r e sp r a y e d w ith tw o p ou nds o f ca p ta n p lu s on e pound o f
D D T p lu s one pound o f p a r a th io n p e r 100 g a llo n s o f sp r a y m ix tu r e fo r in s e c t and
d i s e a s e c o n tr o l th rou gh ou t th e g r o w in g s e a s o n .

41.

R ESU LTS

E x p e r im e n t 1.

C o n tr o lle d te m p e r a tu r e s tu d ie s to d e te r m in e th e r e la t io n ­

sh ip o f f r e e z in g a ir te m p e r a tu r e s and fu n g ic id e s a s a ff e c tin g fr u it r u s s e t in g .
T h e v a r io u s a ir te m p e r a tu r e s to w h ic h e a c h G old en D e lic io u s
t r e e on M a ilin g VII r o o t s t o c k s w a s e x p o s e d a r e g iv e n in T a b le I.

One tr e e

w a s e n c lo s e d d u rin g p e r io d s w h en a ir te m p e r a tu r e s o f 32° F o r lo w e r w e r e
e x p e c te d and the t r e e h e a te d to p r e v e n t e x p o s u r e to f r e e z in g a ir t e m p e r a ­
tu r e s w h ile the o th e r t r e e w a s e x p o s e d .
to u n a lte r e d e n v ir o n m e n ta l c o n d itio n s .

T h e th ir d t r e e w a s e n t ir e ly e x p o s e d
D u r in g the e a r ly m o r n in g h o u r s

o f M ay 16, 20, and 24 f r e e z in g te m p e r a tu r e s o f 3 1 . 7 ° , 31. 5° and 2 8 . 0 ° F
r e s p e c t iv e ly , w e r e r e c o r d e d on th e r m o m e te r s and th e r m o g r a p h s p la c e d
w ith in th e fr u itin g p o r tio n o f th e e x p o s e d t r e e s (T a b le I).

T h e t r e e s e le c t e d

fo r p r o te c tio n fro m t h e s e te m p e r a tu r e s w a s e n c lo s e d d u rin g the n ig h ts w hen
th e s e te m p e r a tu r e s o c c u r r e d and h e a te d w ith e le c t r ic a l s p a c e h e a t e r s .

The

a ir te m p e r a tu r e s o f th e e n c lo s e d t r e e did not drop b elow 32. 5 ° F (T a b le I).
T h e 28° F r e c o r d e d on M ay 24 la s t e d fo r a p p r o x im a te ly 45 m in u te s w h ile
the o th e r f r e e z in g te m p e r a tu r e s r e c o r d e d w e r e fo r s h o r te r d u r a tio n s.
R e c o r d s o f r u s s e t in g o f th e h a r v e s t e d fr u it w e r e o b ta in e d fro m
th e to ta l n u m b e r s o f fr u it s fro m e a c h h a lf - t r e e tr e a tm e n t w h ic h v a r ie d fro m
50 to 75 f r u it s .

T h e data o f th e fr u it r u s s e t in g r e s u lt in g fr o m th e tw o f a c ­

t o r s , fu n g ic id e s and f r e e z in g a ir te m p e r a tu r e s a r e p r e s e n t e d in T a b le II.

42.

T A BLE I
M in im u m A ir T e m p e r a t u r e s R e c o r d e d W ith in F r u itin g A r e a o f P r o te c te d and
E x p o s e d T r e e s o f G old en D e lic io u s - 1956

E xp osed T r e e s
D ate

M in im u m T e m p e r a tu r e
( D e g r e e s F)

P r o te c te d T r e e s
M in im u m T e m p e r a tu r e
(D e g r e e s F)

M ay 16 (Pink)

31. 7

32. 5

M ay 20 (E a r ly
B loom )

3 1 .5

34. 5

M ay 24 (E a r ly
P e ta l F a ll)

2 8 .0

33. 0

43.

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T h e c o m b in a tio n o f g ly o d in and f r e e z in g te m p e r a tu r e s r e s u lt e d
in 84. 5 p e r c e n t h e a v ily r u s s e t e d fr u it, w h ile on th e s a m e t r e e th e u s e o f
ca p ta n r e s u lt e d in o n ly 24. 4 p e r c e n t h e a v ily r u s s e t e d fr u it.

A ll o f th e r e ­

m a in in g fr u it fr o m th is t r e e , e x c e p t 2. 7 p e r c e n t o f th e fr u it f r e e o f r u s s e t ­
in g fr o m th e ca p ta n tr e a tm e n t, w e r e lig h tly r u s s e te d , 15. 5 p e r c e n t fo r the
g ly o d in tr e a tm e n t, and 72. 9 p e r c e n t fo r the ca p ta n tr e a tm e n t.

It sh o u ld be

r e - e m p h a s iz e d th at th e fr u it c l a s s i f i e d a s lig h tly r u s s e t e d w e r e a c c e p ta b le
fo r U. S. N o . 1 and F a n c y g r a d e s .
Of th e fr u it fr o m th e tr e e p r o te c te d fro m the f r e e z in g a ir t e m ­
p e r a t u r e s and r e c e iv in g th e g ly o d in tr e a tm e n t, 2 7 . 8 p e r c e n t w e r e h e a v ily
r u s s e t e d and 7 2 . 2 p e r c e n t w e r e lig h tly r u s s e t e d .

T h e cap tan tr e a te d p o r ­

tio n had no h e a v ily r u s s e t e d fr u it s , 43. 2 p e r c e n t w e r e o n ly lig h tly r u s s e te d ,
a n d 56. 8 p e r c e n t w e r e e n t ir e ly fr e e o f r u s s e tin g .
A r e la t iv e c o m p a r is o n o f the fr u it o f the tw o fu n g ic id e tr e a tm e n ts
fr o m t r e e s e x p o s e d to f r e e z in g te m p e r a tu r e s i s illu s t r a t e d in F ig u r e 3.
E x a m p le s o f fr u it s fr o m the p r o te c te d t r e e r e c e iv in g the s a m e tw o t r e a t ­
m e n ts a r e show n in F ig u r e 4.
T h e th ir d G o ld en D e lic io u s t r e e e x p o s e d to u n a lte r e d e n v ir o n ­
m e n ta l c o n d itio n s had in s u f fic ie n t fr u it s fo r e v a lu a tio n .
T h e r e c o r d s o f r u s s e t in g o f the h a r v e s te d fr u it o f the t h ir t y - y e a r o ld b e a r in g G o ld en D e lic io u s t r e e w h ich w a s d iv id e d in to tw o eq u a l h a lv e s ,

COLD

F ig u r e 3. A r e p r e s e n t a t iv e s a m p le o f a p p le s ta k en fr o m th e t r e e s e x p o s e d to
f r e e z in g a ir te m p e r a tu r e s and s p r a y e d w ith ca p ta n an d g ly o d in .

46.

PROTECTED

CAPTAN

G L Y O D IN

F ig u r e 4. A r e p r e s e n t a t iv e s a m p le o f a p p le s tak en fr o m the t r e e p r o te c te d
fro m f r e e z in g a ir te m p e r a tu r e s and s p r a y e d w ith cap tan and
g ly o d in .

o n e - h a lf s p r a y e d w ith g ly o d in and th e o th e r cap tan , a r e p r e s e n t e d a ls o , in
T a b le II.

T h e s e data a g r e e c l o s e l y w ith th e r e s u lt s o b ta in ed fro m the e x ­

p o s e d t r e e on M a ilin g VII r o o ts to c k s and r e c e iv in g the f r e e z in g a ir t e m p e r ­
a tu r e s (T a b le II).

In a s e v e n - b u s h e l sa m p le o f the h a r v e s te d fr u it fr o m the

p o r tio n o f th e t r e e tr e a te d w ith g ly o d in , 96. 5 p e r c e n t w e r e h e a v ily r u s s e t e d
and 3. 5 p e r c e n t w e r e lig h tly r u s s e te d , w h ile in a s e v e n - b u s h e l s a m p le fro m
th e c a p ta n tr e a tm e n t, o n ly 2 5. 5 p e r c e n t w e r e h e a v ily r u s s e t e d and 64. 6 p e r ­
c e n t lig h tly r u s s e t e d .

F u r th e r m o r e , the cap tan tr e a te d p o r tio n had 9. 9

p e r c e n t o f it s fr u it s f r e e of r u s s e t in g .
B e c a u se o f the c lo s e p r o x im ity o f th is t r e e to the c a g e t r e e s and
s in c e the e le v a t io n w a s n e a r ly id e n tic a l, it w a s a s s u m e d that f r e e z in g t e m ­
p e r a t u r e s o f v e r y c l o s e to 31. 7 ° F , 31. 5®F, and 2 8 . 0®F o c c u r r e d in th e
lo c a tio n o f th is t r e e on M ay 16, 20 and 24.
F r o m t h e s e data it i s d e m o n s tr a te d th at slig h t r u s s e t in g r e s u lt in g
fr o m th e o c c u r r e n c e o f f r e e z in g a ir te m p e r a tu r e s e a r ly in th e g r o w in g s e a ­
son , d u rin g o r n e a r b lo o m , m a y be in c r e a s e d to h e a v y r u s s e t in g o f a m a jo r
e c o n o m ic im p o r ta n c e by th e u s e o f c e r ta in p e s t ic id e c h e m ic a ls .

E x p e r im e n t 2.

F ie ld s tu d ie s to e v a lu a te the e f f e c t s o f fu n g ic id e s and f r e e z ­

in g a ir te m p e r a tu r e s on fr u it r u s s e t in g o f a p p le s .
T he fin d in g s o f th e tr e a tm e n ts th ir a m , captan , g ly o d in , and c a p ­
tan fo llo w e d by g ly o d in a ft e r f i r s t c o v e r , m a d e in the b lo c k o f s ix t e e n - y e a r -

o ld Jonathan, G o ld en D e lic io u s , and M cIn to sh a p p le t r e e s a r e g iv e n in
T a b le III.

In t h is stu d y, fiv e s in g le t r e e r e p lic a t io n s o f e a c h v a r ie t y w e r e

in c lu d e d in e a c h tr e a tm e n t.
A s in g le f r e e z in g te m p e r a tu r e o f 3 0 . 5 ° F o f a th ir ty -m in u te d u r a ­
tio n o c c u r r e d on M ay 16 w h en th e b lo s s o m s w e r e in th e e a r ly - p in k s ta g e .
T h e r e s u lt s fr o m e x a m in a tio n s o f the h a r v e s t e d fr u it, g iv e n in
T a b le III, r e v e a le d no s ig n ific a n t d if fe r e n c e s o f fr u it r u s s e t in g b e tw e en
tr e a tm e n ts .

T h e u s e o f ca p ta n th rou gh f i r s t c o v e r fo llo w e d by g ly o d in w a s

an a tte m p t to d e te r m in e if g ly o d in w o u ld c a u s e r u s s e t in g if u s e d on G o ld en
D e lic io u s a ft e r f ir s t c o v e r .

H o w e v er , a s no d if fe r e n c e s w e r e n o ted b e ­

tw e e n an y o f th e tr e a tm e n ts and th e u s e o f g ly o d in did c a u s e r u s s e t in g on
G o ld en D e lic io u s a s sh ow n in T a b le II, it w a s c o n je c tu r e d th at m eth o d o f
a p p lic a tio n o f the c h e m ic a ls p r o b a b ly p la y e d a v e r y im p o rta n t r o le a s to
w h e th e r o r not a p e s t ic id e c h e m ic a l w a s p h y to to x ic .
T h e r e s u lt s o f fr u it r u s s e t in g fr o m th e tr e a tm e n ts o f g ly o d in ,
th ir a m , cap tan , and fe r b a m , in B lo ck s I, II and III a t th e G raham E x p e r i­
m e n t S ta tio n a r e g iv e n in T a b le rV.

T h e r e w e r e no s ig n ific a n t d if fe r e n c e s

in h e a v y r u s s e t in g b e tw e e n tr e a tm e n ts fo r a n y o f th e v a r ie t ie s .

T h ere w ere

s ig n ific a n t d if f e r e n c e s , h o w e v e r , in lig h t r u s s e t in g fr o m th e v a r io u s s p r a y
tr e a tm e n ts in B lo ck I b e tw e e n th e u s e o f ca p ta n and fe r b a m on Jonathan, 11. 54
p e r c e n t fo r th e c a p ta n tr e a tm e n t a s c o m p a r e d to 5. 8 p e r c e n t fo r th e fe r b a m

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No sig n ific a n t d iffe r e n c e s between tr e a t m e n t s .

R u ssetin g of Jonathan, Golden D e lic io u s , and M cIntosh from the Use of Certain F u n g ic id e s after the
O ccu rren ce of 30. 5°F for 30 M in u tes. Graham E x p e rim e n t S tatio n , 1 9 5 6

49.

50.

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D iffe r e n c e s between trea tm en ts sig n ific a n t at the 5 p e rcen t le v e l.
Captan trea tm en t of Block I sig n ifica n tly higher than Captan trea tm en ts of Blocks II and III o f
the Jonathan v a r ie t y .

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tr e a tm e n t.

H o w e v er , it sh o u ld b e p o in te d ou t th a t th e p o r tio n o f B lock I

r e c e iv in g th e c a p ta n tr e a tm e n t w a s lo w e r in e le v a t io n than th a t p o r tio n
r e c e iv in g th e fe r b a m tr e a tm e n t o r th e o th e r b lo c k s in th is stu d y .

It i s

v e r y p r o b a b le th at in th is a r e a a lo w e r te m p e r a tu r e than th e r e c o r d e d
3 0 . 5* F c o u ld h a v e o c c u r r e d , w h ic h m a y a c co u n t fo r the h ig h e r am ou n t o f
r u s s e t in g o f th e Jonathan v a r ie t y in the ca p ta n tr e a tm e n t.

T h e am ou n t o f

both lig h t and h e a v y r u s s e t in g found on Jonathan in th e ca p ta n tr e a te d p o r ­
tio n o f B lock I w a s s ig n ific a n tly h ig h e r than th at found in th e ca p ta n tr e a te d
p o r tio n s o f B lo ck s II and III (T a b le IV).

E x p e r im e n t 3.

C o n tr o lle d te m p e r a tu r e s tu d ie s in 1957 to fu r th e r e v a lu a te

th e r e la t io n s h ip o f fu n g ic id e and f r e e z in g a ir te m p er a tu r e 's on fr u it r u s s e t in g
o f Jonathan and G o ld en D e lic io u s .
T h e data on fr u it r u s s e t in g o b ta in ed fr o m th e h a lf - t r e e tr e a tm e n ts
o f c a p ta n and g ly o d in on Jonathan e x p o s e d to d iffe r e n t a ir te m p e r a tu r e s n e a r
b lo o m a r e g iv e n in T a b le V .

V a r ia tio n s in fr u it r u s s e t in g on G o ld en D e l i ­

c io u s fr o m h a lf - t r e e tr e a tm e n ts o f g ly o d in a t fu ll s tr e n g th (one quart) and
o f g ly o d in a t h a lf - s t r e n g t h (on e pin t) p lu s o n e -fo u r th pound o f Phygon a r e
p r e s e n t e d in T a b le V .
T r e e n u m b e r o n e o f th e tw o v a r i e t i e s w a s e x p o s e d to o n ly one hour
o f a low o f 3 2 . 0 ° F fo r th e Jonathan and 3 1 . CTF fo r th e G old en D e lic io u s ,
w h ile t r e e n u m b e r tw o o f both v a r i e t i e s w a s e x p o s e d to a p e r io d o f fo u r

52.

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h o u r s and tw e n ty m in u te s o f f r e e z in g te m p e r a tu r e s r a n g in g fro m 2 9 . 5"F to
a m in im u m o f 2 7 . 5 ° F .

T r e e n u m b er th r e e w a s e x p o s e d on fo u r n ig h ts w hen

m in im u m a ir t e m p e r a tu r e s o f 32®F o r lo w e r w e r e r e c o r d e d .

The sta g e s of

f lo w e r an d fr u it d e v e lo p m e n t at th e tim e e a c h f r e e z in g a ir te m p e r a tu r e w a s
r e c o r d e d a r e g iv e n in T a b le V I.
A n ad d ed s in g le G o ld en D e lic io u s t r e e w a s s p r a y e d w ith ca p ta n and
w a s a ls o e x p o s e d to th e fo u r n ig h ts o f f r e e z in g a ir te m p e r a tu r e s g iv e n in
T a b le V I.
T h e p o r tio n s o f th e th r e e Jonathan t r e e s r e c e iv in g th e g ly o d in
tr e a tm e n t had a p r o g r e s s i v e l y in c r e a s in g am ou n t o f fr u it s e x h ib itin g h e a v y
r u s s e t in g , 2. 94 p e r c e n t, 7. 55 p e r c e n t, and 67. 07 p e r c e n t, r e s p e c t iv e ly ,
w h ic h c o r r e s p o n d e d w ith th e p r o g r e s s iv e ly in c r e a s in g a m o u n ts o f e x p o s u r e
to f r e e z in g a ir te m p e r a tu r e s n e a r b lo o m .

T h e p e r c e n ta g e o f fr u it s e x h ib it­

in g h e a v y r u s s e t in g r e c o r d e d fr o m th e u s e o f ca p ta n in c r e a s e d a ls o w ith
in c r e a s in g e x p o s u r e to f r e e z in g a ir te m p e r a tu r e s .

H o w e v er , th e p e r c e n t ­

a g e s o f r u s s e t e d fr u it fr o m th e ca p ta n tr e a tm e n ts w e r e s m a lle r than fro m
th e g ly o d in tr e a tm e n ts .

T o illu s t r a t e , fro m th e t r e e e x p o s e d to on e n igh t

o f 32. 0®F, o n ly 2. 44 p e r c e n t o f the fr u it fr o m th e ca p ta n tr e a tm e n t and
2. 94 p e r c e n t o f th e fr u it fr o m th e g ly o d in tr e a tm e n t w e r e h e a v ily r u s s e t e d .
T h e t r e e e x p o s e d to th e m in im u m te m p e r a tu r e o f 27. 5®F had 3. 92 p e r c e n t
o f th e fr u it fr o m th e c a p ta n tr e a tm e n t h e a v ily r u s s e t e d a s c o m p a r e d to 7. 55

Minimum

Air T e m p e r a tu r e s R ecorded Within the Fruiting Area of the T rees of Jonathan and G o ld e n
D e lic io u s Growing on Dwarfing R o o ts to c k s . East L a n sin g , 1 9 57

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55.

p e r c e n t fr o m th e g ly o d in tr e a tm e n t.

T h e g r e a t e s t d iffe r e n c e o c c u r r e d fr o m

th e e x p o s u r e to th e fo u r p e r io d s o f f r e e z in g a ir te m p e r a tu r e s , 15. 52 p e r ­
c e n t o f th e fr u it s w e r e h e a v ily r u s s e t e d w h en ca p ta n w a s u se d , a s c o m p a r e d
to 6 7 . 07 p e r c e n t o f h e a v ily r u s s e t e d fr u it fro m the u s e o f g ly o d in .
T h e r e w e r e no r u s s e t f r e e G o ld en D e lic io u s f r u it s h a r v e s t e d fr o m
an y o f th e sp r a y tr e a tm e n ts , T a b le V .

T h e tr e a tm e n ts , g ly o d in at one

q u a rt (fu ll str e n g th ) a s c o m p a r e d to g ly o d in at on e p in t (h a lf str e n g th ) p lu s
fo u r o u n c e s o f Phygon, w e r e d e s ig n e d w ith th e thought th at a r e d u c tio n in
c o n c e n tr a tio n o f g ly o d in fr o m on e q u art to one p in t and in c lu d e o n e -fo u r th
o f a pound o f P h ygon w ou ld d e c r e a s e th e am ou nt o f r u s s e t in g .

T h is did h o ld

tr u e to s o m e e x te n t a s th e am ou n t o f h e a v y r u s s e t in g fr o m th e u s e o f g ly o d in
a t o n e q u art w ith th e t r e e e x p o s e d to a 31* F m in im u m a ir te m p e r a tu r e fo r
o n e n ig h t w a s 96. 30 p e r c e n t a s c o m p a r e d to 4 0 . 0 0 p e r c e n t fo r th e g ly o d in P h ygon tr e a tm e n t.

H o w e v e r , th e r e w a s no c o m p a r a b le d e c r e a s e in h e a v y

r u s s e t in g on th e t r e e e x p o s e d to 2 7 . 5*F m in im u m te m p e r a tu r e e v e n w h e r e
th e r e d u c e d c o n c e n tr a tio n o f g ly o d in w a s u se d .

A n o th er o b s e r v a tio n o f in ­

t e r e s t , alth ou gh th e f r u it s e x p o s e d to th e 31. 0 ° F te m p e r a tu r e w e r e h e a v ily
r u s s e t e d , the r u s s e t in g w a s m u ch l e s s h e a v y than w hen th e e x p o s u r e w a s
27. 5 °F .

A ls o , th e h e a v ily r u s s e t e d fr u it fr o m th e g ly o d in -P h y g o n t r e a t ­

m e n t and e x p o s e d to 27. 5®F w e r e m u ch l e s s s e v e r e ly r u s s e t e d than th e
f r u it s fr o m th e g ly o d in tr e a te d p o r tio n o f th e t r e e .

T h is s a m e o b s e r v a tio n

w a s n o ted o f th e fr u it on th e t r e e e x p o s e d to the fo u r p e r io d s o f f r e e z in g
te m p e r a tu r e s a lth o u g h 100 p e r c e n t of the fr u it s fr o m both tr e a tm e n ts w e r e
h e a v ily r u s s e t e d .
T h e t r e e r e c e iv in g th e ca p ta n tr e a tm e n t fo llo w in g e x p o s u r e to fo u r
p e r io d s b elow 32* F had 96 p e r c e n t h e a v ily r u s s e t e d fr u it and 4 p e r c e n t
lig h tly r u s s e t e d .

T h is d o e s not c o m p a r e w ith 24. 4 p e r c e n t o f th e fr u it

h e a v ily r u s s e t e d and 7 2. 9 p e r c e n t lig h tly r u s s e t e d r e c o r d e d fo r th e s a m e
tr e a tm e n t in 1956.

H o w e v er , o n ly th r e e p e r io d s o f a ir te m p e r a tu r e b elow

3 2 ° F w e r e r e c o r d e d in 1956 (T a b le I) and th e s e w e r e l e s s s e v e r e than the
fo u r m in im u m te m p e r a tu r e s r e c o r d e d in 1957 (T a b le VI).
T h e ty p e s o f lig h t and h e a v y r u s s e t in g that o c c u r r e d on the Jonathan
v a r ie t y in 1957 a r e illu s t r a t e d in F ig u r e 5.

T he r u s s e t p a tte r n on G o ld en

D e lic io u s in 1957 w a s s im ila r to that o c c u r r in g in 1956, and p r e s e n t e d in
F ig u r e 3.

E x p e r im e n t 4.

F u r th e r f ie ld s tu d ie s to d e te r m in e th e e f f e c t s o f fu n g ic id e s

and f r e e z in g a ir te m p e r a tu r e s on fr u it r u s s e t in g .
T h e tr e a tm e n ts a t th e G raham S ta tio n w e r e m a d e o n ly in B lo ck s I,
II and III and o n ly the v a r i e t i e s M cIn to sh and Jonathan w e r e e v a lu a te d fo r
fr u it r u s s e t in g in 1957.

T h e fu n g ic id e s stu d ie d w e r e th ir a m , g ly o d in , and

w e tta b le su lfu r w ith ca p ta n b e in g u s e d in e a c h b lo c k a s a c o n tr o l tr e a tm e n t.

57.

F ig u r e 5.

S a m p le s o f r u s s e t e d Jonathan a p p le s o c c u r r in g in E a s t L a n s in g
s tu d ie s , 1957. T h e fr u it on th e r ig h t i s h e a v ily r u s s e te d , and the
fr u it on th e le ft i s lig h tly r u s s e t e d .

58.

T h e data fr o m fiv e o n e -b u s h e l s a m p le s o f th e r e p lic a te d t r e e s a r e g iv e n
in T a b le VII.
D u r in g th e e a r ly m o r n in g h o u r s o f M ay 3, w h en th e f lo w e r s w e r e
at e a r ly pink, a m in im u m o f 31. 5° F w a s r e c o r d e d n e a r th e t e s t p lo t s .
T w o d a y s la te r , w h en th e b lo s s o m s w e r e at fu ll pink, a m in im u m t e m p e r ­
a tu r e o f 31. 0 ° F w a s e x p e r ie n c e d .

D u r in g p e ta l f a ll on M ay 16, a th ir d

m in im u m te m p e r a tu r e o f 31. 5° F w a s r e c o r d e d .
At h a r v e s t tim e , w hen th e s a m p le s w e r e e x a m in e d , m u ch m o r e
r u s s e t in g w a s o b s e r v e d than w a s p r e s e n t th e p r e v io u s y e a r on th e Jonathan
and M cIn to sh v a r i e t i e s (T a b le VIII).
T h e q u an tity o f h e a v ily r u s s e t e d Jonathan a p p le s h a r v e s t e d fr o m
th e ca p ta n tr e a tm e n t in B lock I w a s s ig n ific a n tly h ig h e r , 2 1 . 60 p e r c e n t,
than th e 12. 40 p e r c e n t fo r th e su lfu r tr e a tm e n t.

H o w e v e r , th e p lo t r e c e i v ­

in g th e cap tan tr e a tm e n t w a s at a lo w e r e le v a t io n than th e o th e r t e s t p lo t s .
T h e r e fo r e , it i s r e a s o n a b le to a s s u m e th at lo w e r te m p e r a tu r e s m a y h a v e
o c c u r r e d in th is p lo t than w a s e x p e r ie n c e d in th e o th e r tr e a tm e n ts w h ich
c o u ld p e r h a p s a c co u n t fo r th is h ig h e r p e r c e n t a g e o f h e a v ily r u s s e t e d fr u it s
(2 1 . 6 0 p e r c e n t) than o c c u r r e d from the u s e o f ca p ta n in the o th e r b lo c k s ,
17. 30 p e r c e n t and 12. 10 p e r c e n t .
T h e u s e of g ly o d in on Jonathan r e s u lt e d in 2 9 . 50 p e r c e n t o f th e
fr u it h e a v ily r u s s e t e d at h a r v e s t tim e , a s c o m p a r e d to 17. 30 p e r c e n t fo r

59.

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* D ifferen ce between tr e a tm e n ts sig n ific a n t at the 5 p ercen t le v e l.
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th e c a p ta n tr e a tm e n t.

T h is d if fe r e n c e i s s ig n ific a n t.

It sh o u ld b e n o ted

th a t th e d if f e r e n c e s in a m o u n t o f h e a v y r u s s e t in g in B lock III, 12. 10 p e r ­
c e n t fo r th e ca p ta n tr e a tm e n t, a s c o m p a r e d to 1 8 . 00 p e r c e n t fr o m th e u s e
o f th ir a m , i s a ls o s ig n ific a n t.
No s ig n ific a n t d if f e r e n c e s in e it h e r lig h t o r h e a v y r u s s e t in g w e r e
found b e tw e e n tr e a tm e n ts m a d e on th e M cIn to sh v a r ie t y in 1 9 5 7 .
S in c e th e fu n g ic id e s u s e d th ro u g h f i r s t c o v e r w e r e th e s a m e fo r
th e tr e a tm e n ts in th e y e a r s 1956 and 1957 and th e m eth o d o f a p p lic a tio n w a s
th e s a m e , th e data o f fr u it r u s s e t in g w e r e e v a lu a te d to d e te r m in e if th e
e f f e c t s o f f r e e z in g a ir te m p e r a tu r e s w e r e s ig n ific a n tly d iffe r e n t fo r the
tw o s e a s o n s u n d er f ie ld c o n d itio n s .

A s in g le f r e e z in g te m p e r a tu r e o f

3 0 . 5 ° F o c c u r r e d a t e a r ly p in k in 1956, w h e r e a s th r e e p e r io d s o f t e m p e r a ­
tu r e s b elo w 3 2 ° F w e r e r e c o r d e d in 1 9 5 7 .
In e v e r y c a s e th e p e r c e n t a g e o f both lig h t and h e a v y r u s s e t e d
f r u it s in 1957 w a s h ig h e r than in 1956, w ith th e s a m e tr e a tm e n t (T a b le VIII)
an d th e d if f e r e n c e s w e r e h ig h ly s ig n ific a n t, e x c e p t fo r th e h e a v y r u s s e t in g
o f th e th ir a m tr e a tm e n t.

H e r e th e v a r ia tio n b e tw e e n t r e e s w a s g r e a t e r

th an th e d if fe r e n c e b e tw e e n th e tr e a tm e n ts m a d e in 1956 and 1957 so no
s ig n if ic a n c e r e s u lt e d e v e n though th e a v e r a g e o f h e a v y r u s s e t in g in 1957
w a s h ig h e r th an in 1 9 5 6 .

62.

I n te r a c tio n o f th e u s e o f c e r ta in fu n g ic id e c h e m ic a ls and o c c u r r e n c e o f
f r e e z in g a ir te m p e r a tu r e s n e a r and d u rin g b lo o m on fr u it r u s s e t in g of
G o ld en D e lic io u s , Jonathan and M cIn to sh a p p le s .

G r a p h ic p r e s e n t a t io n s o f th e in te r a c tio n r e s u lt in g fr o m th e u s e o f
c e r t a in fu n g ic id e s and th e o c c u r r e n c e o f f r e e z in g a ir te m p e r a tu r e s (32° F
and b e lo w ) n e a r and d u rin g b loom a r e g iv e n in F ig u r e s 6 to 10.
G o ld en D e lic io u s :

In 1956 a t th e G rah am E x p e r im e n t S ta tio n , a

s in g le r e c o r d e d m in im u m a ir te m p e r a tu r e o f 3 0 . 5*F o c c u r r e d w hen the
b l o s s o m s w e r e in th e e a r ly p in k s ta g e .

T h e fu n g ic id e s , cap tan , th ir a m ,

g ly o d in and ca p ta n fo llo w e d by g ly o d in a fte r f i r s t c o v e r , w e r e u s e d a s
th e tr e a tm e n t s p r a y s w ith in s e c t ic i d e s u s e d u n ifo r m ly th ro u g h o u t a ll
tr e a tm e n ts.

No s ig n ific a n t d if f e r e n c e s w e r e o b s e r v e d b e tw e e n n u m b e r s

o f r u s s e t e d fr u it s h a r v e s t e d fro m th e t r e e s o f th e fu n g ic id e tr e a tm e n ts
(F ig u r e 6).

In th is stu d y, th e s p r a y m a t e r ia ls w e r e a p p lie d w ith an a ir

b la s t a tta ch m en t m o u n ted on a h ig h p r e s s u r e s p r a y e r .
D u r in g th e s a m e y e a r in E a s t L a n s in g w h e r e g ly o d in and ca p ta n
w e r e u s e d a s h a lf - t r e e tr e a tm e n ts on th e s a m e tr e e and th e t r e e w a s p r o ­
t e c t e d fro m f r e e z in g a ir te m p e r a tu r e s , no h e a v y r u s s e t in g o c c u r r e d fr o m
the ca p ta n tr e a tm e n t, but 2 7 . 8 p e r c e n t of the fr u it w a s h e a v ily r u s e t e d
fr o m th e g ly o d in tr e a tm e n t.
a d ju s ta b le n o z z le hand gun.

In th is c a s e , a p p lic a tio n s w e r e m a d e w ith an

63.

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64.

T h e am ou n t o f fr u it r u s s e t in g on G o ld en D e lic io u s in the c o n tr o lle d
te m p e r a tu r e s tu d ie s and in th e fie ld s tu d ie s c a r r ie d on in E a s t L a n s in g in
1956 u s in g the s a m e sp r a y c h e m ic a ls i s v e r y s im ila r ( F ig u r e s 6 and 7).
It i s a s s u m e d th at the r e a s o n fo r v e r y lit t le r u s s e t in g o f G o ld en D e lic io u s
fr o m th e u s e o f g ly o d in in p lo t s at th e G ra h a m E x p e r im e n t S ta tio n w a s r e ­
la te d to the m eth o d o f a p p lic a tio n a s w e ll a s f r e e z in g a ir t e m p e r a tu r e s .
It is a p p a re n t that m e c h a n ic a l in ju r y to th e e p id e r m a l t is s u e fr o m gun s p r a y ­
in g m a k e s it p o s s ib le fo r th e g ly o d in o r a co m p o n en t o f g ly o d in to p a s s
th rou gh th e e p id e r m a l la y e r and c o n ta c t th e o u te r c e l l s o f c o r t ic a l t is s u e .
T h is , in turn, m a y c a u s e p r o lif e r a tio n o f the o u te r c o r t ic a l c e l l s r u p tu r in g
the e p id e r m a l la y e r (F ig u r e 25).

T h e e p id e r m a l c e l l s a p p a r e n tly w e r e not

in ju r ed from a ir b la s t a p p lic a tio n s and th u s the e p id e r m a l c e l l s fu n c tio n e d
a s a p r o t e c t iv e la y e r a g a in s t th e a b s o r p tio n o f g ly o d in .
T h e r u s s e t in g o f G old en D e lic io u s a p p le s in 1957 w a s v e r y s e v e r e
(F ig u r e 7).

H o w e v er , a r e d u c tio n o f r u s s e t in g by d e c r e a s in g th e c o n c e n t r a ­

tio n o f g ly o d in in th e s p r a y m ix tu r e w a s o b s e r v e d w h en th e t r e e w a s e x ­
p o s e d to the 31.C T F m in im u m te m p e r a tu r e .

A ls o , th e e x p o s u r e o f 2 7 , 5° F

did not a p p ea r to c a u s e any d iffe r e n c e in am ou n t o f r u s s e t in g b e tw e e n t r e a t ­
m e n ts .

T h e fr u it s fro m th e g ly o d in and r e d u c e d s tr e n g th g ly o d in p lu s

P hygon tr e a tm e n ts fo llo w in g e x p o s u r e to fo u r p e r io d s o f f r e e z in g t e m p e r a ­
tu r e s w e r e 100 p e r c e n t s e v e r e ly r u s s e t e d .

E v en th e ca p ta n tr e a tm e n t

9N I± 3S S n a
-LN30a3d

66.

e x p o s e d to t h e s e fo u r p e r io d s o f f r e e z in g a ir te m p e r a tu r e s had 96 p e r c e n t
h e a v ily r u s s e t e d fr u it.

It w a s o b s e r v e d in a ll tr e a tm e n ts , h o w e v e r , that

th e h e a v ily r u s s e t e d fr u it fr o m th e r e d u c e d s tr e n g th g ly o d in p lu s Phygon
tr e a tm e n t w e r e l e s s s e v e r e l y r u s s e t e d than th e fr u it r e c e iv in g fu ll s tr e n g th
g ly o d in .
In c o m p a r in g the g ly o d in tr e a tm e n ts in th e c o n tr o lle d te m p e r a tu r e
s tu d ie s o f 1956 w ith th e s a m e tr e a tm e n t in 1957 and w ith th e tw o ca p ta n
t r e a tm e n ts (F ig u r e 7), it is v e r y e v id e n t th at th e am ou n t o f h e a v y r u s s e t ­
in g w a s g r e a t e r in 1957 than in 1956.

A ls o , th e r e c o r d e d m in im u m t e m ­

p e r a t u r e s in 1957 w e r e lo w e r , 2 7. 5 °, 30. 5 °, 31. 5® and 30. 5 ° F th an in
1956, 31. 7% 31. 5° and 28° F (T a b le s I and VI), and th ey o c c u r r e d p r io r
to b loom in 1957 (T a b le VI), w h e r e a s th e 2 8 . 0 ° F low r e c o r d e d in 1956 w a s
a fte r b lo o m (T a b le I).
Jonathan:

A c o m p a r is o n o f the fie ld s tu d ie s w ith th o s e c o n d u cted

u n d er c o n tr o lle d c o n d itio n s ( F ig u r e s 8 and 9) sh o w ed that a s th e h o u r s o f
f r e e z in g te m p e r a tu r e s in c r e a s e d , th e a m o u n t of r u s s e t in g in c r e a s e d c o r r e s ­
p o n d in g ly .

N e v e r t h e le s s , the a m o u n t o f h e a v y fr u it r u s s e t in g o b s e r v e d in

1957 in both th e fie ld s tu d ie s and th o s e u n d er c o n tr o lle d c o n d itio n s w h en
f r e e z in g te m p e r a tu r e s o c c u r r e d n e a r b lo o m w a s c o n s id e r a b ly l e s s fr o m
th e u s e o f ca p ta n than fro m th e u s e of g ly o d in .
A g r e a t e r p e r c e n ta g e of r u s s e t e d fr u its r e s u lt e d u n d er th e m o r e

67.

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s e v e r e f r e e z in g te m p e r a tu r e s of th e c o n tr o lle d s tu d ie s than w a s o b s e r v e d
in th e f ie ld s t u d ie s .

H e r e a g a in , it sh o u ld a ls o be n o ted th at the fie ld a p ­

p lic a t io n s w e r e m a d e w ith an a i r - b l a s t s p r a y e r , w h ile th e a p p lic a tio n s in
th e c o n tr o lle d te m p e r a tu r e s tu d ie s w e r e m a d e w ith an a d ju s ta b le n o z z le
hand gun.
M cIn to sh :

F r u it r u s s e t in g , in g e n e r a l, on th e M cIn to sh v a r ie t y

(F ig u r e 10) w a s l e s s than on the o th e r v a r i e t ie s fo r the s a m e fu n g ic id e
t r e a tm e n ts and w e a th e r c o n d itio n s , and no r e s u lt s w e r e s ig n ific a n tly d if ­
fe r e n t.

H o w e v er , it w a s o b s e r v e d that th e la r g e r n u m b er o f f r e e z in g a ir

te m p e r a tu r e p e r io d s n e a r fu ll b loo m in 1957 in c r e a s e d th e am ou n t o f
both lig h t and h e a v y r u s s e t in g in a ll tr e a tm e n ts o v e r th at found in 1956
(T a b le VIII).

70.

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71.

H is to lo g ic a l I n v e s tig a tio n s

E x p e r im e n t 5.

H is t o lo g ic a l in v e s tig a tio n s to stu d y th e d e v e lo p m e n t o f the

p r o t e c t iv e la y e r s o f G old en D e lic io u s , Jonathan, and M cIn to sh w ith s p e c ia l
a tte n tio n g iv e n to th e c u t ic le and to stu d y th e o r ig in and g ro w th o f r u s s e t e d
t i s s u e s o f the fr u it.
T he r e c e p ta c u la r p o r tio n o f f lo w e r s b e fo r e b lo o m and th e d e v e lo p ­
in g f r u it s a ft e r b loom o f G o ld en D e lic io u s , Jonathan and M cIn to sh a p p le s
w e r e e x a m in e d m ic r o s c o p ic a lly to stu d y th e d e v e lo p m e n t o f th e e p id e r m a l
la y e r and th e fo r m a tio n o f c u t ic le .

S e r ia l s e c t io n s o f k ille d and fix e d

m a t e r ia l w e r e e x a m in e d fro m the s t a g e s o f fu ll b lo o m to m a tu r ity .

Sec­

tio n s o f fr o z e n m a t e r ia l w e r e e x a m in e d fro m th e p r e - p in k s ta g e to p e ta l
fa ll.

T h e d e v e lo p m e n t o f th e p r o t e c t iv e la y e r s o f G o ld en D e lic io u s is

illu s t r a t e d in F ig u r e s 11 th rou gh 17.

A s no a p p a re n t d if f e r e n c e s c o u ld be

o b s e r v e d b e tw e e n th e d e v e lo p in g c e l l s and t i s s u e s o f th e th r e e v a r ie t ie s
u n til a p p r o x im a te ly 30 d a y s a fte r fu ll b lo o m , th e illu s t r a t io n s o f th e G o ld en
D e lic io u s , F ig u r e s 11 th ro u g h 15, r e p r e s e n t a ls o th e M cIn to sh and Jonathan.
A s th e f lo w e r s e m e r g e fro m the w in te r bud and w hen th e flo r a l
r e c e p t a c le b e c a m e f i r s t e x p o s e d to e n v ir o n m e n ta l c o n d itio n s a t the tim e o f
p r e -p in k , th e r e c e p t a c le w a s c o v e r e d w ith w hat a p p e a r s to be a d e n s e m a t
o f t r ic h o m e s .

M ic r o s c o p ic e x a m in a tio n o f th e th r e e v a r i e t i e s r e v e a le d that

Figure 11. Atransverse-section of the floral receptacle o
fG
olden Delicious at full bloom sectioned
w
ith the freezing microtome at six microns and stained w
ith Sudan IV(XI750).
72 .

F ig u r e 12. T r a n s v e r s e - s e c t io n o f the flo w e r r e c e p t a c le o f G old en
D e lic io u s at fu ll bloom sh o w in g a b s e n c e o f c u tic le on the fr u it
s u r fa c e (X 350).

F ig u r e 13. T r a n s v e r s e - s e c t io n o f th e fr u it o f G old en D e lic io u s at
p e ta l fa ll sh o w in g the e a r l i e s t d e p o sit o f c u tic le o c c u r r in g
at the b a se o f the tr ic h o m e . T h e o u te r c o r t ic a l c e l l s a r e
s ta r tin g to show th ic k e n in g o f the c e ll w a lls (X350)^

F ig u r e 14. T r a n s v e r s e - s e c t io n o f the fr u it o f G old en D e lic io u s , s e v e n
d a y s a fte r p e ta l fa ll (f ir s t c o v e r ) sh o w in g d e p o s it o f c u t ic le at
the b a s e of the tr ic h o m e and a c o m p le te c u tic le on the fr u it
s u r fa c e (X 350).

73.

F ig u r e 15. T r a n s v e r s e - s e c t io n o f th e fr u it o f G old en D e lic io u s , th r e e
■weeks a fte r fu ll b loom (se c o n d c o v e r ) sh o w in g th e r e s u lt s o f
the slo u g h in g o ff o f a tr ic h o m e and th e c o m p le t e n e s s o f a c u tic le
on the fr u it s u r fa c e (X 350).

F ig u r e 16. T r a n s v e r s e - s e c t io n o f the fr u it o f G o ld en D e lic io u s , tw o
m o n th s a fte r fu ll bloom sh o w in g s e p a r a tio n o f th e e p id e r m a l
c e l l s and the fo r m a tio n o f c u tic u la r p e g s (X 350).

F ig u r e 17. T r a n s v e r s e - s e c t io n o f the fr u it o f G o ld en D e lic io u s a t
m a tu r ity sh o w in g ir r e g u la r c u tic le , in d is tin g u is h a b le e p id e r m a l
la y e r and c e ll se p a r a tio n o f o u ter c o r t ic a l c e l l s w ith c u tic le
f illin g t h e s e gap s (X 350).

75.

th e a c tu a l n u m b e r s o f m o d ifie d e p id e r m a l c e l l s fo r m in g the tr ic h o m e s w e r e
r e l a t iv e l y fe w .

B e c a u se th e y w e r e v e r y lo n g and en ta n g led , t h e s e lo n g u n i­

c e llu la r t r ic h o m e s fo r m e d a m a tte d m a s s th at c o v e r e d the r e c e p t a c le .

T he

e p id e r m a l la y e r a t th is s ta g e c o n s is t e d o f r a d ia lly e lo n g a te d , d e n s e ly p a ck ed ,
b r ic k -s h a p e d c e l l s .

T h e d im e n s io n s o f th e s e c e l l s fo r th e th r e e v a r ie t ie s

w e r e 3. 6 to 5. 4 m ic r o n s ta n g e n tia lly , and 7. 2 to 10. 8 m ic r o n s r a d ia lly .
At th e tim e of p r e -p in k , no c u tic le w a s e v id e n t on the o u te r s u r ­
fa c e o f the e p id e r m a l c e ll w a lls .

H o w ev er, e x a m in a tio n o f the Sudan IV

s ta in e d s e c t io n s o f f r o z e n m a t e r ia l r e v e a le d that s o m e o r a n g e sta in w a s
p r e s e n t w ith in the o u te r c e l l w a ll o f s o m e e p id e r m a l c e l l s .

A c c o r d in g to

J o h an sen (27), w a x e s and o th e r fa tty m a t e r ia ls s ta in a dull r e d w ith Sudan
IV.

T h e s ta in e d p o r tio n s e e m e d to be a r r a n g e d a s r a d ia l bands w ith in the

c e l l w a ll o f th e e x p o s e d p o r tio n o f th e c e l l .
a t a ll.

M any c e l l s w e r e not s ta in e d

T h e r e s e e m e d to be no s p e c if ic p a tte r n a s to w h e r e the c e l l s that

w e r e r e c e p t iv e to s ta in w e r e lo c a te d on th e flo w e r r e c e p t a c le .

T h e Jonathan

flo r a l r e c e p t a c le s e x h ib ite d th e d e e p e s t sta in in th e e p id e r m a l c e ll w a lls .
T h e e p id e r m a l c e l l s o f th e M cIn to sh s ta in e d so m ew h a t lig h te r .

T h e G old en

D e lic io u s w a s o b s e r v e d to h a v e o n ly an o c c a s io n a l e x p o s e d w a ll o f an
e p id e r m a l c e l l w ith a s lig h t o r a n g e tin g e .
A s th e f lo w e r s c o n tin u e d to d e v e lo p to fu ll b lo o m , the in te n s ity o f
th e Sudan IV sta in in c r e a s e d fo r a ll v a r ie t i e s , but co n tin u ed to be w ith in the

76.

e x p o s e d 'wall o f e p id e r m a l c e l l s .

A t th e p in k s ta g e th e o r a n g e sta in a p p ea r e d

to be m o s t in te n s e in th e e p id e r m a l c e ll w a lls o f th e G old en D e lic io u s .
N e a r ly a ll o f th e o u te r w a lls o f th e e p id e r m a l la y e r o f th e th r e e v a r ie t ie s
sh o w ed s o m e d e g r e e o f in t e n s it y o f o r a n g e sta in , alth o u g h s o m e a r e a s in
the e x p o s e d w a ll o f s o m e c e l l s w e r e not s ta in e d .
T h e in t e n s it y o f o r a n g e s ta in co n tin u ed to in c r e a s e w ith in the e x ­
p o s e d c e l l w a lls o f th e f lo r a l r e c e p t a c le a s the flo w e r s co n tin u ed to a p p roach
fu ll b lo o m , and at fu ll b lo o m , a ll th e e x p o s e d c e ll w a lls o f the r e c e p ta c le of
the f lo w e r s o f th e th r e e v a r i e t i e s w e r e c le a r ly s ta in e d by the Sudan IV.

A

deep o r a n g e s ta in w a s o b s e r v e d at th e b a s e o f the tr ic h o m e s e x te n d in g fro m
th e e p id e r m a l la y e r a s illu s t r a t e d by F ig u r e 11.

Upon c lo s e e x a m in a tio n ,

s o m e e x te r n a lly s ta in e d m a t e r ia l co u ld be o b s e r v e d a c c u m u la tin g in the
c a v it ie s b e tw e e n c e r ta in t r ic h o m e s and th e a d jo in in g e p id e r m a l c e l l s .

T h is

w a s e s p e c ia lly tr u e w ith th e M cIn to sh v a r ie ty , w h ile o n ly an o c c a s io n a l
d e p o s it o f th is n a tu r e w a s o b s e r v e d fo r th e Jonathan and G o ld en D e lic io u s
v a r ie t ie s .

A n o c c a s io n a l tr ic h o m e o f the M cIn to sh w a s d is lo d g e d d u rin g

the s e c tio n in g p r o c e s s and in e v e r y c a s e , a s m a ll, v e r y thin, h e a v ily sta in e d
film w a s a tta c h e d to th e b a s e o f th e tr ic h o m e , in d ic a tin g that an e x te r n a l
d e p o s it o f c u t ic le w a s p r e s e n t .

No s im ila r d e p o s it w a s o b s e r v e d on the d i s ­

lo d g e d t r ic h o m e s o f th e v a r i e t i e s Jonathan and G old en D e lic io u s .
No e x te r n a l c u t ic le c o u ld be o b s e r v e d on th e s e r i a l s e c t io n s o f

77.

p e r m a n e n t p r e p a r a tio n s (F ig u r e 12) m a d e o f th e th r e e v a r i e t ie s a t th is
s ta g e .

T h is c o u ld be due to th e p o s s ib le s o lu b ility o f th is e a r ly d e p o s it

o f c u t ic le in th e m a t e r ia ls u s e d fo r p r e p a r in g th e s e p e r m a n e n t s e c tio n s ,
su c h a s th e e th y l a lc o h o l and x y le n e .

A p p le c u tic le in la t e r s t a g e s h a s

b een c o n s id e r e d to be in s o lu b le in m o s t o r g a n ic s o lv e n ts (7).
A t p e ta l f a ll, th r e e to s ix d a y s a fte r fu ll b lo o m , d ep en d in g upon
the v a r ie t y , a d is t in c t c u t ic le w a s e v id e n t at th e b a s e o f the e p id e r m a l
h a ir s (F ig u r e 13) o f p r e p a r e d s e c t io n s o f th e fr u it.

H o w e v er , no c u tic le

c o u ld be d e te c te d on th e s u r fa c e o f th e e p id e r m a l c e l l s e x c e p t th at d e ­
p o s ite d a ro u n d th e b a s e o f th e t r ic h o m e s .

E x a m in a tio n o f th e fr o z e n

m a t e r ia l s ta in e d w ith Sudan IV r e v e a le d that a c u tic le w a s p r e s e n t in
o th e r a r e a s a s w e ll a s th e b a s e o f th e t r ic h o m e s .

T h e d e p o s it w a s not

c o n tin u o u s o v e r th e e n tir e s u r fa c e o f the fr u it and w a s l e s s than o n e m ic r o n
th ic k in th e a r e a o f th e h e a v ie s t d e p o s it.
T h e d e n s e m a t o f tr ic h o m e s w a s s t i ll p r e s e n t on the fr u it a t th e
p e ta l f a ll s ta g e .

T h e e p id e r m a l la y e r o f a ll th r e e v a r ie t ie s s t il l c o n s is t e d

o f tig h tly p a c k e d , r a d ia lly e lo n g a te d c e l l s w ith v e r y d e n s e c y to p la s m .

At

th is s ta g e th e o u te r c o r t ic a l la y e r o f c e l l s a p p e a r e d to show s ig n s o f d if­
fe r e n tia tin g in to a t is s u e so m e w h a t d iffe r e n t fr o m th e o th e r c o r t ic a l c e l l s
(F ig u r e 1 3 ).

T h e c e l l w a lls o f th is la y e r a ls o a p p e a r e d th ic k e r than in n er

c o r t ic a l c e l l s and s o m e p e r ic lin a l d iv is io n o f c e l l s w a s e v id e n t.

A s th e fr u it c o n tin u e d to d e v e lo p , m o r e c u t ic le w a s d e p o s ite d on
th e s u r fa c e o f th e e p id e r m a l la y e r and by s e v e n d a y s a fte r p e ta l fa ll,
c o n s id e r e d a s th e tim e o f f i r s t c o v e r , the d e p o sit o f c u tic le w a s c o m p le te
and th e o u te r w a lls o f th e e p id e r m a l c e l l s w e r e c o v e r e d w ith a w axy c o a t ­
in g (F ig u r e 1 4 ).

T h is w a s tr u e o f th e Jonathan, G old en D e lic io u s and

M cIn to sh v a r i e t i e s .

T h e c u tic le w a s o b s e r v e d to have f ille d in around the

b a s e o f th e tr ic h o m e s so that the tr ic h o m e s a p p ea r to be s e p a r a te d from
the e p id e r m a l la y e r .

T he e p id e r m a l c e l l s w e r e s im ila r to the d e s c r ip tio n

g iv e n fo r p e ta l fa ll and th e o u ter c o r t ic a l c e l l s had b e c o m e in c r e a s in g ly
d e n s e , th e c e l l w a lls had th ick en ed , and th e r e w a s e v id e n c e o f both a n tic lin a l
and p e r ic lin a l d iv is io n s .
T h r e e w e e k s a fte r fu ll b lo o m , m a n y o f th e tr ic h o m e s had s lo u g h e d
o ff due to th e d e p o s it o f c u t ic le a t th e ir b a s e s (F ig u r e 15).

T h e e p id e r m a l

la y e r of th e fr u it s o f a ll th r e e v a r i e t i e s w a s s im ila r to th e d e s c r ip tio n
p r e v io u s ly g iv e n , ( illu s t r a t e d by F ig u r e s 15, 19 and 22) and no d if fe r e n c e s
co u ld be o b s e r v e d b e tw e e n v a r ie t ie s .

T h e d is tin g u is h a b le o u te r c o r t ic a l

la y e r had in c r e a s e d on e to th r e e c e l l s in th ic k n e s s and the c e ll c y to p la sm
r e m a in e d q u ite d e n s e and th e c e l l w a lls th ick .
At a p p r o x im a te ly 30 d a y s a ft e r fu ll b loom , the c e l l s of the e p id e r m a l
la y e r of th e G o ld en D e lic io u s a p p e a r e d to be s e p a r a tin g w ith c u tic u la r p e g s
o r e x te n s io n s d e v e lo p in g b e tw e e n th e a n tic lin a l c e l l w a lls .

A s th e fr u it

79.

c o n tin u e d to g ro w , th e s e p a r a t io n s b e c a m e m o r e e v id e n t (F ig u r e 16), and
by m a tu r ity m a n y c e l l s o r g r o u p s o f c e l l s a p p e a r e d in c r o s s - s e c t i o n to be
c o m p le t e ly s u s p e n d e d in th e c u t ic le w ith the c u tic le in c o n ta c t w ith the
s u b - e p id e r m a l c e l l s o f the o u te r c o r t e x (F ig u r e 17).
By c o m p a r is o n , th e e p id e r m a l c e l l s of the M cIn to sh a p p ea r e d i s o d ia m e tr ic u n til about s ix w e e k s a ft e r fu ll b lo o m , w hen th ey w e r e found to
be s tr e tc h e d and fla tte n e d in c r o s s - s e c t i o n (F ig u r e 19).

H o w ev er, at

m a tu r ity (F ig u r e 20) th e c e l l s o f the e p id e r m a l la y e r w e r e s t ill in ta ct and
the la y e r c o m p le te , e v e n though s o m e c u tic u la r fla n g e s w e r e o b s e r v e d to
ex te n d p a r t ia lly b e tw e e n th e a n tic lin a l c e ll w a lls o f so m e e p id e r m a l c e l l s .
T he o u te r c o r t ic a l c e l l s of th e M cIn to sh fr u it w e r e v e r y d e n se and had v e r y
th ick c e l l w a lls .

T h e n u m b er o f c e l l s in th is la y e r v a r ie d c o n s id e r a b ly

fro m one a r e a to a n o th e r.
T h e d e v e lo p m e n t o f th e e p id e r m a l la y e r o f Jonathan w a s found to
be m o r e s im ila r to the G o ld en D e lic io u s than th e M cIn tosh , but the p r e s e n c e
o f c u tic le w ith in and b elow th is c e l l la y e r w a s not a s e x t e n s iv e a s fo r the
G old en D e lic io u s ( F ig u r e s 22 and 2 3 ).

T h e o u te r c o r t ic a l la y e r o f c e l l s w a s

m o r e in ta c t than in G o ld en D e lic io u s , s im il a r to th e M cIn to sh .

T h e o u te r

c o r t ic a l c e l l s w e r e s m a ll, v e r y d e n s e and th ic k -w a lle d .
A r e la t iv e c o m p a r is o n o f th e d e v e lo p m e n t o f c u tic le o f the th r e e
v a r ie t ie s , M cIn tosh , Jonathan and G o ld en D e lic io u s , is illu s t r a t e d in F ig u r e 24.

F ig u r e 18. T r a n s v e r s e - s e c t io n o f the fru it of M cIntosh, th r e e w e e k s
a fte r fu ll bloom (s e c o n d c o v e r ) sh o w in g th e a r e a w h e r e a t r i ­
ch om e had slo u g h e d off, th e c o m p le te c u tic le and r e g u la r e p i­
d e r m a l la y e r (X 350).

F ig u r e 19. T r a n s v e r s e - s e c t io n of the fru it o f M cIn tosh , two m o n th s
a fte r fu ll bloom sh o w in g a v e r y r e g u la r e p id e r m a l la y e r w ith
on ly slig h t in d en ta tio n s b etw een c e l l s that have b een f i lle d - in
w ith c u tic le (X 350).

F ig u r e 20. T r a n s v e r s e - s e c t io n o f the fr u it o f M cIn to sh a t m a tu r ity
sh o w in g the v e r y r e g u la r e p id e r m a l la y e r w ith on ly s lig h t in ­
d en ta tio n s b e tw e en c e l l s that h ave b een f il l e d - in w ith c u tic le
(X 350).

F ig u r e 21. T r a n s v e r s e - s e c t io n o f the fr u it o f Jonathan, th r e e w e e k s
a fte r fu ll bloom (s e c o n d c o v e r ) sh o w in g tr ic h o m e b e in g slo u g h e d
off, c o m p le te c u tic le and r e g u la r e p id e r m a l la y e r (X 350).

F ig u r e 22. T r a n s v e r s e - s e c t io n of the fr u it o f Jonathan, tw o m o n th s
a fte r fu ll bloom sh o w in g s o m e e v id e n c e o f c e l l s e p a r a tio n of
the e p id e r m a l la y e r and the fo r m a tio n o f c u tic u la r p e g s in
th e s e b r e a k s (X 350).

F ig u r e 23. T r a n s v e r s e - s e c t io n o f the fr u it o f Jonathan at m a tu r ity sh o w ­
in g s lig h t se p a r a tio n o f c e l l s o f the e p id e r m a l la y e r w ith c u tic le
fillin g in t h e s e a r e a s (X 350).

81.

T h e th ic k n e s s o f th e c u t ic le fo r e a c h tim e o f o b s e r v a tio n fo r e a c h v a r ie t y
i s th e a v e r a g e o f te n m e a s u r e m e n t s .

T h e m e a s u r e m e n t s w e r e ta k en fr o m

th e e x t r e m it y o f th e o u te r e p id e r m a l c e l l w a ll to th e o u te r p o r tio n o f th e
c u t ic le and did n ot in c lu d e th e c u tic u la r p e n e tr a tio n o f th e e p id e r m a l o r
o u te r c o r t ic a l l a y e r s .

M e a s u r e m e n ts e a r l i e r than tw o w e e k s a fte r fu ll

b lo o m ( s e c o n d c o v e r ) w e r e c o n s id e r e d u n d e s ir a b le a s th e c u tic le w a s in ­
c o m p le te u n til t h is tim e , and th e r e la t iv e l y th in a r e a s th at c o u ld b e o b s e r v e d
and m e a s u r e d w e r e o n ly in is o la t e d p a t c h e s .
H is t o lo g ic a l s tu d ie s o f G o ld en D e lic io u s a p p le s fr o m th e H o r ti­
c u ltu r a l fa r m , E a s t L a n sin g , in 1956 s p r a y e d w ith g ly o d in h a v e r e v e a le d
w hy r u s s e t in g in th is v a r ie t y m a y r e s u lt fr o m a g ly o d in - f r e e z in g te m p e r a ­
tu r e in t e r r e la t io n s h ip .

F ig u r e s 25 th ro u g h 28 a r e p h o to m ic r o g r a p h s i l l u s ­

tr a tin g t h is r u s s e t fo r m a tio n .
T h e f i r s t e v id e n c e o f r u s s e t on G o ld en D e lic io u s a p p le s c o u ld be
o b s e r v e d w ith th e a id o f a hand le n s e a p p r o x im a te ly s i x w e e k s a ft e r fu ll
b lo o m .

S h o r tly t h e r e a f t e r it c o u ld b e s e e n w ith th e u n a id ed e y e and a p p e a r e d

a s s m a ll, ir r e g u la r , b row n , s c a ly s p o ts , s c a t t e r e d on th e fr u it s u r fa c e .
A s th e fr u it m a tu r e d , t h e s e s p o ts in c r e a s e d in both s i z e and ir r e g u la r it y .
A t th e tim e o f h a r v e s t , s c a l e s w e r e e a s i l y d is lo d g e d fr o m th e r u s s e t e d
areas.
In s tu d ie s o f th e p r e p a r e d h is t o lo g ic a l s e c t io n s o f r u s s e t e d t i s s u e s ,

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Figure 24. Increase in cuticle th ick n ess during growth and maturity of Golden
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83.

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F ig u r e 2 5. T r a n s v e r s e - s e c t io n o f the fr u it o f G o ld en D e lic io u s th r e e
w e e k s a fte r fu ll bloom (s e c o n d c o v e r ) sh o w in g f i r s t s ig n s o f
p r o life r a tio n of s u b -e p id e r m a l c e l l s (X 350).

F ig u r e 26. T r a n s v e r s e - s e c t io n o f the fr u it o f G old en D e lic io u s fou r
w e e k s a fte r fu ll bloom sh o w in g ru p tu re o f the c u tic le and
e p id e r m a l la y e r due to p r o life r a tio n o f the s u b -e p id e r m a l
c e l l s (X 350).

84.

th e f i r s t a b n o r m a lity o f th e e p id e r m a l la y e r o f th e G o ld en D e lic io u s w a s
o b s e r v e d m ic r o s c o p ic a lly a p p r o x im a te ly fo u r w e e k s a ft e r fu ll b lo o m .

It

a p p e a r e d a s a ru p tu r e o f tw o e p id e r m a l c e l l s and c u t ic le a p p a r e n tly c a u s e d
b y p r o lif e r a t io n o f o u te r c o r t ic a l c e l l s d ir e c t ly b en ea th th e ru p tu red c e l l s
(F ig u r e 2 6 ).

N o c u t ic le c o u ld b e o b s e r v e d on th e n e w ly e x p o s e d s u r f a c e s

o f th e r u p tu r e d c e l l s .

In m a n y a r e a s th e r e w e r e n u m e r o u s b r e a k s in the

e p id e r m a l la y e r , w ith r u p tu r e s o c c u r r in g a t in t e r v a ls o f fiv e o r s ix c e l l s .
In e v e r y in s ta n c e th e b r e a k s a p p e a r e d a s a f is s u r e o f tw o e p id e r m a l c e l l s
c a u s e d by p r o lif e r a t io n o f th e o u te r c o r t ic a l c e l l s d ir e c t ly u n d er the e p i­
d e r m a l la y e r .
E x a m in a tio n o f s a m p le s c o lle c t e d th r e e w e e k s a ft e r fu ll b lo o m
( s e c o n d c o v e r ) r e v e a le d s o m e s m a ll a r e a s o f s u b - e p id e r m a l c e l l p r o l i f e r ­
a tio n (F ig u r e 25) but no b r e a k in the e p id e r m is and c u tic le w a s found.
T h e p r o lif e r a t io n o f c e l l s h ad c a u s e d o n ly a s lig h t r i s e o f th e e p id e r m a l
la y e r and c u t ic le o f th e fr u it.
A t s ix w e e k s a ft e r fu ll b lo o m m o r e p r o lif e r a t io n o f s u b - e p id e r m a l
c e l l s w a s o b s e r v e d and q u ite s ig n ific a n t r u p tu r ed a r e a s o f th e fr u it s u r fa c e
w e r e n o tic e a b le in c r o s s - s e c t i o n (F ig u r e 2 7 ).

T h e c e l l s n e a r the o u te r

p o r tio n s o f th e f i s s u r e h ad b e c o m e so m e w h a t c r u sh e d , and c o lla p s e o f
t h e s e c e l l s w a s e v id e n t.

F ig u r e 27. T r a n s v e r s e - s e c t io n o f the fr u it o f G old en D e lic io u s s ix w e e k s
a fte r fu ll b lo o m , sh o w in g s u b -e p id e r m a l c e ll p r o lif e r a tio n and
fu rth e r e n la r g e m e n t o f the r u s s e t le s io n (X 350).

F ig u r e 28. T r a n s v e r s e - s e c t io n o f the fr u it o f G old en D e lic io u s at
m a tu r ity sh o w in g the la r g e m a s s of r u s s e t t is s u e fo r m e d from
a m e r is t e m a t ic la y e r o f c e l l s (p h ello g en ) b elow the r u s s e t e d
a r e a (X 350).

87.

A s th e fr u it c o n tin u e d to e n la r g e , th e ru p tu red a r e a s e n la r g e d
a ls o , and th e c e l l s f il lin g th e r u p tu red a r e a s w e r e s m a ll and b r ic k -s h a p e d
w h ic h a r e c h a r a c t e r is t ic o f m e r is t e m a t ic c e l l s .

T he c o v e r in g o f the

r u s s e t e d a r e a s c o n s is t e d o f la r g e m a s s e s o f h e a v ily sta in e d , c r u sh e d
c e l l s w h ic h had b e e n r u p tu r e d and c r u s h e d by th e d iv id in g c e l l s b en ea th
th em .
At m a tu r ity , a w e ll d e fin e d m e r is t e m a t ic la y e r o f c e l l s w a s o b ­
s e r v e d b elow th e r u s s e t e d a r e a s (F ig u r e 2 8 ).

T h is m e r is t e m a t ic la y e r

a p p e a r e d to h a v e d e v e lo p e d new c e l l s c e n tr ifu g a lly in a m a n n e r s im ila r
to p h e lle m fo r m a tio n o f w ood y s t e m s .

G reat m a s s e s of cru sh ed c e lls w ere

p r e s e n t in t r a n s v e r s e - s e c t i o n a b o v e th e r u s s e t e d a r e a s , w h ic h p r o b a b ly
w e r e th e s c a l e s o b s e r v e d m a c r o s c o p ic a lly on th e fr u it s u r fa c e in th e s e
r u sse te d a r e a s.
T h e r e s u l t s o f th e f ie ld s tu d ie s to e v a lu a te th e r o le o f th e t r ic h o m e s in fr u it r u s s e t in g in d ic a te d th at in ju r y to th e t r ic h o m e s , e v e n to
th e ir r e m o v a l, did not p r o m o te r u s s e t in g , b e c a u s e no r u s s e t in g w a s o b ­
s e r v e d at m a tu r ity on th e fr u it o f an y tr e a tm e n t of e it h e r v a r ie t y .

88.

DISCUSSION

E a r lie r in v e s t ig a t io n s o f a p p le fr u it r u s s e t in g h a v e in d ic a te d that
e it h e r s p r a y c h e m ic a ls (1, 11, 15, 18, 24, 43, 47, 52, 63) o r f r e e z in g t e m p e r a ­
tu r e s (1, 9, 11, 14, 15, 16, 20, 26, 29, 53, 55) had c a u s e d th is in ju ry .

R e ce n t

r e p o r t s (36, 37, 38, 39, 48) h a v e s u g g e s te d th e p o s s ib ilit y o f s lig h t c o ld in ­
ju ry to th e e p id e r m a l c e l l s o f th e fr u it w hen the a ir te m p e r a tu r e d ropp ed
to 32*>,F o r lo w e r n e a r o r d u rin g th e p e r io d o f fu ll b lo o m .

T h is s lig h t

c o ld in ju ry , in tu rn , w a s in c r e a s e d to s e v e r e in ju r y in the fo rm o f r u s s e t ­
in g by th e u s e o f c e r ta in p e s t ic id e s a fte r th e o c c u r r e n c e o f th e f r e e z in g
te m p e r a tu r e .

T h e r e w a s a ls o an in d ic a tio n that no r u s s e t in g o f th e fr u it

o c c u r r e d fr o m th e u s e o f th e s a m e p e s t ic id e c h e m ic a ls in s e a s o n s w hen
the a ir te m p e r a tu r e r e m a in e d a b o v e 32® F (3 6 ).
S in c e the fr u it o f the G o ld en D e lic io u s and Jonathan v a r i e t i e s h a v e
b e e n r e p o r te d v e r y s e n s it iv e to both p e s t ic id e c h e m ic a l and f r e e z in g t e m ­
p e r a tu r e s (21, 24, 34, 38, 40, 46, 54, 55), th is in v e s tig a tio n w a s in itia te d to
d e te r m in e th e r e la tio n s h ip b e tw e e n th e in ju r y fro m f r e e z in g te m p e r a tu r e s
and the u s e of c e r t a in p e s t ic id e c h e m ic a ls on fr u it r u s s e tin g .

T h e fr u it

o f th e M cIn to sh h a s b e e n r e p o r te d (24, 29, 35, 38) to be l e s s s e n s it iv e to
in ju r y fr o m t h e s e tw o f a c t o r s and th u s, w a s in c lu d e d in th is stu d y in th e
hop e o f e s t a b lis h in g a p o s s ib le r e a s o n fo r th e s e r e p o r te d d if fe r e n c e s of

r u s s e t in g b e tw e e n v a r i e t i e s a s a ffe c te d by c h e m ic a ls o r f r e e z in g te m p e r a ­
tu r e s .
It h a s b e e n p r e v io u s ly r e p o r te d (38) th at the u s e o f g ly o d in on
G o ld e n D e lic io u s d u r in g th e p e r io d " p re-p in k " th ro u g h " se c o n d c o v er "
r e s u lt e d in an e x c e s s i v e n u m b e r o f r u s s e t e d fr u it s e v e n in s e a s o n s w hen
th e a ir te m p e r a tu r e r e m a in e d a b o v e 32® F .

It w a s a ls o r e p o r te d (37)

th at in s o m e y e a r s e v e n th ough ca p ta n w a s the o n ly fu n g ic id e u s e d th ro u g h ­
out th e s e a s o n , r u s s e t in g o c c u r r e d on G o ld en D e lic io u s .

T h is hap p en ed in

th o s e s e a s o n s th at had a ir te m p e r a tu r e s b elow 32® F e ith e r ju st b e fo r e o r
ju s t a ft e r fu ll b lo o m .

T h e r u s s e t in g w a s th ought to be th e r e s u lt o f c o ld

in ju r y to th e fr u it and not to the u s e o f ca p ta n .

U nd er the c o n tr o lle d t e m ­

p e r a tu r e c o n d itio n s o f E x p e r im e n t 1, it w a s found th at th e u s e o f cap tan
on th e t r e e p r o te c te d fr o m f r e e z in g te m p e r a tu r e s , r e s u lt e d in no h e a v ily
r u s s e t e d fr u it.

H o w e v er , on th e t r e e e x p o s e d to te m p e r a tu r e s o f 3 1 . 7®,

3 1 . 5° and 2 8 . 0 ° F , 2 3 . 7 p e r c e n t o f th e fr u it w e r e h e a v ily r u s s e t e d (T a b le s
1 and II).

T h e s e fin d in g s w ou ld a p p e a r to s u b s ta n tia te th e p r e m is e that

f r e e z in g t e m p e r a tu r e s n e a r b lo o m c o u ld c a u s e r u s s e t in g on G o ld en D e li­
c io u s .
T h e r e s u lt s o f E x p e r im e n t 1 ten d to r e v e a l s o m e o f the fa c to r s
r e s p o n s ib le fo r fr u it r u s s e t in g o f G o ld en D e lic io u s .

A s a ll tr e a tm e n ts

w e r e m a d e on h a lf - t r e e s , th e e n v ir o n m e n ta l c o n d itio n s w e r e a s s im ila r

a s p o s s ib le b e tw e e n tr e a t m e n t s .

T h e h a lf - t r e e tr e a tm e n ts w o u ld a ls o ten d

to e lim in a t e a n y in h e r e n t v a r ia tio n s th at m ig h t e x is t b e tw e e n t r e e s .

The

p o r tio n s o f th e t r e e s s p r a y e d w ith th e g ly o d in tr e a tm e n t and p r o te c te d fro m
p o s s ib le c o ld in ju r y s t i l l p r o d u c e d fr u it w ith s o m e d e g r e e o f r u s s e t in g
(T a b le II).

M o r e o v e r , th e u s e o f g ly o d in on th e fr u it e x p o s e d to a ir t e m ­

p e r a t u r e s lo w e r th an 32®F fo r th r e e n ig h ts d u rin g th e b lo s s o m in g p e r io d
r e s u lt e d in an e v e n la r g e r n u m b er o f fr u it s e x h ib itin g both lig h t and
h e a v y r u s s e t in g (T a b le II).
C o m p a r in g fr u it s fr o m th e s a m e G o ld en D e lic io u s t r e e s s p r a y e d
w ith d iffe r e n t fu n g ic id e s o f E x p e r im e n t 1, c a r r ie d on in 1956, th e u s e o f
c a p ta n r e s u lt e d in a m u ch s m a lle r p e r c e n t a g e o f fr u it s e ith e r lig h tly o r
h e a v ily r u s s e t e d and a la r g e r p e r c e n ta g e c o m p le te ly f r e e o f r u s s e t in g th an
w a s fou nd fr o m th e u s e o f g ly o d in (T a b le II).

In fa c t th e p e r c e n ta g e of

h e a v ily and lig h tly r u s s e t e d f r u it s o f th e c a p ta n tr e a tm e n t and e x p o s e d to
th e f r e e z in g t e m p e r a t u r e s g iv e n in T a b le II i s v e r y s im ila r to th o s e o f
th e g ly o d in tr e a tm e n t o f th e t r e e p r o t e c t e d a g a in s t e x p o s u r e to f r e e z in g
te m p e r a tu r e s (T a b le II).
In 1957, w h en g ly o d in , u s e d a t fu ll s tr e n g th (o n e qu art p e r 100
g a llo n s ), w a s c o m p a r e d to g ly o d in a t o n e p in t p lu s fo u r o u n c e s o f P h ygon
p e r 100 g a llo n s , th e p e r c e n ta g e o f h e a v ily r u s s e t e d fr u it w a s a p p r e c ia b ly
lo w e r fo r th e g ly o d in -P h y g o n tr e a tm e n t, T a b le V .

Phygon h a s b een

91 .

r e p o r t e d fa v o r a b le fo r p r o d u c in g u n b le m is h e d fr u it on G o ld en D e lic io u s
(3 5 ).
T h e te m p e r a tu r e c o n d itio n s in 1957 w e r e d iffe r e n t than in 1956
(T a b le s I an d V I).
tu r e o f 3 1 . 0 ° F .
2 7 . 5° F .

In 1957 o n e t r e e w a s e x p o s e d to a s in g le low t e m p e r a ­

T r e e n u m b e r 2 e x p e r ie n c e d a m in im u m te m p e r a tu r e o f

T r e e n u m b e r 3 and th e c o n tr o l t r e e tr e a te d w ith ca p ta n w e r e

e x p o s e d to m in im u m te m p e r a tu r e s o f 2 7 . 5 ° , 30. 5*, 31. 5° and 30. S^F.
T h e s e r e c o r d e d te m p e r a tu r e s o c c u r r e d d u rin g th e e a r ly p in k and pin k
s t a g e s o f d e v e lo p m e n t.
T h e r e s u l t s (T a b le V) in d ic a te th at a lth o u g h a la r g e p e r c e n ta g e
o f fr u it s w e r e h e a v ily r u s s e te d , a r e d u c tio n in s e v e r it y o f h e a v y r u s s e t ­
in g w a s o b s e r v e d w h e r e g ly o d in w a s u s e d at r e d u c e d s tr e n g th .

H o w ev er,

a s th e e x p o s u r e to f r e e z in g te m p e r a tu r e s in c r e a s e d , th e m a g n itu d e o f
th e d iffe r e n c e in h e a v y and lig h t r u s s e t in g w a s l e s s .

T h e fa c t th at 96. 0

p e r c e n t o f th e f r u it s fr o m th e ca p ta n tr e a tm e n t w e r e h e a v ily r u s s e t e d
in d ic a te d th at f r e e z in g te m p e r a tu r e s w e r e a m a jo r c a u s e o f r u s s e t in g
on th e t r e e s e x p o s e d to th e fo u r p e r io d s o f te m p e r a tu r e s b elo w 32° F .
T h e u s e o f c a p ta n r e s u lt e d in m u ch l e s s r u s s e t in g on th is v a r ie t y
in 1956 th an g ly o d in fo llo w in g f r e e z in g te m p e r a tu r e s (T a b le II); but, w hen
n u m e r o u s f r e e z in g p e r io d s o c c u r r e d n e a r b lo o m in 1957, e v e n th e fr u it s
o f th e ca p ta n tr e a tm e n t w e r e s e v e r e l y r u s s e t e d (T a b le V ).
w ith p r e v io u s o b s e r v a t io n s (3 8 ).

T h is a g r e e s

92.

T h e fin d in g s o f s tu d ie s c o n d u cted at th e G raham E x p e r im e n t
S ta tio n in 1956, E x p e r im e n t 2, c o m p a r in g g ly o d in and cap tan on G old en
D e lic io u s , in d ic a te d th at th e u s e o f g ly o d in did not c a u s e a s ig n ific a n tly
g r e a t e r a m ou n t o f e it h e r h e a v y o r lig h t r u s s e t in g than th e u s e o f cap tan .
T h e n e a r a b s e n c e o f r u s s e t in g o f G o ld en D e lic io u s in th is stu d y (T a b le
III) e v e n w hen g ly o d in w a s u se d , a lth o u g h a te m p e r a tu r e o f 30. 5®F w a s
r e c o r d e d at e a r ly pink, h a s a p o s s ib le e x p la n a tio n .

T he s ta g e of flo r a l

d e v e lo p m e n t w a s su c h th at the r e c e p t a c le w a s p a r tia lly p r o te c te d fro m
f r e e z in g in ju ry by th e flo r a l b r a c ts and th e y o u n g le a v e s su r ro u n d in g
th e flo w e r c lu s t e r .

A ls o , the 3 0 . 5* F te m p e r a tu r e w a s r e c o r d e d fo r

s lig h tly l e s s than th ir ty m in u te s ju s t b e fo r e s u n r is e , w h ich c o u ld h a v e
b een too sh o r t a p e r io d of tim e to c a u s e f r e e z in g in ju ry .
T h e m e th o d o f a p p lic a tio n m a y h a v e b e e n a n o th e r fa c to r .

In

E x p e r im e n t 1, an a d ju s ta b le n o z z le gun w a s u s e d to m a k e th e a p p lic a tio n s .
E v en though th e o p e r a tin g p r e s s u r e w a s o n ly 150 p ou n d s p e r sq u a r e inch,
th e gun w a s o p e r a te d w ith in tw o fe e t o f th e le a v e s and fr u it.

T h u s, the

d r o p le ts c o u ld h ave h it th e f lo w e r s and fr u it at a g r e a t e r fo r c e than w hen
th e a i r - b l a s t a tta c h m e n t w a s u s e d to m a k e th e a p p lic a tio n s in E x p e r im e n t 2.
T h is p o s s ib le m e c h a n ic a l in ju ry h a s b e e n su p p o rted by o b s e r v a t io n s by
M itc h e ll and K r e tc h m a n (41).
In 1957, the s a m e p e s t ic id e c h e m ic a ls u s e d on G o ld en D e lic io u s
in 1956, w e r e a p p lie d a s h a lf - t r e e tr e a tm e n ts on Jonathan u n d er c o n tr o lle d

93.

t e m p e r a tu r e c o n d itio n s (E x p e r im e n t 4 ).

T h r e e t r e e s w e r e e x p o s e d to

v a r io u s f r e e z in g te m p e r a tu r e s : (1) 32. O^F m in im u m ; (2) 2 7 . 5 ° F m in im u m ;
and (3) 2 7 . 5*", 30. 5 ° , 31. 5** and 30. 5 ° F m in im u m te m p e r a tu r e s (T a b le VI).
T h e m a g n itu d e o f d if fe r e n c e o f r u s s e t in g o f th is v a r ie t y w a s not a s g r e a t
a s w ith th e s a m e m a t e r ia ls on th e G o ld en D e lic io u s v a r ie t y .

N e v e r t h e le s s ,

th e g e n e r a l p a tte r n w a s s o m e w h a t s im ila r .
T h e am ou n t of h e a v y fr u it r u s s e t in g on Jonathan w a s n e a r ly eq u a l
fo r both g ly o d in and ca p ta n on th e t r e e e x p o s e d to a 32. 0 ° F m in im u m t e m ­
p e r a tu r e .

H o w e v e r , th e am ou n t o f lig h t r u s s e t in g fro m th e g ly o d in t r e a t ­

m e n t w a s g r e a t e r , 4 8 . 53 p e r c e n t, a s c o m p a r e d to 19. 51 p e r c e n t fr o m th e
ca p ta n tr e a tm e n t (T a b le V ).

A t a lo w e r m in im u m te m p e r a tu r e (2 7 . 5®F)

th e am ou n t o f h e a v y r u s s e t in g fro m th e c a p ta n tr e a tm e n t w a s o n ly o n e -h a lf
the a m ou n t r e s u lt in g fr o m the g ly o d in tr e a tm e n t, 3. 29 p e r c e n t and 7. 55
p e r c e n t, r e s p e c t iv e ly .

T h e lig h t r u s s e t in g fr o m both th e g ly o d in and c a p ­

ta n tr e a tm e n ts did not v a r y g r e a t ly fr o m th at o f th e fr u it e x p o s e d to 3 2 . 0 * F .
T h e g r e a t e s t d if fe r e n c e b e tw e e n s p r a y tr e a tm e n ts o c c u r r e d on th e t r e e
e x p o s e d to the fo u r p e r io d s o f f r e e z in g te m p e r a tu r e s , 2 7 . 5*, 30. 5**, 31. 5°
a n d 30. 5*F (T a b le V ).

T h e p o r tio n r e c e iv in g th e ca p ta n tr e a tm e n t had

15. 52 p e r c e n t o f th e fr u it h e a v ily r u s s e t e d c o m p a r e d to 6 7 . 07 p e r c e n t
h e a v ily r u s s e t e d fr u it fr o m th e g ly o d in tr e a tm e n t.

T h e p o r tio n o f th e

h a r v e s t e d f r u it s f r e e o f r u s s e t in g w a s 37. 93 p e r c e n t fo r the ca p ta n t r e a t -

94.

m e n t and o n ly 4. 88 p e r c e n t fo r th e g ly o d in tr e a tm e n t.

F ie ld s tu d ie s

(T a b le s IV and VII) u s in g th e s a m e m a t e r ia ls , su p p o rted th e s e fin d in g s
o f th e c o n tr o lle d te m p e r a tu r e s tu d ie s (T a b le V ).

T h is a p p e a r e d to s u b ­

s ta n tia te p r e v io u s o b s e r v a t io n s (35) th at c e r ta in c h e m ic a ls m a y c a u s e
s o m e d e g r e e o f r u s s e t in g on Jonathan, but th e s e s a m e m a t e r ia ls m a y
a c c e n tu a te th e am ou n t o f r u s s e t in g if a p p lie d a fte r a c o ld p e r io d n e a r
b lo o m .
T h e a m ou n t o f r u s s e t in g fr o m th e g ly o d in tr e a tm e n t in fie ld
s tu d ie s on Jonathan w a s l e s s than found in th e c o n tr o lle d te m p e r a tu r e
s tu d ie s .

H e r e a g a in , th e p e r io d o f e x p o s u r e to f r e e z in g te m p e r a tu r e s

w a s l e s s in the f ie ld in v e s t ig a t io n s .

A ls o , the a p p lic a tio n in th e f ie ld

b e in g m a d e w ith an a i r - b l a s t s p r a y e r , c o u ld h a v e c a u s e d l e s s m e c h a n ic a l
in ju r y th an r e s u lt e d fr o m th e u s e o f an a d ju s ta b le n o z z le gun in th e c o n ­
tr o lle d te m p e r a tu r e e x p e r im e n ts (41).
It w a s s ig n ific a n t to n ote th at in th e p lo t r e c e iv in g th e ca p ta n
tr e a tm e n t u n d er f ie ld c o n d itio n s , r e s u lt e d in h e a v y r u s s e t in g th at w a s
s ig n ific a n tly h ig h e r th an th at fr o m the u s e o f s u lfu r in th e a d ja c e n t p lo t
(T a b le V II).

A lth o u g h th e ca p ta n p lo t w a s s lig h tly lo w e r in e le v a tio n ,

th is w o u ld a p p e a r to su b s ta n tia te p r e v io u s fin d in g s (35, 38) to th e e f f e c t
th at th e u s e o f w e tta b le s u lfu r on Jonathan m a y r e s u lt in a m o r e f a v o r ­
a b le f in is h w hen f r e e z in g te m p e r a tu r e s o c c u r n e a r b lo o m .

95.

It sh o u ld be m e n tio n e d th a t Phygon w a s u s e d in a ll tr e a tm e n ts at
th e G ra h a m E x p e r im e n t S ta tio n in 1 957.

In fie ld s tu d ie s not a p a r t o f th is

in v e s tig a tio n , m a d e on Jonathan in g r o w e r 's o r c h a r d s in 1957, it w a s
found th at fr u it fr o m th e u s e o f P hygon p lu s ca p ta n fo llo w in g th e o c c u r r e n c e
o f an a ir te m p e r a tu r e b elo w 32° F , had a g r e a t e r am ou nt o f r u s s e t in g than
that r e s u lt in g fr o m th e u s e o f w e tta b le su lfu r p lu s a m e r c u r ia l com pou nd.
A s th e u s e o f w e tta b le s u lfu r on Jonathan at the G raham E x p e r im e n t S ta tio n
g a v e l e s s r u s s e t in g than cap tan , it m a y be d ed u cted th at Phygon c o u ld be
u n fa v o r a b le to u s e on Jonathan fo llo w in g th e o c c u r r e n c e o f f r e e z in g t e m ­
p e r a t u r e s c l o s e to b lo o m .

A se c o n d fie ld stu d y in a g r o w e r ’s o r c h a r d

c a r r ie d on in th e y e a r s 1955, 1956 and 1957 h a s show n th at th e u s e o f
g ly o d in on Jonathan r e s u lt e d in no m o r e h e a v ily r u s s e t e d fr u it than th e u s e
o f ca p ta n .

B a sed on th e s e o b s e r v a t io n s , th e r e is a p o s s i b ilit y that th e

h ig h w e ttin g p r o p e r t ie s o f g ly o d in (27) e n h a n ce d th e c a p a c ity o f P h ygon to
in c r e a s e th e am ou n t o f h e a v ily r u s s e t e d fr u it a t th e G rah am E x p e r im e n t
S tation in 1957.
No s m a ll t r e e s o f M cIn to sh w e r e a v a ila b le fo r c o n tr o lle d t e m p e r ­
a tu r e s tu d ie s .

N e v e r t h e le s s , th e fie ld s tu d ie s su p p o rt p r e v io u s o b s e r v a ­

tio n s (24, 29, 35, 38) th at M cIn to sh fr u it s a r e m u ch l e s s s e n s it iv e to the
e f f e c t s o f f r e e z in g te m p e r a tu r e s and p e s t ic id e c h e m ic a ls on fr u it r u s s e t in g
(T a b le s III, IV, V II).

N o s ig n ific a n t d if fe r e n c e s w e r e n o ted fo r th e fu n g ic id e s

96.

u s e d on th is v a r ie t y r e g a r d le s s o f the e x p o s u r e to v a r y in g a m o u n ts of
f r e e z in g te m p e r a tu r e s a s e x p e r ie n c e d at the G raham E x p e r im e n t S ta tio n
in 1956 and 1 9 5 7 .
T h e c o m p a r is o n o f th e fin d in g s o f 1956 w ith th o s e o f 1957, E x p e r i­
m e n ts 2 and 4 at the G raham E x p e r im e n t S tation , u s in g th e s a m e p e s t ic id e
c h e m ic a ls fo r th e tw o y e a r s on th e s a m e t r e e s and a p p lie d w ith the sa m e
e q u ip m e n t, in d ic a te d that s ig n ific a n tly m o r e r u s s e t in g o c c u r r e d on the
Jonathan and M cIn to sh v a r ie t ie s in 1957 than in 1956.

T h e o n ly a p p a ren t

d if fe r e n c e b e tw e e n th e tw o s e a s o n s w a s d u ra tio n o f th e te m p e r a tu r e s b e ­
low 32® F .

A s in g le low o f 30. 5 ° F o c c u r r e d in 1956 ju st b e fo r e b lo o m ,

w h e r e a s in 1957, p e r io d s o f 31. 5®, 3 1 .0 ° and 31. 5®F w e r e r e c o r d e d d u r ­
in g th e b lo s s o m in g p e r io d .
To s u m m a r iz e , th e k n ow led g e o f in t e r r e la t io n s h ip s b e tw e e n f r e e z ­
in g te m p e r a tu r e and u s e o f c e r t a in fu n g ic id e s ten d to r e v e a l s o m e o f the
fa c to r s r e s p o n s ib le fo r r u s s e t in g .

F r o m th e fin d in g s w h e r e th e a ir t e m ­

p e r a tu r e w a s c o n tr o lle d , T a b le s II and V, and fro m s tu d ie s m a d e u n d er
c o m m e r c ia l o r c h a r d c o n d itio n s ,

T a b le s III, IV, VII and VIII, it m a y be

sta te d that a ir t e m p e r a tu r e s o f 32® F o r b elo w m a y c a u s e s o m e fr u it r u s s e t ­
in g on th e v a r i e t i e s Jonathan, G o ld en D e lic io u s and to a l e s s e r e x te n t on
M c In to sh .
c id e s .

T h is r u s s e t in g m a y be in c r e a s e d by th e u s e o f c e r ta in fu n g i­

T h u s, it is e v id e n t th at n e w ly in tro d u c ed p e s t i c id e s d e s ig n e d fo r

u s e n e a r and d u rin g b lo o m sh o u ld be stu d ied on the s o - c a ll e d s e n s it iv e a p p le
v a r i e t i e s to d e te r m in e th e ir e ffe c t on fr u it r u s s e tin g .

97.

H is t o lo g ic a l S tu d ie s

T h e m e th o d o f in itia tio n and th e d e v e lo p m e n t o f r u s s e t e d t i s s u e s
o f th e a p p le h a v e b e e n d is c u s s e d b y v a r io u s w o r k e r s (1, 3, 4, 24, 55, 57, 58, 60,
6 4 ).

T h e g e n e r a l c o n s e n s u s o f o p in io n w a s th at th e b a s e s o f th e tr ic h o m e s

and th e s to m a ta r e p r e s e n t w e a k s p o ts in the e p id e r m a l la y e r .

T h ey s u g ­

g e s t e d th at in ju r y to the t r ic h o m e s by f r e e z in g te m p e r a tu r e s , o r e n tr y of
a p e s t ic id e c h e m ic a l th rou gh th e gap le ft a fte r the tr ic h o m e s slo u g h e d off,
o r th rou gh s to m a ta l o p e n in g s r e s u lt s in k illin g o f e p id e r m a l c e l l s a d ja ce n t
to t h e s e o p e n in g s .

A s th e fr u it d e v e lo p e d , t h e s e a r e a s o f dead e p id e r m a l

c e l l s w e r e u n a b le to co n tin u e m e r is t e m a t ic a c tiv ity and th u s the e p id e r m a l
s u r fa c e s p lit and e x p o s e d s u b -e p id e r m a l c e l l s .

T h e r u s s e t w a s thought to

d e v e lo p fr o m m e r is t e m a t ic a c t iv it y o f th e u n d e r ly in g c e l l s a s a n o r m a l
h e a lin g p r o c e s s o f th is c r a c k o r b r e a k in th e e p id e r m a l s u r fa c e .
T h e r e s u lt s o f the h is t o lo g ic a l in v e s tig a tio n s o f th e d e v e lo p m e n t
o f r u s s e t in g on G o ld en D e lic io u s m a d e in th is stu d y w e r e not in a c c o r d
w ith t h e s e p r e v io u s ly r e p o r te d o b s e r v a t io n s .

M ic r o s c o p ic s tu d ie s o f the

fr u it o f th e G o ld en D e lic io u s tr e a te d w ith g ly o d in and e x p o s e d to f r e e z in g
te m p e r a tu r e s (E x p e r im e n t 5) r e v e a le d th at th e n u m b e r s o f b r e a k s in th e
c u t ic le and e p id e r m a l la y e r o f fr u it w e r e e v id e n t a t fo u r w e e k s a fte r fu ll
b loom (F ig u r e 2 6 ).

T h is w a s not found on th e d e v e lo p in g fr u it p r o te c te d

fr o m f r e e z in g te m p e r a tu r e s and s p r a y e d w ith captan (F ig u r e 15).

F u r th e r -

98.

m o r e , t h e s e b r e a k s w e r e not a s s o c ia t e d w ith th e p r e s e n c e o f tr ic h o m e s
o r s to m a ta , F ig u r e 26.
S e c o n d ly ,

n e w ly e x p o s e d s u r fa c e o f the le s i o n s o r c r e v i c e s w e r e

not c o v e r e d w ith a c u t ic le (F ig u r e 26) a s w a s found w hen th e tr ic h o m e s
slo u g h e d o ff (F ig u r e 15).

In th is stud y, th e f i r s t e v id e n c e o f c u tic u la r i-

z a tio n w a s a t th e b a s e o f th e tr ic h o m e s (F ig u r e 13) and a s fu r th e r c u tic le
d e p o s itio n o c c u r r e d , th e tr ic h o m e a p p e a r e d to be a c tu a lly fo r c e d out o f
th e e p id e r m a l la y e r by th e d e v e lo p in g c u tic le ( F ig u r e s 14 and 15).

T h is

s u g g e s t s th at if the o b s e r v e d r u p tu r in g o f th e e p id e r m a l s u r fa c e found
fo u r w e e k s a fte r fu ll b lo o m , F ig u r e 26, w a s r e la t e d to lo c a tio n o f tr ic h o m e s ,
th e n e w ly e x p o s e d in te r n a l s u r fa c e o f the l e s i o n s o r c r e v i c e s w o u ld be
c o v e r e d w ith a c u t ic le (F ig u r e 15).

T h is w a s not o b s e r v e d , F ig u r e 26.

T o fu r th e r c o n fir m th e fa c t th at r u s s e t in g m a y n ot be a s s o c ia t e d
w ith r e m o v a l o r in ju r y to t r ic h o m e s , t r ic h o m e s w e r e r e m o v e d m e c h a n i­
c a lly fr o m th e flo r a l r e c e p t a c le s and y o u n g fr u it s in d is tin c t s t r ip s at
v a r io u s s t a g e s o f d e v e lo p m e n t.

At th e s a m e tim e , th e tip s o f th e t r i ­

c h o m e s o f o th e r f lo w e r s and f r u it s w e r e in ju r e d w ith d ry ic e .

T h is w a s

done on G o ld en D e lic io u s and Jonathan t r e e s e x p o s e d to f r e e z in g t e m p e r a ­
t u r e s and s p r a y e d w ith cap tan (E x p e r im e n t 5).

S in ce no r u s s e t in g o c c u r r e d

on t h e s e in ju r e d fr u it s , th e fr u it r u s s e t in g r e s u lt in g fro m th e fu n g ic id e s
u s e d in th is stu d y c o u ld not be a s s o c ia t e d d ir e c tly w ith in ju r y to the tr ic h o m e s
on th e fr u it.

99.

T h e e a r l i e s t a p p a re n t d e v e lo p m e n t o f fr u it r u s s e t in g w a s show n
in F ig u r e 25.

C e r ta in s u b - e p id e r m a l c e l l s in th e o u te r c o r t ic a l la y e r

d iv id e d p e r ic l in a lly and a n t ic lin a lly r e s u lt in g in a s m a ll group o f c e l l s
w h ich , a s th is p r o lif e r a t io n con tin u ed , ru p tu red th e e p id e r m a l la y e r and
c u t ic le .

T h is w a s illu s t r a t e d in F ig u r e 26.

A s th e fr u it c o n tin u e d to e n ­

la r g e , th e le s i o n s o r c r e v i c e s b e c a m e w id e r .

P r o life r a tio n o f c e l l s c o n ­

tin u ed , and th e in te r n a l p r e s s u r e c a u s e d th e o u te r c e l l s to c o lla p s e and
b e c o m e c r u s h e d and e v e n tu a lly th e c r u s h e d

c e l l s slo u g h e d off.

A s c e ll

d e v e lo p m e n t co n tin u ed , a d is tin c t la y e r o f s m a ll, b r ic k -s h a p e d , n o n ­
v a c u o la te d c e l l s h a v in g the c h a r a c t e r is t ic s o f a ca m b iu m , w a s fo r m e d
b elow th e le s io n (F ig u r e 2 8 ).
p h e llo g e n (1, 3, 4, 29, 55, 6 0 ).

T h is c a m b ia l- lik e la y e r h a s b e e n te r m e d a
It c o n tin u e d to fo rm p h e lle m c e n tr ifu g a lly

in the s a m e m a n n e r a s a p h e llo g e n in a w o o d y d ic o ty le d o n o u s s te m (13).
T h e la t e r s t a g e s o f a c tu a l r u s s e t fo r m a tio n o b s e r v e d in th is stu d y
ten d to a g r e e w ith p r e v io u s fin d in g s (1, 3, 4, 24, 29, 55, 57, 60, 64) but the
r e a s o n s fo r fr u it r u s s e t in g a s a s s o c ia t e d w ith in ju r y to t r ic h o m e s and c e l l s
a d jo in in g s to m a ta w e r e not e v id e n t in th is in v e s tig a tio n .

Injury and r e s u l t ­

ant r u s s e t in g in t h e s e s tu d ie s a p p e a r e d a s m e r is t e m a t ic a c tiv ity o f o u te r
c o r t ic a l c e l l s w h ich , in tu rn , f o r c e f u lly ru p tu red the e p id e r m a l la y e r .
T h e r e w a s no c o lla p s e d o r dead e p id e r m a l c e l l s o r t r ic h o m e s to b r in g
abou t m e r is t e m a t ic a c t iv it y o f o u te r c o r t ic a l c e l l s .

T h is m e r is t e m a t ic

a c t iv it y a p p a r e n tly w a s in d u c ed e it h e r by th e fu n g ic id e g ly o d in o r by th e
b r ea k d o w n p r o d u c ts o f g ly o d in o r by a d ju v a n ts in c lu d e d in th e fo r m u la tio n
o f g ly o d in , w h ich p a s s e d th ro u g h th e e p id e r m a l la y e r and c a m e in c o n ta c t
w ith th e o u te r c o r t ic a l c e l l s .

W h eth er tr a n s lo c a tio n to o k p la c e b e tw e en

th e e p id e r m a l c e l l s o r th ro u g h th e e p id e r m a l c e l l s i s not known.

It d o e s

s e e m a p p a re n t, h o w e v e r , th at e x p o s u r e o f th e r e c e p t a c le o f th e flo w e r s
o r f r u it s to a f r e e z in g te m p e r a tu r e o f 32*"F o r lo w e r n e a r o r d u rin g b lo o m ,
in c r e a s e s th e e a s e by w h ich th e fu n g ic id e m a y p a s s th ro u g h th e e p id e r m a l
la y e r .

T h is p r e m is e i s b a s e d on th e fa c t th at th e p e r c e n ta g e o f G o ld en

D e lic io u s f r u it s h e a v ily and lig h tly r u s s e t e d w a s g r e a t e r fr o m th e u s e o f
g ly o d in w h en t e m p e r a tu r e s b elo w 3 2 ° F o c c u r r e d n e a r b lo o m in 1956 than
fr o m th e u s e o f g ly o d in w hen th e a ir te m p e r a tu r e w a s not a llo w e d to f a ll
b elo w 32. 5° F (T a b le II).
S tu d ie s o f th e p r o t e c t iv e l a y e r s o f th e th r e e v a r i e t i e s , M cIn to sh ,
G o ld en D e lic io u s and Jonathan, g a v e s o m e in s ig h t in to th e r e a s o n s fo r th e
d if f e r e n c e s b e tw e e n v a r i e t i e s r e la t iv e to th e ir s u s c e p t ib ilit y to r u s s e t in g .
It a ls o o ff e r e d a p o s s ib le e x p la n a tio n o f th e in t e r r e la t io n s h ip b e tw e e n
f r e e z in g te m p e r a tu r e s and c e r t a in p e s t ic id e c h e m ic a ls a s th e y a ff e c t fr u it
r u s s e t in g .
S tu d ie s by M o d lib o w sk a and R o g e r s (42) on th e f r e e z in g o f p la n t
t i s s u e s u n d er th e m ic r o s c o p e r e v e a le d that ic e u s u a lly fo r m e d in th e in t e r -

101.

c e ll u la r s p a c e s f ir s t .

H o w e v er , if no in t e r c e llu la r s p a c e s w e r e p r e s e n t,

a s in m e r is t e m a t ic t i s s u e s , th ey o b s e r v e d th at in s o m e c a s e s a c tu a l f r e e z ­
in g o f th e c e l l w a lls o c c u r r e d , w h ich in s o m e in s ta n c e s r e s u lt e d in the
lo n g itu d in a l s p litt in g o f the c e l l w a lls a lo n g the m id d le la m e lla ,
th e s e p a r a t e d c e l l s u n d am aged .

le a v in g

T h e ir s tu d ie s w e r e m a d e on T r a d e s c a n tia

s ta m in a l h a ir s , r e c e p t a c le s o f a p p le f lo w e r s , and m o s s le a v e s (P te r y g o p h y llu m lu c e n s ).
It w a s a ls o o b s e r v e d by th e s e a u th o r s (42) that the c u tic le , th e
c e l l w a ll and th e e c to p la s m to g e th e r fo r m e d an e ffe c t iv e b a r r ie r a g a in s t
ic e in o c u la tio n .

T h e y o b s e r v e d th at an u n d a m a g ed c u tic le p r o te c te d both

th e e p id e r m a l h a ir s and th e e p id e r m a l c e l l s fr o m ic e in o c u la tio n .

B e c a u se

th e e p id e r m a l c e l l s w e r e fr e q u e n tly s m a ll and th ic k -w a lle d , th e u n d e r ly in g
la y e r of th in -w a lle d c e l l s w e r e in o c u la te d w ith ic e b e fo r e th e e p id e r m a l
c e l l s and th u s th e y w e r e th e f i r s t to f r e e z e and, in tu rn , in o c u la te d th e
o v e r ly in g e p id e r m a l c e l l s w ith ic e .
S tu d ie s o f th e d e v e lo p m e n t o f th e c u tic le , E x p e r im e n t 5, r e v e a le d
th at no c u tic le w a s p r e s e n t on th e e x te r n a l s u r fa c e at th e p r e - p in k s ta g e o f
flo w e r d e v e lo p m e n t w h en th e r e c e p t a c le i s u s u a lly c o m p le te ly e x p o s e d .
H o w e v e r , s o m e c u tin iz a tio n o f the e x p o s e d w a ll o f th e e p id e r m a l c e l l s w a s
ta k in g p la c e .

A s th e flo w e r c o n tin u e d to d e v e lo p , m o r e c u tin iz a tio n o c c u r r e d

and at fu ll b lo o m a s m a ll am ou n t o f e x te r n a l c u tic le c o u ld be o b s e r v e d n e a r

th e b a s e o f th e tr ic h o m e (F ig u r e 9).

A t p e ta l fa ll, a d is tin c t e x te r n a l c u t ic le

w a s p r e s e n t an d su r r o u n d e d th e b a s e o f th e t r ic h o m e s , a s illu s t r a t e d by
F ig u r e 13, and a p p r o x im a te ly s e v e n d a y s a fte r p e ta l fa ll ( f ir s t c o v e r ), the
c u t ic le w a s c o m p le te (F ig u r e 14).
T h u s, it w a s a p p a re n t th at fo r th e th r e e v a r ie t ie s in clu d ed in th is
stu d y th a t th e r e c e p t a c le o f th e f lo w e r s and the y o u n g f r u it s w a s not c o m ­
p le t e ly p r o te c te d by c u t ic le b e tw e e n th e tim e th e r e c e p t a c le w a s f i r s t e x ­
p o s e d to e n v ir o n m e n ta l c o n d itio n s (p r e -p in k ) and u n til s h o r tly b e fo r e
fir s t c o v er .
T h is p r o v id e s a p o s s ib le e x p la n a tio n fo r th e f u n g ic id e - v a r ie t y te m p e r a tu r e in t e r r e la t io n s h ip d e v e lo p e d fr o m th is s e r i e s o f s tu d ie s .

If

f r e e z in g t e m p e r a tu r e s o c c u r d u rin g o r n e a r fu ll b lo o m w h en th e fr u it i s
not p r o t e c t e d by a c u t ic le , in ju r y fr o m ic e in o c u la tio n to s u b - e p id e r m a l
c e l l s m a y ta k e p la c e w ith ou t a p p a re n t in ju r y to the e p id e r m a l c e l l s .

The

s u b se q u e n t h e a lin g o f t h e s e in ju r e d a r e a s o f c e l l s m a y c a u s e c e l l p r o l i f e r ­
a tio n that m a y e v e n tu a lly r u p tu re th e e p id e r m is .

S u b seq u en t r u s s e t in g

m a y d e v e lo p on th e v a r i e t i e s m o r e s u s c e p t ib le to in o c u la tio n o f ic e in
s u b - e p id e r m a l a r e a s , su c h a s Jonathan and G old en D e lic io u s , and not th e
M cIn to sh .

S in c e th e f lo r a l r e c e p t a c le and v e r y you n g fr u it i s v e r y m e r i s ­

t e m a t ic d u r in g t h is e a r ly s ta g e a s w a s o b s e r v e d by v a r io u s w o r k e r s (2,
57, 58, 59), th e r e m a y be lit t le , if any, in t e r c e llu la r s p a c e s in th e c o r t ic a l

103.

t i s s u e s and the e p id e r m is , so th at f r e e z in g te m p e r a tu r e s m a y , a s w a s
fou nd by M o d lib o w sk a e t a l. (42) c a u s e a te m p o r a r y s e p a r a tio n o f th e c e l l s
o f th e e p id e r m a l la y e r .

If a c e r ta in p e s t ic id e c h e m ic a l i s a p p lie d fo llo w ­

in g th is in ju r y and p r io r to th e fo r m a tio n o f a c o m p le te c u t ic le , th e c h e m ­
ic a l m a y a c tu a lly p e n e tr a te th e e p id e r m is in to th e o u te r c o r t ic a l c e l l s
c a u s in g m e r is t e m a t ic a c tiv ity o f th e s e c e l l s a s illu s t r a t e d in F ig u r e s 25, 26
and 2 7 .

T h is , in turn, w ou ld in c r e a s e th e n u m b er o f r u p tu r ed a r e a s and

i n c r e a s e th e d e g r e e o f fr u it r u s s e t in g b eyon d that n o r m a lly o c c u r r in g fr o m
f r e e z in g te m p e r a tu r e s a lo n e (T a b le II).

H o w e v er , th is s e p a r a tio n o f the

c e l l s o f th e e p id e r m a l la y e r , d e s c r ib e d by M o d lib o w sk a (42) w a s not o b ­
s e r v e d in th e m a t e r ia l s tu d ie d in th is in v e s tig a tio n .
T h e s e v e r it y o f fr u it r u s s e t in g a p p e a r e d to be c o r r e la t e d w ith th e
r e la t iv e tim e f r e e z in g te m p e r a tu r e s o c c u r r e d and th e d e v e lo p m e n t o f c u t ic le
on th e y o u n g fr u it.

In 1957, T r e e s 1 and 2 o f G o ld en D e lic io u s tr e a te d w ith

g ly o d in (T a b le V) w e r e e x p o s e d to f r e e z in g te m p e r a tu r e s o c c u r r in g at e a r ly
p in k .

In 1956, th e e x p o s e d t r e e r e c e iv in g th e g ly o d in tr e a tm e n t w a s s u b ­

je c te d to th r e e p e r io d s o f f r e e z in g te m p e r a tu r e s a t pink, e a r ly b lo o m and
e a r ly p e ta l f a ll (T a b le I).
s im ila r (T a b le s II an d V I).

H o w e v er , th e am ou n t o f r u s s e t e d fr u it s w a s v e r y
T h e la c k o f c u tic u la r iz a tio n o f th e flo w e r r e c e p ­

ta c le at th e e a r l i e r s ta g e o f flo w e r d e v e lo p m e n t w ou ld te n d to m a k e the
t i s s u e s m o r e s u s c e p t ib le to ic e in o c u la tio n fr o m f r e e z in g te m p e r a tu r e s

104.

(42) w h ic h , in tu rn , w ou ld r e s u lt in m o r e fr u it r u s s e t in g than if f r e e z in g
te m p e r a t u r e s o c c u r r e d la t e r in th e fr u it d e v e lo p m e n t.
S in c e m o s t fu n g ic id e s p r o b a b ly h a v e s o m e p h y to to x ic p r o p e r tie s
(6 3 ), th is p o s s ib le e x p la n a tio n o f th e f u n g ic id e - f r e e z in g te m p e r a tu r e in t e r ­
r e la t io n s h ip d o e s n ot a c c o u n t fo r th e d if f e r e n c e s in fr u it r u s s e t in g r e s u l t ­
in g fr o m th e u s e o f th e v a r io u s c h e m ic a ls .

G ly o d in u se d in th is in v e s t i­

g a tio n h a s b e e n r e p o r te d (28) to h a v e s u r fa c e a c tiv e p r o p e r tie s ; that is ,
it w ill d e c r e a s e th e s u r fa c e te n s io n o f a w a te r m ix tu r e so that a su r fa c e
w h ich i s d iffic u lt to w et, m a y b e c o m e w e tte d w ith th e sp r a y m ix tu r e .
T h e r e c e p t a c le s o f th e a p p le flo w e r in th is stu d y w e r e c o v e r e d w ith a d e n se
m a t o f t r ic h o m e s w h ic h w e r e d iffic u lt to w e t w hen s e c tio n in g , u s in g the
f r e e z in g m ic r o to m e te c h n iq u e .
T h e r e fo r e , b e c a u s e o f it s s u r fa c ta n t p r o p e r ty , g ly o d in m a y be
a b le to w e t th e t r ic h o m e s o f th e flo w e r r e c e p ta c le , p e n e tr a te th is m a t
and c o m e in c o n ta c t w ith th e e p id e r m a l la y e r o f c e i l s o f th e r e c e p ta c le .
T h is w e ttin g p r o p e r ty w ou ld fa c ilit a te th e e n tr y o f the c h e m ic a l into the
s u b - e p id e r m a l la y e r o f c e l l s by p a s s in g b e tw e en th e a n tic lin a l w a lls of
th e c e l l s o f th e e p id e r m is .
A n o th er p o s s ib le e x p la n a tio n o f the v a r ia tio n in fr u it r u s s e t in g
fr o m th e u s e o f d iffe r e n t fu n g ic id e s , m a y be th e d e g r e e o f s o lu b ility o f
th e com p ou n d in a s p r a y m ix tu r e .

C e r ta in p e s t ic id e m a t e r ia ls a r e w e tta b le

105.

p o w d e r s an d a r e c o m p le t e ly in s o lu b le in w a ter; w h e r e a s , o th e r s m a y be
p a r t ia lly s o lu b le o r a p a r t o f th e m o le c u la r str u c tu r e m a y be r e le a s e d into
s o lu tio n a s a s o lu b le m a t e r ia l (8, 4 9 ).

T h e s o lu b ility o r p a r tia l s o lu b ility

o f th e com p ou n d w o u ld f a c ilit a t e the e n tr y in to o r th ro u g h the e p id e r m a l
t i s s u e o f th e fr u it, c a u s in g r u s s e t in g o f c e r ta in v a r ie t ie s .

H o w ev er, the

s c o p e o f th is in v e s tig a tio n w a s not s u ffic ie n t ly e x t e n s iv e o r so d e s ig n e d
to d e te r m in e th is su p p o sitio n .
T h e s lig h t a n a to m ic a l d if fe r e n c e s o b s e r v e d b e tw e e n v a r ie t ie s
e a r ly in th e g r o w in g s e a s o n w hen fr u it r u s s e t in g w a s f i r s t in itia te d , m a k e
it v e r y d iffic u lt to e x p la in w hy s o m e v a r i e t i e s r u s s e t m o r e e a s il y fro m
c o ld in ju r y and c h e m ic a l than o t h e r s .

H o w e v er , th e h is t o lo g ic a l s tu d ie s

( F ig u r e s 15 th ro u g h 2 4 ) su p p o rt the o b s e r v a tio n s by B ell (2) and o th e r s
(24, 3 2 ,5 5 , 57, 58, 60 ) th at a p p a re n t v a r ia tio n s in e p id e r m a l la y e r s o f v a r io u s
v a r i e t i e s do e x is t a s th e g r o w in g s e a s o n p r o g r e s s e s .
T h e r e s u lt s o f th e fr u it r u s s e t in g e x p e r im e n ts in t h is in v e s tig a tio n
in d ic a te d th at G o ld en D e lic io u s w a s th e m o s t s e n s it iv e to e x te r n a l c o n d i­
tio n s th at p r o m o te r u s s e t in g and th e M cIn to sh l e a s t s e n s it iv e w ith Jonathan
b e in g in t e r m e d ia t e .

T h is a p p e a r e d to be c o r r e la t e d w ith the v a r ia tio n in

th e e p id e r m a l la y e r s o f th e th r e e v a r ie t i e s .

T he M cIn to sh h a v in g th e m o s t

c o m p le te e p id e r m a l la y e r at m a tu r ity (F ig u r e 2 0 ) w a s l e s s s u s c e p tib le to
r u s s e tin g ; w h e r e a s , the G o ld en D e lic io u s w ith th e l e a s t d is tin g u is h a b le

106.

e p id e r m is (F ig u r e 17) w a s th e m o s t s u s c e p tib le .

Jonathan (F ig u r e 23) w a s

in t e r m e d ia t e in both r e s p e c t s .
F r o m th is stu d y, it a p p e a r e d that v is ib le d if fe r e n c e s in the e p id e r ­
m a l la y e r o f G o ld en D e lic io u s , Jonathan and M cIn tosh w e r e not d is tin g u is h ­
a b le u n til a p p r o x im a te ly fou r w e e k s a ft e r fu ll b lo o m .

H o w ev er, it w a s

a p p a re n t th a t e x p o s u r e o f th e r e c e p t a c le o f the flo w e r o r fr u it to fr e e z in g
t e m p e r a tu r e s n e a r o r d u rin g b loom r e s u lt e d in m o r e fr u it r u s s e t in g at
h a r v e s t tim e fr o m th e u s e o f s o m e c h e m ic a ls .

T h is a p p a ren t ch a n g e in

th e p r o t e c t iv e c a p a c ity of th e e p id e r m a l la y e r fo llo w in g e x p o s u r e to
f r e e z in g a ir te m p e r a tu r e s ' c o u ld be a r e s u lt o f a c h a n g e in the c h e m ic a l
n a tu r e o f th e in t e r c e llu la r s u b s ta n c e s o f th e e p id e r m a l c e l l s ,

th is

c h e m ic a l c h a n g e o c c u r r in g m o r e r e a d ily in th e e p id e r m a l la y e r o f one
v a r ie t y than a n o th e r .
su c h a p o s s ib ilit y .

T h e r e s u lt s o f th is s e r i e s o f s tu d ie s do s u g g e s t

107.

SUM M ARY

1.

A n in v e s tig a tio n w a s c o n d u cted in 1956 and 1957 at th e M ich ig a n

S ta te U n iv e r s it y H o r tic u ltu r a l fa r m , E a s t L a n sin g , to d e te r m in e th e p o s s ib le
in t e r r e la t io n s h ip b e tw e e n th e o c c u r r e n c e o f f r e e z in g te m p e r a tu r e s n e a r or
d u rin g b lo o m and th e u s e o f c e r ta in p e s t ic id e c h e m ic a ls a s a ffe c tin g fr u it
r u s s e t in g o f a p p le s (M a lu s d o m e s tic a B o r k .).

B ea rin g t r e e s g r o w in g on

M a ilin g VII r o o ts to c k s , o f the v a r i e t ie s G o ld en D e lic io u s and Jonathan
w e r e e x p o s e d to o r p r o te c te d a g a in s t f r e e z in g a ir te m p e r a tu r e s o f 32® F o r
lo w e r by e n c lo s in g th e t r e e s w ith p o ly e th y le n e c o v e r e d c a g e s and u s in g
su p p le m e n ta l e l e c t r i c h e a t.

T he t r e e s w e r e p r u n ed to d iv id e the b e a r in g

s u r fa c e o f e a c h t r e e in to tw o d is tin c t h a lv e s , so that tw o fu n g ic id e t r e a t ­
m e n ts c o u ld be e v a lu a te d in th e s a m e e n v ir o n m e n t.
(a) H a lf - t r e e tr e a tm e n ts o f ca p ta n and g ly o d in w e r e m a d e
on G old en D e lic io u s in 1 9 5 6 .

A t h a r v e s t tim e , th e p o r tio n o f th e tr e e p r o ­

te c te d fr o m f r e e z in g a ir te m p e r a tu r e s and tr e a te d w ith g ly o d in had 2 7 . 8
p e r c e n t o f th e fr u it h e a v ily r u s s e t e d , w h ile the p o r tio n tr e a te d w ith ca p ta n
had no fr u it so a ff e c te d .

On th e t r e e e x p o s e d to te m p e r a tu r e s o f 31. 7 °,

31. 5 °, and 28. 0® F n e a r b lo o m , 84. 5 p e r c e n t o f the fr u it tr e a te d w ith g ly o d in
w e r e h e a v ily r u s s e t e d a s c o m p a r e d to 24. 4 p e r c e n t fo r th e ca p ta n tr e a tm e n t.
(b) T r e a tm e n ts o f g ly o d in at one qu art, and g ly o d in at on e

108.

p in t p lu s fo u r o u n c e s o f P h ygon p e r 100 g a llo n s w e r e m a d e on th e h a lft r e e s o f G o ld en D e lic io u s in 1957 and th e t r e e s w e r e e x p o s e d to v a r y in g
a m o u n ts o f f r e e z in g te m p e r a tu r e s n e a r b lo o m .

At h a r v e s t no fr u its fro m

a n y tr e a tm e n t w e r e f r e e o f r u s s e tin g , but th e s e v e r it y o f th e r u s s e t in g w a s
l e s s fr o m th e u s e o f g ly o d in a t one p in t p lu s P hygon than w hen g ly o d in w a s
u s e d at fu ll s tr e n g th .
(c )

T r e a tm e n ts o f fu ll s tr e n g th captan and g ly o d in w e r e

m a d e on h a l f - t r e e s o f Jonathan in 1 9 5 7 .

At h a r v e s t, 2. 44 p e r c e n t o f th e

fr u it tr e a t e d w ith cap tan and e x p o s e d to 32® F w e r e h e a v ily r u s s e te d , and 19. 51
p e r c e n t lig h tly r u s s e t e d .

T h e g ly o d in tr e a tm e n t had 2. 94 p e r c e n t o f th e fr u it

h e a v ily r u s s e t e d and 4 8 . 53 p e r c e n t lig h tly r u s s e t e d .

An e x p o s u r e o f 2 7 . 5® F

in c r e a s e d v e r y s lig h t ly th e am ou n t o f h e a v ily r u s s e t e d fr u it fro m th e u s e o f
g ly o d in tr e a tm e n t a s c o m p a r e d to an e x p o s u r e o f 32® F .

E x p o s u r e s to m in im u m

te m p e r a tu r e s o f 27. 5®, 30. 5®, 31. 5® and 30. 5® F n e a r b lo o m r e s u lt e d in 15. 52
p e r c e n t o f th e fr u it h e a v ily r u s s e t e d , and 4 6 . 55 p e r c e n t lig h tly r u s s e t e d fo r the
cap tan tr e a tm e n t, and 6 7. 07 p e r c e n t o f th e fr u it h e a v ily r u s s e t e d and 2 8 . 05
p e r c e n t lig h tly r u s s e t e d fr o m th e u s e o f g ly o d in .
2.

A m ix e d b lo c k o f 1 6 - y e a r - o ld G o ld en D e lic io u s , Jonathan and

M cIn to sh a p p le t r e e s lo c a te d at th e M ich ig a n S tate U n iv e r s it y G raham E x p e r i­
m e n t S tation , G ran d R a p id s, w a s u s e d to e v a lu a te th e e f f e c t s o f captan , th ira m ,
g ly o d in , and ca p ta n fo llo w e d by g ly o d in a fte r f ir s t c o v e r on fr u it r u s s e tin g .

109.

T h e t r e a tm e n ts w e r e a p p lie d w ith a c o m m e r c ia l s p r a y e r w ith an a ir - b l a s t
a tta c h m e n t.
m e n t.

A low o f 3 0. 5° F o c c u r r e d at th e e a r ly - p in k s ta g e o f d e v e lo p ­

T h e r e w e r e no s ig n ific a n t d if fe r e n c e s o f fr u it r u s s e t in g b etw een

tr e a tm e n ts.
3.

A s e c o n d b lo c k a t the G raham E x p e r im e n t S ta tio n c o n ta in in g

7 - y e a r - o l d M cIn to sh and Jonathan a p p le t r e e s w a s d iv id e d so a s to c o m p a r e
th e in flu e n c e o f fe r b a m , g ly o d in and th ira m w ith that o f captan on fr u it
r u s s e t in g .

In 1957, th e stu d y w a s r e p e a te d , e x c e p t that w e tta b le su lfu r

w a s s u b s titu te d fo r fe r b a m .

A ll tr e a tm e n ts w e r e a p p lie d w ith a c o m m e r ­

c ia l s p r a y e r w ith an a i r - b l a s t a tta ch m en t.
(a) In 1956, a m in im u m te m p e r a tu r e o f 30. 5® F w a s r e c o r d e d
a t th e tim e o f e a r ly p in k .

At h a r v e s t, no s ig n ific a n t d if fe r e n c e s o f h e a v y

r u s s e t in g w e r e n o ted e it h e r b e tw e e n tr e a tm e n ts o r b e tw e e n v a r i e t i e s .

H ow ­

e v e r , one grou p o f t r e e s of th e ca p ta n tr e a tm e n t w a s lo w e r in e le v a tio n than
th e o th e r t r e e s , and t h e s e t r e e s did h a v e a la r g e r am ount o f lig h tly r u s s e t e d
fr u it th an th e o th e r p lo t s .
(b) In 1957, m in im u m te m p e r a tu r e s o f 3 1 .5 ° , 31.0® and
31. 5® F w e r e r e c o r d e d n e a r th is e x p e r im e n t.

S ig n ific a n t d if fe r e n c e s fo r

h e a v ily r u s s e t e d fr u it s did o c c u r b e tw e en sp r a y tr e a tm e n ts u s e d on Jonathan.
T h e r e w e r e s ig n ific a n t d if f e r e n c e s in th e am ount o f h e a v ily r u s s e t e d fr u its
b e tw e e n th e g r o u p s o f t r e e s tr e a te d w ith captan, th e r a n g e b e in g 12. 1 p e r c e n t

110.

to 2 1. 6 p e r c e n t .

T h is i s c o m p a r e d to 12. 4 p e r c e n t h e a v y r u s s e t in g fo r

th e s u lfu r tr e a tm e n t, 18. 0 p e r c e n t fo r the th ira m tr e a tm e n t, and 29. 5 p e r ­
c e n t fo r th e g ly o d in tr e a tm e n t.

T h e cap tan tr e a tm e n t h a v in g the 21. 6 p e r ­

c e n t h e a v ily r u s s e t e d fr u it w a s lo w e r in e le v a t io n than th e o th e r tr e a tm e n ts .
T h e e x c e s s i v e r u s s e t in g c o u ld be a s s o c ia t e d w ith lo w e r a ir te m p e r a tu r e s
in th e l e s s fa v o r a b le e le v a t io n .

T h e r e i s s o m e e v id e n c e ,

not a p a r t of

th is s e r i e s o f s tu d ie s , to in d ic a te th at the e x c e s s i v e h ea v y r u s s e t in g fr o m
th e u s e o f g ly o d in c o u ld h a v e r e s u lt e d fro m th e u s e o f Phygon w ith th e
g ly o d in a ft e r th e o c c u r r in g f r e e z in g te m p e r a tu r e s , and not to g ly o d in a lo n e .
N o s ig n ific a n t d if f e r e n c e s w e r e found b e tw e en tr e a tm e n ts w ith r e s p e c t to
lig h t r u s s e t in g .
(c)

T he s a m e w e a th e r c o n d itio n s and s p r a y tr e a tm e n ts on

M cIn to sh r e s u lt e d in no s ig n ific a n t d if f e r e n c e s b e tw e e n tr e a tm e n ts .
4. C o m p a r in g th e r e s u lt s o f the tw o s e a s o n s fo r th e v a r i e t i e s
M cIn to sh and Jonathan w hen th e s a m e fu n g ic id e tr e a tm e n ts and m e th o d o f
a p p lic a tio n w e r e u se d , th e r e w a s a s ig n ific a n tly h ig h e r a m o u n t o f r u s s e t ­
in g in 1957 than in 1956.

T e m p e r a t u r e s o f 31. 5®, 31. 0® and 31. 5° F w e r e

r e c o r d e d n e a r b lo o m in 1957, w h e r e a s a m in im u m o f 30. 5 F w a s r e c o r d e d
p r io r to b lo o m in 1956.
5. H is t o lo g ic a l s tu d ie s w e r e c o n d u cted in 1956 fo r th e p u r p o se of
(1) d e te r m in in g th e d if f e r e n c e s in d e v e lo p m e n t o f th e c u t ic le and e p id e r m a l

t i s s u e o f th e v a r i e t i e s G o ld en D e lic io u s , Jonathan and M cIntosh; and
(2) d e te r m in in g how and w h en fr u it r u s s e t in g o f G old en D e lic io u s d e v e lo p s
w h en c e r t a in p e s t ic id e c h e m ic a ls a r e u s e d p r io r to s e c o n d c o v e r .

F rozen

s e c t io n s s ta in e d w ith Sudan IV and k ille d and fix e d m a t e r ia l d iffe r e n tia lly
s ta in e d w ith s a fr a n in and fa s t g r e e n w e r e u s e d fo r th e s e s tu d ie s .
(a) T h e f i r s t m ic r o s c o p ic s ig n s o f r u s s e t fo r m a tio n on
G o ld en D e lic io u s w e r e o b s e r v e d th r e e w e e k s a fte r fu ll b loom a s s m a ll
n u m b e r s o f ir r e g u la r ly p r o lif e r a tin g c e l l s in th e o u te r c o r t ic a l la y e r .

At

fo u r w e e k s a ft e r fu ll b lo o m , th e s e p r o lif e r a tin g c e l l s had ru p tu red the
e p id e r m is and c u t ic le .

T h is in itia l p r o lif e r a tio n w a s p r e su m a b ly s tim u ­

la te d e it h e r by in ju r y to the o u te r c o r t ic a l c e l l s by f r e e z in g te m p e r a tu r e s ,
th e u s e o f c e r t a in fu n g ic id e c h e m ic a ls w h ich ,

in turn, c a m e in c o n ta c t

w ith the o u te r c o r t ic a l la y e r o f c e l l s , o r a co m b in a tio n o f the two fa c to r s .
A s g ro w th o f th e fr u it con tin u ed , m o r e s u b -e p id e r m a l p r o lif e r a ­
tio n o c c u r r e d and at h a r v e s t tim e a v e r y e v id e n t p h e llo g e n w a s found below
the r u s s e t e d a r e a s .
(b) T h e in itia l r u p tu r e s o f th e e p id e r m a l la y e r co u ld not be
a s s o c ia t e d w ith e it h e r th e t r ic h o m e s o r sto m a ta b e c a u s e the f i s s u r e s w e r e
m o r e n u m e r o u s th an the to ta l n u m b e r s o f tr ic h o m e s and sto m a ta .

A lso ,

the in n e r e x p o s e d s u r f a c e s o f th e in itia l r u p tu r e s w e r e not c o v e r e d by a
c u t ic le .

A c tu a l r e m o v a l o r in ju r y o f th e tr ic h o m e s w ith d ry ic e at v a r io u s

s t a g e s o f flo w e r d e v e lo p m e n t did not c a u s e r u s s e t fo r m a tio n .

(c) M ic r o s c o p ic s tu d ie s o f th e d e v e lo p m e n t o f th e p r o t e c t ­
iv e l a y e r s o f th e G o ld en D e lic io u s , Jonathan and M cIn to sh v a r ie t ie s r e v e a le d
th at a t th e tim e th e f lo w e r s e m e r g e fro m bu ds, th e r e c e p t a c le w a s not
c o v e r e d w ith a c u t ic le .

H o w e v e r , s o m e fa tty s u b s ta n c e s w e r e found w ith in

th e e x p o s e d c e l l - w a l l s o f th e e p id e r m a l c e l l s p r io r to fu ll b lo o m .

C u tic u la r -

iz a t io n o c c u r r e d f i r s t a t th e b a s e s o f th e tr ic h o m e s and te n to fo u r te e n d a y s
a ft e r fu ll b lo o m , th e c u t ic le w a s c o m p le te on th e e p id e r m a l s u r fa c e o f the
fr u it.
(d) T h e d e v e lo p m e n t o f th e p r o te c tiv e la y e r s o f th e v a r ie t ie s
G o ld en D e lic io u s , Jonathan and M cIn to sh w a s s im ila r u n til a p p r o x im a te ly 30
d a y s a f t e r fu ll b lo o m at w h ich tim e c u tic u la r p e g s w e r e found to be f illin g
th e c a v it ie s in th e e p id e r m a l la y e r o f G o ld en D e lic io u s c r e a te d by th e s e p a r ­
a tio n o f e p id e r m a l c e l l s a s the fr u it e n la r g e d .
Jonathan and M c In to sh v a r ie t ie s *

T h is w a s l e s s e v id e n t in the

At h a r v e s t m a tu r ity , a d is tin c t,

e p id e r m a l la y e r c o u ld not be found in G old en D e lic io u s .

in ta c t

By c o n tr a s t, the

e p id e r m a l la y e r o f th e M cIn to sh w a s v e r y e v id e n t and no s e p a r a tio n o f e p i­
d erm al c e lls w as ob served .

T h e e p id e r m a l la y e r o f Jonathan, alth ough

d is c e r n a b le , w a s not a s r e g u la r a s in th e M cIn tosh .

113.

L IT E R A T U R E C IT E D

1. B aker, C. E. A stu d y o f th e sk in s tr u c tu r e o f the G r im e s a p p le a s a f f e c t ­
e d by d iffe r e n t ty p e s o f in ju ry . P r o c . A m e r . S o c. H ort. S c i. 27: 7 5 8 1 . 19 3 0 .
2 . B ell, H. P. T h e p r o t e c t iv e la y e r s o f th e a p p le.
3 9 1 -4 0 2 . 1937.

Can. Jour. R e s . 15c:

3. ___________. T h e o r ig in of r u s s e t in g o f th e G o ld en R u s s e t a p p le. C an. Jour.
R e s . 15c: 5 6 0 -5 6 6 . 1937.
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_____ - T h e o r ig in and h is to lo g y o f b o r d e a u x sp r a y r u s s e t in g on the
a p p le . C an. Jour. R e s . 19c: 4 9 3 -4 9 9 . 1941.

5. B lack, C a r o lin e A . T h e n a tu re o f th e in f lo r e s c e n c e and fr u it o f P y ru s
m a lu s . M em . N ew Y o rk Bot. G a rd . 6: 5 1 9 -5 4 7 . 1916.
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1931.
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R e in h o ld P u b lish in g

M inn. H ort. 46: 4 1 5 -4 1 6 .

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M cG raw H ill Book C om pany, Inc. , N ew Y o rk and L ondon. 1925.

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T he

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M c G r a w -H ill Book C om pany,

2 8 . K r etch m a n , D . W. , and A. E . M itc h e ll. E v a lu a tio n o f th e s u r fa c e
a c t iv e p r o p e r t ie s o f g ly o d in u s in g 2, 4 -d ic h lo r o p h e n o x y a c e tic a c id
and le a f p r in ts . M ich . A g r . E xp. Sta. Q uart. Bui. 40(1): 1 5 4 -1 6 1 .
1957.
2 9 . M a c D a n ie ls , L. H. , and A. J. H e in ic k e . T o w hat e x te n t i s s p r a y burn o f a p p le fr u it c a u s e d by f r e e z in g o f th e flo w e r s . Phytopath.
20: 9 0 3 -9 0 6 . 1930.
30. _____________________ , and F . F . C o w a rt. T h e d e v e lo p m e n t and s tr u c tu r e
o f th e a p p le le a f. N. Y . A g r . E xp . Sta. C o r n e ll M em . 2 5 8 . 1944.
31. M e r ic le , L. W . , and W. G. W h a ley . C e ll- w a ll s tr u c tu r e o f a p ic a l
m e r is t e m s . Bot. G az. 114: 3 8 2 -3 9 2 . 1952.
32. M e y e r , A . A stu d y o f the sk in s tr u c tu r e o f G o ld en D e lic io u s a p p le s .
P r o c . A m e r . S o c. H ort. S c i. 45: 1 0 5 -1 1 0 . 1944.
33. M itc h e ll, A . E . Do o r g a n ic c o m p o u n d s p a y - o ff in th e a p p le s p r a y in g
p r o g r a m ? P r o c . M ich . State H o rt. S oc. 81: 2 0 - 2 4 . 1951.
34.
P r o c . V a.

. F r u it fin is h , c o n c e n tr a te s p r a y in g and r e la t e d p r o b le m s .
S ta te H o rt. S o c ., and A m e r . P om . S o c. 40: 1 2 3 -1 2 7 . 1952.

35.

. U n p u b lish ed in fo r m a tio n on fr u it fin is h s tu d ie s .
S tate U niv. D e p t. H ort. 1 9 5 3 -1 9 5 6 .

36.

. N ew s p r a y c h e m ic a ls fo r a p p le s and th e ir p la c e in the
1954 s p r a y in g c a le n d a r . P r o c . M ich . S tate H ort. S oc. 83: 3 1 -3 3 . 1953.

m a t e r ia ls .

M ich .

A p p le s p r a y i n g p r o b le m s and th e s e le c t io n o f sp r a y
P r o c . M ich . S tate H ort. Soc. 84: 14 -1 8 and 8 5 -8 7 . 1954.

116.

38.

M itc h e ll, A . E . How w e a r e g r o w in g b e tte r a p p le s in M ich ig a n .
N. Y . S ta te H ort. S o c. 99: 9 4 -9 8 .
1954.

3 9 *___________________• P e r fo r m a n c e o f s p r a y c h e m ic a ls in 1955.
S ta te H o rt. S oc. 85: 1 1 1 -1 1 4 . 1955.

P roc.

P r o c . M ich .

4 0 * _________________ * A. C. D ow dy, E. J. K lo s, and R. H. F u lto n .
S p r a y in g c a le n d a r . M ich . S tate U niv. E xt. Bui. 154. 1957.

1957

__________________ *_ and D. W. K r etch m a n . F r u it r u s s e t in g o f Jonathan
and it s r e la t io n to c o ld and sp r a y c h e m ic a l in ju ry in M ic h ig a n in 1 9 5 7.
P r o c . M ich . S ta te H ort. S oc. 87: 5 9 -6 4 . 1957.
42.

M o d lib o w sk a , I . , and W. S. R o g e r s . F r e e z in g o f p la n t t i s s u e s un der
the m ic r o s c o p e . Jour. E xp. Bot. 6(18): 3 8 4 -3 9 6 .
1954.

4 3. M o r s e , W. J. A p p le s p r a y in g e x p e r im e n ts in 1916 and 1917.
A g r . E xp . Sta. Bui. 271: 1 0 1 -1 2 8 .
1918.
44.

M e.

M u e lle r , L. E . , P. H. C a r r, and W. E . L o o m is . T h e s u b - m ic r o s c o p ic
s tr u c tu r e o f p la n t s u r f a c e s . A m e r . Jour. Bot. 41: 5 9 3 -6 0 0 . 1954.

4 5 . O r g e ll, W . H. T h e is o la t io n and p e r m e a b ilit y o f p la n t c u tic le .
T h e s is . U n iv e r s it y o f C a lifo r n ia . 1943.

Ph. D .

46. P alm ite r , D. H. R e la tio n o f sp r a y m a t e r ia ls to r u s s e t in g o f D e lic io u s
and G old en D e lic io u s a p p le s . P r o c . A m e r . S o c. H ort. S c i. 45: 1 1 3 118. 1944.
4 7 . _________________ , a n d R . M. S m o ck . E ffe c t o f fu n g ic id e s on M cIn to sh
a p p le y ie ld and q u ality: A f i v e - y e a r stu d y u n d er H u d son V a lle y
c o n d itio n s , 1 9 4 9 -1 9 5 3 . N . Y . A g r . E xp. S ta . G en ev a Bui. 767: 1 -4 0 .
1954.
48.

. S p ra y in ju r y to a p p le s in 1957.
Q u art. Bui. 24(1): 2 . 1958.

N. Y . A g r . E xp. Sta.

49. P e s t ic id e O ffic ia l P u b lic a tio n and c o n d e n se d data on p e s t ic id e c h e m ic a ls .
A s s o c , o f A m e r . P e s t i c i d e C o n tro l O ffic ia ls , Inc. 191 p a g e s . 1955.
5 0 . P r ie s t ly , J. H.
1943.

T h e c u tic le o f A n g io s p e r m s .

Bot. R ev . 9: 5 9 3 -6 1 6 .

117.

51.

R a s m u s s e n , E . J.E ffe c t o f s p r a y m a t e r ia ls on fin is h
and k e e p in g
q u a lity o f a p p le s .
M ich . A g r . E xp. Sta. Q uart. Bui. 25(3): 2 6 3 -2 7 1 .
1943.

52* _____ ________________ , W. T o e n je s , and F . C. S tro n g . E ffe c t o f sp r a y
tr e a tm e n t on f o lia g e in ju ry , p e s t c o n tr o l, and y ie ld and q u a lity of
a p p le s . M ich . A g r . E xp. Sta. S p ec. Bui. 347: 1 -2 6 .
1948.
53.

R o se n , H. R. Low te m p e r a tu r e in ju r y o f a p p le b lo s s o m s and s c a r c it y
o f b lig h t in A r k a n s a s in 1936. P lant D is . R p tr. 20: 1 9 5 -1 9 6 . 1936.

54. S h a r v e lle , E . G. E ffe c t o f s u m m e r fu n g ic id e s on th e fin is h o f r u s s e t s e n s it iv e a p p le s . P lan t D is . R p tr. 37(4): 2 3 2 -2 3 4 . 1953.
5 5. S im o n s, R. K. F r o s t in ju r y on G old en D e lic io u s a p p le s - - m o r p h o lo ­
g ic a l and a n a to m ic a l c h a r a c t e r is t ic s o f r u s s e t e d and n o r m a l t is s u e .
P r o c . A m e r . S o c. H ort. S c i. 69: 4 8 - 5 5 . 1957.
56. S k o ss , J e s s e D . T h e s tr u c tu r e and c h e m is t r y o f the p la n t c u tic le in
r e la t io n to e n v ir o n m e n ta l f a c t o r s an d to p e r m e a b ilit y . Ph. D. T h e s is
U n iv. S ou th ern C a lifo r n ia , L o s A n g e le s . 1953.
57. T e t le y , U. A stu d y o f th e a n a to m ic a l d e v e lo p m e n t o f th e a p p le and s o m e
o b s e r v a t io n s on th e " p e c tic c o n s t it u e n t s ” o f the c e l l - w a l l s . Jour. P om .
H o rt. S c i. 8: 1 5 3 - 1 7 2 . 1930.
58.

. T h e m o r p h o lo g y and c y to lo g y o f th e a p p le fr u it w ith s p e c ia l
r e f e r e n c e to th e B r a m le y ’s S e e d lin g v a r ie t y . Jour. P o m . H o r t. S c i. 9:
2 7 8 -2 9 7 . 1931.

59. T u k ey, H. B. , an d J. O. Y ou n g. G r o s s m o r p h o lo g y and h is to lo g y o f d e v ­
e lo p in g fr u it o f th e a p p le . Bot. G a z. 104(1): 3 -2 5 . 1942.
6 0 . V e r n e r , L . H is to lo g y of a p p le fr u it t is s u e in r e la t io n to c r a c k in g .
A g r . R e s . 57(11): 8 1 3 -8 2 4 . 1 938.

Jour.

6 1. W ein trau b , R. L. , J. N. Y ea tm a n , J. W. Brown, J. A . S k o ss, and
J. R. C o n o v e r . S tu d ie s on e n tr y o f 2, 4 -D in to l e a v e s . P r o c . 8th N. W.
W e ed C o n tro l C onf. p. 5 - 1 1 . 1954.

118.

6 2 . W h a ley , W. G . , L . W. M e r ic le , and C. H e im is c h . T he w a ll of the
m e r is t e m a t ic c e l l . A m e r . Jour. Bot. 39: 2 0 -2 6 . 1952.
6 3 . Y oun g, H. C. , and R . C. W alton .
15(7): 4 0 5 -4 1 5 . 1925.

S p ray Injury to a p p le.

Phytopath.

64. Z sc h o k k e , A . U b e r den Bau der Haut und d ie U r sa c h e n d er v e r s c h ie d e n e r
H a ltb a r k e it u n s e r e K e r n o b stfr lic h te . L a n d w irt. Jahrb. d e r S c h w e iz .
Bot. II. p. 153. 1897.

119

APPEN D IX A

E x p la n a tio n o f T e r m in o lo g y

C e r ta in te r m in o lo g y u s e d in th is p a p e r h a s b e e n u s e d in c ite d
lit e r a t u r e w ith any o f s e v e r a l d iffe r e n t c o n n o ta tio n s .

T h e r e fo r e , fo r c l a r ­

ific a tio n a s to th e ir m e a n in g , a l is t in g o f t e r m s and a b r ie f d e s c r ip t io n o f
th e ir m o r e a c c e p te d u s e w ill fo llo w :
A.

T e r m in o lo g y u s e d in s e q u e n c e o f fr u it d e v e lo p m e n t o f a p p le, ta k en
fr o m M a c D a n ie ls e t a l. (30) and M itc h e ll et^aT (40):
1) D o r m a n t - fr u it in g buds c o m p le t e ly e n c lo s e d by bud s c a l e s .
2) D e la y e d d o rm a n t - bud s c a l e s and s e v e r a l s c a l e - l i k e l e a v e s a r e
sh e d and b a s a l sp u r le a v e s a r e fla t in th e bud e n c lo s in g th e r e c e p ­
t a c le o f th e flo w e r .
3) E a r ly p r e - p in k o r c lu s t e r bud s ta g e - c o r o lla c o m p le t e ly c o v e r e d
by s e p a ls and th e r e c e p t a c le s t i l l s o m e w h a t e n c lo s e d by e x p a n d in g
le a v e s .
4) P r e -p in k - sp u r l e a v e s m o s t ly u n r o lle d and b lo s s o m s h e ld to g e th e r
by e n ta n g lin g o f th e t r ic h o m e s in a c lu s t e r w ith th e r e c e p t a c le
exp osed .
5) P in k - in d iv id u a l b lo s s o m s s e p a r a te d w ith in a c lu s t e r and a ll b lo s s o m s
h a v in g e x p o s e d , but c lo s e d p e t a ls .

6) F u ll b lo o m - a m in im u m o f th r e e -fo u r th s o f the b lo s s o m s in a ll
c l u s t e r s on th e t r e e u n fo ld ed w ith a ll p a r ts e x p o s e d .
7) P e ta l fa ll - t h r e e - f o u r t h s o f th e p e ta ls fa lle n fro m a ll th e c lu s t e r s
on the t r e e .
8) F i r s t c o v e r - s e v e n to te n d a y s a fte r p e ta l fa ll.
9) S e c o n d c o v e r - th r e e w e e k s a fte r fu ll b lo o m .

T e r m s r e la t iv e to a n a to m y o f the p r o te c tiv e la y e r s o f th e fr u it a s d e s ­
c r ib e d by O r g e ll (45) and E a m e s and M a cD a n ield (12) and h a v e b een
m is in t e r p r e t e d in p a s t lite r a tu r e :
1) C u tic le - c o n s is t s o f on e o r m o r e la y e r s o f s e m i- lip o id a l m a te r ia l
e x t e r io r to th e o u te r e p id e r m a l c e l l w a ll that in c lu d e s cu tin la y e r s
and w a x e n c r u s ta tio n s .
2) C u tic u la r iz a tio n - th e p r o c e s s o f c u tic le fo r m a tio n .
3) C u tic u la r s k ir t s o r f la n g e s - the p r o je c tio n s o f th e c u tic le b etw een
th e a n tic lin a l e p id e r m a l c e l l w a lls .

T h e s e fla n g e s a r e o ften c a lle d

" p e g s ” w hen o b s e r v e d in c r o s s - s e c t i o n .
4) C utin - th e s e m i- lip o id a l p o ly m e r w h ich c o n s titu te s the m a tr ix and
u s u a lly th e b u lk of th e c u tic le .

Its c h e m ic a l n atu re is p o o r ly u n d e r ­

s to o d and it m a y be im p r e g n a te d o r o v e r la in w ith w ax o f v a r io u s
fo r m s .

121

5) C u tin iz a tio n - th e p r o c e s s o f c u tin im p r e g n a tio n o f c e l l w a lls ; p a r t i­
c u la r ly th e e p id e r m a l c e l l w a lls .
6) P h e llo g e n - th e m e r is t e m a t ic c o r k c a m b iu m .
7) P h e lle m - c o r k y t is s u e p r o d u c e d c e n tr ifu g a lly fr o m th e p e llo g e n .
8) P h e llo d e r m - the th in -w a lle d c e l l s p r o d u ce d in te r n a lly by a p h e l­
lo g e n .
9) P e r id e r m - th e c o lle c t iv e te r m a p p lie d to the p h e llo g e n , p h e lle m
and p h e llo d e r m .

122

APPEN D IX B
C h e m ic a l n a tu r e o f s p r a y m a t e r ia ls d is c u s s e d in th is in v e s tig a tio n .
1) A r a m ite - 2 -( p -te r t-b u ty lp h e n o x y ) i s o p r o p y l- 2 - c h l o r o - e t h y l s u lf it e .
2) C aptan - N - t r ic h lo r o m e t h y lm e r c a p t o - 4 , 4 - c y c l o h e x e n e - 1, 2 - d i c a r b o x im id e .
3) D D T - 1, 1, l - t r i c h l o r o - 2 , 2 -b is (p ~ c h lo r o p h e n y l) e th a n e .
4) EPN - O -e th y l-O -p -n itr o p h e n y l b e n z e n e e th io p h o s p h a te .
5) F e r b a m - f e r r ic d im e th y ld ith io c a r b a m a te .
6 ) G ly o d in - 2 -h e p ta d e c y lg ly o x a lid in e a c e t a t e .
7) M a la th io n - S - ( l , 2 -d ic a r b o x y e th y l), O, O -d im e th y l d ith io -p h o s p h a te .
8) M e th o x y c h lo r - 1, 1, l - t r i c h l o r o - 2 , 2 - b i s (p -m e th o x y p h e n y l)e th a n e.
9) O v o tra n - p - c h lo r o p e h n y l-p -c h lo r o b e n z e n e s u lfo n a te .
10) P a r a th io n - O, O -d ie th y l, O -p -n itr o p h e n y l th io p h o sp h a te .
11) P h ix - P h e n y lm e r c u r ic a c e t a te .
12) P hygon - 2, 3 - d i c h l o r o - l , 4 - n ap h th oquinone.
13) T h ir a m - te tr a m e th y lth iu r a m d is u lfa te .
14) T r ito n B 1956 - a p h th a lic g ly c e r o l a lk y d r e s in ,
fa c ta n t o n ly ).

(u se d a s a s u r ­