THE EFFECTS OF DE-ICING SALT SPRAY
ON HIGHWAY PLANTINGS‘ .

Thesis for the Degree of M. 8..
MICHIGAN STATE UNIVERSITY
LUTHER MOXLEY
1973

ABSTRACT
THE EFFECTS OF DE-ICING SALT SPRAY ON HIGHWAY PLANTINGS:
SURVEY OF INJURY ALONG MICHIGAN HIGHWAYS AND

STUDIES ON THE SODIUM AND CHLORINE CONTENT
OF AUSTRIAN AND WHITE PINE

BY

Luther Moxley

Reports of de-icing salt spray injury to plants has in-
creased in the past decade (45,59,78). This study was under-
taken to observe salt spray injury to plants bordering
selected Michigan highways in order to provide a comprehensive
guide to salt spray tolerant plants for highway areas and to
partially delineate the reasons for the tolerance of Austrian
pine and the susceptibility of white pine to salt spray.

Results of the survey indicate that those plants with '
thick coatings of wax on foliage, stems, and buds were most
tolerant to salt spray. Those plants with pubescent coatings
on the stems, buds and foliage were also tolerant. Injury
from salt spray was observed on plants as far as 250 feet
from the edge of the highway and to a vertical distance of
20 feet.

Microprobe analysis results indicate that sodium and

chlorine is less evenly distributed on the white pine needle

surface. The results of cross section analysis indicate that

Luther Moxley

the tolerance of Austrian pine is not due to the fact that it
is able to exclude sodium and chlorine from the needle cells.
Tolerance of Austrian pine may be related to its ability to

tolerate higher levels of sodium and chlorine in the cells or

its ability to resist dessication.

THE EFFECTS OF DE-ICING SALT SPRAY ON HIGHWAY PLANTINGS:
SURVEY OF INJURY ALONG MICHIGAN HIGHWAYS AND
STUDIES ON THE SODIUM AND CHLORINE CONTENT
OF AUSTRIAN AND WHITE PINE

BY

Luther Moxley

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Horticulture

1973

ACKNOWLEDGMENTS

Sincere appreciation is extended to Drs. H. Davidson
and H. P. Rasmussen for their guidance and assistance in
this work.

The technical assistance of Mr. Vivion Shull on the

microprobe is also greatly appreciated.

 

ii

LIST OF TABLES. . . .

LIST OF FIGURES . . .

INTRODUCTION. . . . .
LITERATURE REVIEW . .

De-icing Salt. .
What is it?

How does salt .
Salts in the Highway Environment
Salts in the Water Supply

TABLE

OF CONTENTS

 

O O O

Salts in the Soil
Salts as Spray. .
Effects of Salt on Plants.

Soil Salts.
Salt Spray.

work?

Salt Tolerance, Avoidance,

Injury. . .
Soil Salts.
Salt Spray.

MATERIALS AND METHODS

Preliminary Survey

I-96 Survey. . .
M-78 surveYo o o
I-496 Survey . .

Michigan Arboretum Survey.

0 o o

O 0 0

Microprobe Analysis of White
Needle Surfaces .
Microprobe Analysis of White
Needle Cross Sections

RESULTS AND DISCUSSION.

Preliminary Survey . .

I-96 Survey. . .

iii

9
an
o

d A

00.00.0000.

P“

OOOHOOOOOOOOI.

0 Q o o o
Austrian Pine
0 O O 0 O I O

Austrian Pine

Page

vi

36
36
39
4Q
40
41
41
43
44

44
45

TABLE OF CONTENTS-~Continued Page

M-78 surveYo o o o o o o o o o o o o g o c o o o o 45
1-496 survey 0 o o o o o o o o o o o o g o g o o o 48

Michigan Arboretum Survey. . . . . . . . . . . . . 51
Microprobe Analysis of White and Austrian Pine

Needle Surfaces . . . . . . . . . . . . . . . 51
Microprobe Analysis of White and Austrian Pine

Needle Cross Sections . . . . . . . . . . . . 56

SUMMARYANDCONCLUSIONS................ 59
LITERATURE CITED 0 O O O O O O O 0 O O O O O I O O O O O 6 5

APPENDIX--Salt Tolerances of Various Woody and Herba—
ceous Plants. . . . . . . . . . . . . . . . . 73

References. . . O O O . O O O C O O O O Q C O 88

iv

TABLE

LIST OF TABLES

Page

De-icing salt additives. . . . . . . . . . . . . . 5

Average salt spray injury ratings of plants bor-
dering 1-96--May 1972. o o o o o o o o o o o o o o 47

Average salt spray injury ratings of evergreens
observed on M-78--March 1973 . . . . . . . . . . . 49

Average salt spray injury ratings of plants
observed on I-496--April 1972 and April 1973 . . . 50

Average salt spray injury ratings of plants at the
Michigan Arboretum--l972 and 1973. . . . . . . . . 52

Average salt spray injury ratings and tolerances
of plants bordering selected Michigan highways . . 60

LIST OF FIGURES

FIGURE

Fate of salts in the highway environment. . . . .

Salt injury survey areas in the Lansing-East
LanSing ViCinj-ty O O O O O O O O O O O O O O O O 0

Salt injury survey area-—Ford Motor Company's
MiChigan AIboretumO O O O O O O Q 0 O O O O O O O

Tufting of the branches of bur oak (Quercus
macrocarpa) . . . . . . . . . . . . . . . . . . .

Representative relative X-ray intensities of
sodium and chlorine on white pine needle surfaces

Representative relative X-ray intensities of
sodium and chlorine on Austrian pine needle sur-

faces 0 O O O O O O O O O O O O I O O O O O O O 0

Representative relative X-ray intensities of
sodium and chlorine in white pine needle cross
seCtionS O O O O O I O O O O O O O O O O O O O O 0

Representative relative X-ray intensities of

sodium and chlorine in Austrian pine needle cross
sections 0 O O O O O O O O O O O O I O Q O O I O 0

vi

Page

18

37

42

46

54

55

57

58

INTRODUCTION

The use of de-icing salts has increased in the last
decade as man's desire to travel by automobile over great
distances at high speeds has increased. Westing (95) reports
that in 1968 six million tons of salt were applied to high-
ways in the northern states; 95% being applied as NaCl and
5% as CaClz. A typical New England highway received as much
as twenty tons of salt per mile per season. westing indi-
cates that salt use is increasing at the rate of one million
tons per year. Estimates of salt use in the northern states
in the 1968-69 winter have been as high as ten million tons
(68).

The problem of plant injury from salts has received much
attention in recent years but is a problem that has been
recognized for some time. Wyman (99) notes that when
Forsythia was brought by ship from the Orient to Europe in
the 1800's, protection from salt spray was provided. In the
early twentieth century calcium chloride used as a dust pal-
liative on dirt roads was found to injure plants along these
roads (85,87,88,90). In more recent years much damage has

been reported from salts applied to highways as de-icers

(1,22,36,39,42,50,56,74,83).

The purpose of this research is to observe de-icing salt
spray injury to plants along Michigan highways and to par-
tially delineate the reasons for the varying susceptibility
of white pine (Pings strobus) and Austrian pine (Pings gigrg).
It is hoped that this work will provide a comprehensive guide
to salt spray tolerances of several plant species and will aid
in the understanding of the phenomenon of salt spray toler-

ance o

LITERATURE REVIEW

De-icing»Salt
What is it?

Today, the terms "road salt" and "de-icing salt" include
more than just sodium chloride or calcium chloride. De-icing
salts or road salts are combinations of sodium chloride
and/or calcium chloride and various additives.

The major portions of de-icing salts still consist of
sodium chloride and calcium chloride; sodium chloride being
more widely used because of its lower cost and greater avail—
ability. Sodium chloride is generally applied in the form of
the mineral halite which is 94 to 97% sodium chloride (80).
Sodium chloride (NaCl) has a molecular weight of 58.45 and
is comprised of 39.34% Na and 60.66% Cl. It occurs as cubic
white crystals, granules, or powder. NaCl is colorless and
transparent being translucent only when in large crystals.
NaCl has a density of 2.17, a melting point of 804°C, and a
solubility in cold water of 35.79/100 cc (86,92). Its
eutectic temperature (lowest possible freezing point of a
Saturated solution) is -6‘F. NaCl has a heat of solution of
-l.18kC/mole. It is usually most effective as a de-icer at

temperatures above 20°F (80).

Calcium chloride (CaClz) is a joint product of natural
salt brines and can exist in anhydrous, mono-, div, tetra-,
and hexahydrate forms. CaCl2 has a moledular weight of 110.99
and contains 36.11% Ca and 63.89% C1. The hexahydrate form
(CaC12.6H20) exists as deliquescent, trigonal crystals and
has a melting point of 30°C. The density of CaCl is 2.15

2
and its solubility in cold water is 74.5g/100cc (86,92).
Calcium chloride has a eutectic temperature of —67°F and a
heat of solution of 3.01kC/mole. CaCl2 is sometimes used as
a de-icer when temperatures fall below 10°F. It is often
used in combination with NaCl. Its use is not as great as
that of NaCl because of its high cost. In Wisconsin, for

example, only 5% of the de-icing salt applied is CaCl (80).

2

Several additives other than sodium chloride or calcium
chloride may be included in de-icing mixtures. Their purpose
is to impart various properties to the de-icing mixtures mak-
ing them more effective. The nature and properties of these
additives are characterized in Table 1.

All or some of these additives may be found in a de-icing
mixture depending on the agency applying the mixture. In Wis-
consin, for example, only 10% of the de-icing salt mixtures
used contain sand. From 1/2 to 2/3 of the salt mixtures con-
tain sodium ferrocyanide. A chromium base rust inhibitor was

applied in de-icing mixtures in the 1955-56 winter in Michigan

but its use was discontinued after that season (80).

 

mx\ms new
manage“ an as:

nousnuaafl
GOHMOHHOO UGM Umfih

mumfiouco Esflpom
usmwpmumsfl m>fluom

A.osH Haflmumov mundmumo

 

mx\ms and
mpflnnsu as oqzlm wH
mo osHs> o>wufluu5s

nosnnnncn
COHmOHHOU UGM HmSH

mumsmmoam
Imumamxmn Eswpom
usmfiomumcw m>auom

A.OGH comamuv xosmm

 

n.3mwm on Oaxou memonum
no mmxma ca Baum
Ilunmwaczm ca ooficmwo
somonown mommoamn

“Hmnummou mCHxOHum Eoum
mamumhuo pawn musm>onmv
poems msflxmolflusm

amass.sizovmm.mz

Ameom
mo wumwmmsum soaamwv
moflsmmoounmm Endpom

 

cowHMOAMHofiom coma mo
mmmmamu no: mooollo a

sa mandaomswlls3ocx
In: moauummoum owxou

menme m mm pom:

mleizueomlemm

Amsam sawmmsnmv
mcwsmmoouumm oeuumm

 

oaxoulsoz
mowuuwmoum

 

m>wmmnn< as we com:
mmomusm

 

mamumaflz msowum>
rmEou Hmoflfimno

 

msmw
m>suwee¢

 

 

Amm.omv mm>fluwwo< uamw mcflofllma

.H wHQMB

There are other minerals available that can act as de-
icers but are not used extensively on highways. D-110[64],
used primarily on airport runways, contains 22-29% urea,
71-78% ammonium nitrate, and 2% sodium phosphate. A second
runway formulation contains 75% tripotassium phosphate and
25% formamide (80).

De-icers sold primarily for home use include ammonium
sulfate, ammonium nitrate, and a combination of potassium
pyrophosphate plus formamide. Many of these home de—icing
products have been shown by the Portland Cement Association to
damage concrete. De-icers,.such as these, which contain large
amounts of nitrogen or phosphorus may be undesirable used on
a large scale because of possible polluting effects on lakes

and streams (80).

Howdoes salt work?

 

It is generally understood that salt applied to highways
causes ice and snow to melt. The physical and chemical proc-
esses and the factors affecting these processes are not as
widely known. Coulter (28) has explained these processes.

When salt is applied for the control of ice or snow,
melting occurs because the vapor pressure of the liquid
phase of the water present is reduced. Water molecules
are emitted from the surface of both the solid and liquid
phases. At equilibrium, the emission of molecules from
the surface and condensation of molecules on a surface
are at the same rate. When both ice and water are present,
in time, all will pass into that phase having the lowest
vapor pressure (water) since condensation of vapor will
be more rapid on that phase than emission from it. The

excess of molecules for this condensation will be ob-

tained from the phase with the higher vapor pressure

(ice or snow).

In order for melting to occur the latent heat of
fusion (143.6 BTU's per pound of ice) must be supplied.

On a pavement the necessary heat is abstracted from the

ice adjacent to the melting area, from the atmosphere,

and from the pavement....' The rate of flow of heat is
directly proportional to the temperature differences
between the points of supply (the adjacent ice, the
atmOSphere, or the pavement) and demand (the melting
solution).

The type of salt applied to a highway can affect the rate
and effectiveness of the melting process. If ambient tempera—
tures are seldom less than 20°F sodium chloride is used. At
a temperature of 20°F, the eutectic temperature of NaCl (-6°F)
will permit a temperature differential of 26°F between the
melting solution and the surrounding environment thus melting
will occur at an acceptable rate. At ambient temperatures of
-7°F no melting will occur (28).

When temperatures fall below 10°F calcium chloride is
often used alone or with an abrasive. Because of its lower

eutectic temperature, CaCl can induce melting at very low

2
ambient temperatures. At temperatures of 10 to 20°F mixtures
of NaCl and CaClz are often used. CaCl2 has an affinity for
moisture and a positive heat of solution. When it is applied
to ice melting begins more rapidly but NaCl, which has a
greater driving force for melting, will melt more ice in a
given time period. CaC12, because of its deliquescent proper-

ties, captures moisture from the atmosphere and brings it into

contact with NaCl thus facilitating the melting process (80).

Miller (62) found a mixture of 1 part CaCl to 2 parts NaCl

2
by volume to melt ice and snow at a lower temperature than
NaCl alone, and to melt ice and snow faster at all tempera-
tures.

Grain size also affects the rate of melting. Small-sized
grains will increase the rate of melting; however, the salt
particle must penetrate into the ice or snow. If salt of a
very fine grain size is used,.1itt1e penetration will occur
and a film of brine may develop on top of the ice or snow mass.
This film produces a lubricating effect causing a loss in tire
traction. Larger size grains are able to penetrate to the
bottom of an ice or snow mass and along with lateral diffusion
of the brine permit traffic action to break up the ice sheet,
or, in the case of snow, produce a slushy condition which will
aid in snow removal (28).

A third factor in the melting process is the amount of
traffic in the salted area. Traffic movement assists in the
removal of ice and snow by the application of pressure to the
melting area, thus slightly lowering the melting point of the
ice or snow. The heat of tire friction and the casting of
loose snow or ice from the pavement by vehicular movement also
aid the melting process. If the temperatures of the environ-
ment and the melting solution are at equilibrium, traffic move-
ment will increase the rate of heat transfer to the melting

solution (28).

Ambient temperatures can affect the rate of snow and ice
removal by chemicals. Low air temperatures prior to salting
will slow removal, whereas high temperatures prior to salting
will hasten removal by causing heat to be stored in the pave-
ment. Removal will be slow if the atmospheric humidity is low
or if conditions for heat transfer are poor; wind or radiation
to a clear night sky causing poor heat transfer conditions (28).

Snow density and/or water content is also a factor in
ice and snow removal. Less heat is required to melt wet snow
than dry snow. Snow density and water content are affected by
temperature. Low temperatures and humidity favor dry, powdery
snow, while higher temperatures and humidity favor wet, dense
snow. Wind action can increase snow density by packing the
snow (28).

The rate of application of the salt mixture is one of the
most important factors affecting the melting process. A maxi-
mum rate of melting would be achieved if sufficient salt was
applied to make a eutectic solution in the water-equivalent of
the ice or snow that is being melted. In practice less than
that amount is applied. Providing some traffic is present,
removal of ice and snow is satisfactory if 40% of the weight
of the salt necessary to reduce the freezing point of the
equivalent water to the existing ambient temperature is
applied. The rate of application is influenced by the factors
previously discussed of salt type, grain size, traffic move-

ment, temperature, and snow density and/or water content (28).

10

Salts in the Highway Environment
Salts in the Water Supply

De-icing salts applied to highways may enter three
regions of the environment. They may splash or drift onto
plant foliage, they may splash onto or run off into the soil
bordering the highway, or they may be carried off in the
water supply to lakes, wells, streams, and ponds.

Schraufnagel (79) reported that in some areas of
Wisconsin winter roadside runoff contained up to 10,250 mg/l
chloride. Surface water in the area contained 45 mg/l
chloride. The summer roadside runoff contained only 16 mg/l.
Hutchinson (48) found the Na+ and Cl- content of water samples
taken daily during March and April from a culvert near an
interstate highway in Maine to range from 70.4 to 264.9 ppm
and 38.1 to 844.9 ppm respectively. Most ground-water samples
taken from highways in Massachusetts showed a chloride con-
tent of almost 250 ppm which is the upper limit recommended
by the United States Public Health Service for public water
supplies (83). Deutsch (31) reported alleged contamination by
salt storage of the Black River limestone at the Village of
the Rocks in Michigan.

Pollution of several roadside wells has been reported
by the Manistee County (Michigan) Sanitation Commission. In
1960 five wells in Wisconsin were reported to be affected by

salts leaching from a sand-salt stockpile (79).

11

Increased chloride concentrations in lakes, ponds, and
rivers as a result of de-icing salt runoff have also been
reported (1,9,48). Bubeck 25‘31. (17) reported that de-icing
salts have increased the Cl- concentration of Irondequoit Bay
fivefold in the past 20 years. In 1969 and 1970 the c1" con-
centration was sufficient to prevent the complete vertical
mixing of the bay in the spring and to delay the period of
summer stratification by one month. Blaser 92 31. (9) doubted

that de-icing salts are contaminating major waterways.

Salts in the Soil

 

Excess salts in the soil bordering salted highways and
resultant vegetation damage have been reported by several
observers (3,9,24,25,44,45,46,47,48,49,55,67,69,9l,94,95,101).
Holmes gt’gl. (47), while noting that direct application of
NaCl to the soil around trees can cause damage, doubted that
injury to deciduous trees occurred when salts were applied
to roads in moderate amounts during the winter only, however,
they did observe that trees in low areas may be damaged.

They hypothesized that any salt accumulated in the foliage of
trees along the highway would be removed when the leaves
abscised.

Holmes (45) in later work reaffirmed his findings. He
contended that the salt dissolved in the melted snow and ran

off over the frozen ground without reaching tree roots.

12

Holmes found that a small amount of salt did enter the top
layers of the soil causing damage to the grass under the
trees, but he felt that most of this salt was probably leached
out of the sandy loam soil before the foliage on the trees
expanded and before there was much water uptake by tree roots.

La Cease and Rich (55) found an inverse relationship be-
tween distance from the highway and salt injury symptoms.

The soluble salts in the tOp three inches of the soil border—
ing salted highways decreased significantly with distance from
the road. Most injury occurred within 30 to 100 feet of the
highway. Soluble soil salts were greater on the lower side

of the highway and injury to trees was greater on those trees
below the road level or in areas receiving drainage from the
highway.

Hutchinson and Olson (49) measured sodium and chloride
levels in soils adjacent to highways salted for periods rang-
ing from 0 to 18 years. Levels of both ions were found to
increase; Na+ levels increasing more than Cl- levels. Injury
was greatest at the edge of the highway and where salting was
practiced the longest. Salting increased Na+ and Cl— levels
more at a depth of 6 inches than at 18 inches. Increased
sodium and chloride levels were found at distances up to 30 to
35 feet and as far as 60 feet from the highway. Baker (3)
also found high sodium and chloride levels in soils bordering

salted highways.

13

Prior and Berthouex (67) noted that water can infiltrate
frozen forest soils to a depth of 4 inches; less infiltration
occurring in heavy soils. If the soil froze slowly permeabil—
ity was decreased. They found high concentrations of salt at
the soil surface and nearest the highway. ‘Salt concentrations
decreased with depth. Lateral movement of salt in the soil
was as great as 100 feet; however, after February, lateral
movement was only 25 feet. By April the salts had been
leached from the soil.

Westing (95) noted significant infiltration of salt solu-
tions into the soil even when the ground was frozen. In well-
drained, sandy soils the salts did not persist beyond March,
but in less well-drained soil types, the salts persisted
through summer and fall. Na+ and Cl- concentrations increased
slowly throughout the year. Westing found the direction and
rate of salt movement to be influenced by: 1) whether the
soil is frozen, 2) the amount and pattern of rainfall, 3) the
depth of the water table, and 4) the texture, structure,
chemistry, organic matter content, permeability, cation ex-
change capacity, and biota of the soil.

Zelazny and Blaser (101) found high concentrations of
Na+ and C1- to a depth of 18 inches throughout the winter in
soils bordering salted highways. Maximum concentrations of
salt were found at the soil surface and closest to the pave-

ment. The salt moved downward in the winter. Concentrations

14

increased from year to year. Higher than normal concentra-
tions of salt were found in the soil to a distance of 75 feet
from the highway.

Button and Peaslee (24) found that most plants more than
30 feet from the highway usually escaped injury, but some
plants as far as 100 feet from the highway were injured. Rich
(69) observed that trees within 30 feet of the highway were
affected by salt most frequently and severely. Blaser 35 31.
(9) also found injury to occur up to 30 feet from the highway;
injury being greatest at the edge of the highway. The dis-
tance at which injury occurred increased on curves. Hofstra
and Hall (44) found injury to trees up to 120 meters from the
highway.

Wester and Cohen (94) found a correlation between the
amount of salted snow piled within the root zone of trees and
the degree of injury to the trees. The amount of precipita-
tion in the spring was a critical factor in the severity of
the damage; no damage occurring when enough rain fell in the
spring to saturate the soil and provide for leaching of salts
from the soil. Holmes and Baker (46) observed that the factors
affecting the amount of injury to trees were: 1) the amount
of salt applied, 2) the timing of the application, 3) the
quality and drainage of the soil, 4) the dates of salting,

5) the depth and duration of soil freezing, 6) the depth of
snow piles, and 7) the amount of runoff before the ground

thaws.

15

Walton (91) noted that the higher the rate of applica-
tion of salt the earlier the symptoms appear on Norway maple
trees. The degree of phytotoxicity was found to be governed
by: l) the amount of rainfall during the growing season,

2) the amount of snow cover, and 3) the amount of rainfall in
the spring. Walton found a late spring salting to be more
phytotoxic than a winter salting. He hypothesized that when
salt washes to the roadside it may thaw the soil around the
plant to some degree forming a "sink". As a result, the plant
roots may be bathed in solutions of high salt concentrations

and osmotic pressures causing root injury.

Salts as Spray

De-icing salt spray churned up by moving traffic and de-
posited on the foliage has been reported to cause injury to
roadside plants (29,45,59,75,78,84). Wells and Shunk (93)
noted the importance of ocean salt spray as a factor in
coastal ecology. They observed injury to plants from salt
spray and were able to induce similar injury in test plants
with a 3% spray of NaCl. Oosting (65) also noted the effects
of salt spray on coastal vegetation as did Boyce (11). Death
of and injury to pine, spruce, privet, and dogwood were ob-
served along the New Jersey coast (77). Edwards and Holmes
(33) determined salt deposited by marine winds onto trees of

North Wales forests to be responsible for the observed injury

16

to those trees. Buccianti (18) described serious damage to
vegetation along the Mediterranean Coast from salt deposition
by strong sea winds.

Holmes (45) noted some injury to trees by NaCl and CaCl2
applied directly to the foliage. Sauer (78) observed that
de-icing salts had their greatest effect on the above-ground
portions of the plant. He noted that those portions of the
plant protected by snow cover escaped damage, the foliage of
taller plants which extended above the spray zone appeared
healthy, damage occurred only on the side of the plant facing
the highway, and those plants afforded some protection from
salt spray appeared healthy. Damage was greater in median
strips and on expressways where larger amounts of salt were
used and where increased traffic density and higher speeds
caused more spray and a wider spray. The type of vehicle was
found to affect the extent of the injury zone; trucks causing
injury higher up on trees because of their poor aerodynamic
design. Factors affecting the severity of injury were:

1) the amount of NaCl applied, 2) the time of first applica-
tion, 3) the distribution rate of total salts, 4) the time of
last application, and 5) climate; the most important in de-
termining injury being the amount of NaCl applied.

Salt spray damage to vegetation along New Jersey road-
sides was observed (75). Symptoms of injury were noticeable

within 30 feet of the highway; being more severe on plants

17

below the road elevation. Davidson (29) noted damage to
various species of pines along Michigan highways. Those
plants damaged most were located nearest the highway in the
salt splash or drift zone.

Smith (84) observed salt contamination of white pine
adjacent to an interstate highway. Foliar Na+ cancentrations
were greater than 1% on the highway side of the plants. The
threshold level of Na+ for injury was 0.5%. No abnormal Ca++
levels were found. Needles of south-facing trees contained
more Na+ than those of north-facing trees; the higher levels
in south-facing trees being attributed to the prevailing wind
patterns. Damage to white pine occurred up to 35 meters from
the highway.

Lumis, Hofstra, and Hall (59) found tree injury to de-
crease with distance from the highway. Injury was most severe
on the side facing the road. Plants on the downwind side were
damaged more severely. As traffic volume increased, plant
injury increased.

De-icing salts have been shown to run off into water sup-
plies, to splash onto or runoff into soils bordering highways,
and to be deposited on the foliage of plants bordering high-
ways. Damage from salts has been reported in all of these

regions of the environment. The fate of salts in the environ-

ment is depicted in Figure l.

18

.usmficoufl>cm mmsnmfin map CH muamm mo mush .H musmfim
wo<¢Ohm

.
5:; 06393 . 238 .225. 69.3
. .335... .828 .33.!
32:62:05 339.3 mm»;
_ -8

.++oo.+ez.
0252.0 4.0w

 

  
      

 

 

         

 

   
 

I)
/\ 02:..52
Ste F / / \\
mwmwn: .. :3: e] // / / 5.13.4.1
. Cifi\ 11.833! 8] // .\\
Prozac a 302m \

w>..0wm.o

0..

   

.5on .9153

o.

\

Imdqam

.... \\
'0
\....£o:<o3mz<EOmx<E: 5:5

«‘30...
3%. memmuwm\\
.3344“. .13.. 2on 20:26.25
. \ zofietaauze oz.)
co beenneu

ZOZAEEFmawm
oEwIQm02h<

 

   

 

0.2055

19

Effects of Salt on Plants
'Soil Salts

Chlorine and calcium are essential elements for plant
growth. Chlorine has been shown to be involved in the stimu-
lation of certain enzymes, in carbohydrate metabolism, in
chlorophyll production, and in the water-holding capacity of
plants (81). Bové 35 El: (10) found C1- to be required in
oxygen evolution by photosystem II of photosynthesis. Freney
22 31. (40) observed a build-up of free amino acids in chlorine
deficient plants and hypothesized that chlorine may be related
to amino acid synthesis or interconversion.

Calcium has been shown to be involved in the transloca-
tion of carbohydrates, in the develOpment of roots, and in the
integrity of cell walls (81). Ito and Fujiwara (51) and
Rasmussen (68) found calcium to have an important bearing on
the mechanical strength of plant tissues. Marinos (60) noted
the role of calcium in the maintenance of the structure of
membranes. Calcium-deficient barley shoot apex cells exhibited
structureless areas. Marshner gt_31. (61) found similar
results in calcium-deficient cells of barley and corn root tips.
Brewbaker and Kwack (12) found calcium to be indespensable for
the germination of pollen and the growth of pollen tubes in
plants from several families. Rios and Pearson (72) observed
that roots failed to grow in calcium-free soils.

Sodium is not generally required by green plants. Sodium

has been shown to be essential for satisfactory growth and

20

maximum yields of some plants including celery, sugar beets,
swiss chard, beets, and turnips (81). Certain species,
especially halophytes, require sodium. Brownell and Wood

(16) and Brownell (14) showed that Atriplex vesicaria requires
sodium as a micronutrient element. Brownell (15) observed
that several other species of Atriplex also have a sodium
requirement. Williams (96) found that Halogeton glomeratus
has such a high salt requirement that sodium may be considered
a macronutrient element for its successful growth.

Nieman (64) noted that sodium chloride stimulated growth
in tolerant crop plant species and increased the succulence
of the leaves of all species except onion. NaCl also in-
creased the ratio of water to dry matter in the leaves; the
greatest increase occurring in the most tolerant species.
Roberts and Zybura (73) observed that 600 ppm of NaCl applied
to the soil stimulated growth of several grass Species.

If chlorine, calcium, sodium, or combinations of these
ions are present in the soil solution or in plant tissues in
excessive amounts they can cause damage to plants. Excess
Salts in the soil solution can affect the plant in several
ways. The increased concentrations of salt in soil solutions
can increase the osmotic pressure of those solutions and thus
restrict the uptake of water by plant roots (7). Bernstein
gt_§l. (8) noted that water stress and salt damage can induce

similar leaf injury in a given species. Westing (95) noted

21

that salt damage was more severe in periods of extended drought
because salts in the soil make water less available. Salts and
drought reinforce each other; drought conditions resulting in
less leaching of salts and the movement of water upward from
lower soil layers thus concentrating the salts near the soil
surface. Prior and Berthouex (67) found salts to be more harm-
ful when soil moisture was at the wilting percentage. Zelazny
and Blaser (101) measured osmotic pressures of 1.5 atmospheres
in soils bordering a salted Vermont highway. Others have also
hypothesized that the mechanism of salt injury is a ”physio-
logical drought" caused by the interference by salt with normal
osmosis (76).

Salts in the soil solution may also be absorbed by plant
roots in the form of their constituent ions, Na+, Ca++, and
Cl—. These ions may then be translocated to other plant organs
such as leaves, stems, and buds and may accumulate in these
organs in toxic amounts (7).

Soil salts are taken up by the roots in.a largely active
and partially selective process. A certain amount of salt is
taken up passively by water movement into the roots. Once in
the root the salt ions face several obstacles to translocation.
The epidermis can be a partial barrier to some ions such as
calcium. A second barrier may be the protoplasmic membranes
of the cortical cells where passage of ions involves a

"carrier" system and is metabolically controlled. A third

22

barrier may be the xylem endodermis. When soil salt concen—
trations become very high these barriers become ineffective in
stopping the flow of salts into the plant (95).

Brown 22.51. (13) concluded from a study using six
varieties of stone fruit trees that the response to salinity
was influenced more by Specific ions than by the osmotic pres-
sure of the solution. Button and Peaslee (24) reached a
similar conclusion in work with sugar maples. Kotheimer gt_gl.
(53) found the chloride level of sugar maple leaves to be
correlated with salt damage. Button (23) also observed this
correlation in sugar maples. Chlorides accumulated in the
leaves and twigs to lethal or near lethal levels; the greatest
accumulation being in leaves and twigs of trees located in
areas of runoff. Kotheimer (52) found the levels of C1. in
foliage of damaged trees to be significantly higher than
levels in healthy trees. Hofstra and Hall (44) found injury
levels to be related to chloride levels in white pine and
white cedar needles. Chloride levels in the needles in excess
of 1% caused death. At similar levels of injury all pines
contained similar levels of Na+ and Cl-. Holmes 2; El: (47)
found no injury to trees on winter plots but did note higher
Cl- levels in leaves and twigs; leaf levels being highest.
Wester and Cohen (94) noted that Cl- levels in the leaves of
damaged trees were three times that of normal tissue. Davison

. + - .
(30) observed high Na and Cl levels in the foliage and seeds

23

of several roadside grasses. Shortle and Rich (82) reported
that uninjured roadside trees had higher Cl" contents in the
leaves than healthy trees in non-highway locations.

Baker (3) observed that while Na levels in the leaf were
abnormally high, leaf scorch symptoms were not associated
with Na+ levels. Levels of 1%(flf'in the leaves were respons-
ible for leaf scorch. Zelazny and Blaser (101) found the
greatest Cl- increase in leaves and the greatest Na+ increase
in the stem.

Verghese §E_§l, (89) found a close relationship between
application rates of salt and the amounts of Na+ and C1-
absorbed by grasses. Ehlig and Bernstein (34) observed that
the salt concentration influenced the rate of foliar accumula-
tion of salts but did not affect the level at which injury
occurred. The effects of Na+ and Cl- did not appear to be
additive since injury occurred at the same leaf content of
Na+ or Cl- alone as when both were present. Chloride accumu-

lated equally from NaCl and CaCl Kotheimer gt El' (53)

2.
indicated that CaClz-NaCl mixtures may be less harmful than
NaCl alone. Brown gt 31. (13) noted that CaCl2 was more toxic

than NaCl because Ca++ facilitates the entry of C1-. Strong
(87) noted that white pine was injured by lower soil concen-
trations of NaCl than CaClz.

An excess of one particular ion may influence the absorp-

tion of other ions essential for plant growth (7). This

phenomenon may be especially significant in soils found along

24

highways which are often low in fertility (89). Parups 23 a1.
(66) observed that increased amounts of C1- depressed the
absorption of K+. Kotheimer (52) reported greater C1- uptake
when higher levels of K+ were present in the soil. Leggett
(58) contended that K+ uptake and Cl- uptake were associated.
Walton (91) reported similar rate—limiting steps for K+ and
C1- absorption.

Holmes (45) thought NaCl to be more damaging than CaCl2
due to the ion antagonism between Na+ and K+. Button and
Peaslee (24) observed an antagonism between Na+ and K+ or Ca++7
however, Baker (3) found that Ca++, Mg++, and K+ levels in
leaf tissue were not affected by Na+ levels. Davison (30)
observed that K+ concentrations in grass clippings decreased
in relation to increases in the concentration of Na+. The
alteration of the K+/Na+ balance affected competition between
these grasses and other flora. Verghese 33 El: (89) noted
that increased rates of K+ decreased the uptake of Na+ by
certain grasses.

Sulphate, phosphate, and nitrate ions applied as sodium
salts decreased Cl- uptake.but not Na+ uptake. Phosphate ions
were most effective; an inverse relationship occurring between
phosphate and Cl- ion contents. Ca++ and K+ salts also de-
creased Na+ and C17 uptake; K+ salts being more effective (89).
Button and Peaslee (24) observed an antagonism between C1- and
certain organic acids. Hayward and Bernstein (43) prOposed

that NaCl and CaCl may inhibit nitrogen uptake.

2

25

Lastly, an excess of sodium ions in the soil may have a
detrimental effect on soil structure (71). Westing (95)
reports that if sodium reaches 15% of the cation exchange
capacity the soil structure deteriorates. The sodium ions
cause the clay particles of the soil to disperse thus decreas-
ing the permeability and water-holding capacity of the soil.
Roberts and Zybura (73) reported that 24,000 lb of NaCl
applied per mile of four lane highway in two successive
winters affected median and foreslope soil structure and pre-
vented satisfactory establishment of a grass cover.

Carpenter (25) noted that excess salts caused stunting
of all plant parts and reduced yield and quality. Bernstein
22.31. (8) hyPOthesized that NaCl interferes with normal
stomatal closure under high evaporative conditions causing
excess water loss. Strong (87) noted that CaCl2 killed cell
protoplasm by plasmolysis. Carter and Myers (26) indicated
that NaCl and CaCl2 added to irrigation water significantly
increased light reflectance from the upper leaf surfaces of
grapefruit. NaCl and CaCl2 also decreased chlorophyll con-
tents of the leaves. Metabolic activity was reduced. Carter
and Myers hypothesized that leaf structural changes may be
involved in plant responses to excess salts.

Damage from excess soil salts expresses itself as stunted

growth, marginal leaf scorch, foliage thinning, and preseasonal

defoliation. Sodium toxicity symptoms are: l) deeper green

26

leaves at first, 2) margin or tip burn with a sharp line
between burned and unburned areas, 3) bronze coloration of'
the leaves after burning, and 4) premature leaf drop.
Chloride toxicity symptoms are: 1) margin or tip burn of the
leaves, and 2) shoot tip dieback (81).

Bernstein and Hayward (7) observed that seasonal effects
may modify salinity expression. Holmes (45) noted less in-
jury at low temperatures. Prior and Berthouex (67) observed
less salt uptake at low temperatures. Bernstein (6) found
high temperatures to intensify leaf burn injury.

Holmes and Baker (46) noted that salt may affect the
susceptibility of trees to other injury and other agents may
affect the severity of salt injury. Symptoms from such
indirect effects as impaired aeration, water deficiency,
nutrient imbalance, and other biotic and abiotic agents may
be observed. Wester and Cohen (94) noted that salt damage

exposes the bark and branches of leaders to sun scald.

Salty§pray

Wells and Shunk (93) hypothesized that injury from salt
spray was due to excessive water loss from young tissues
resulting from the osmotic action of high salt concentrations
on unprotected surfaces. Boyce (11) noted that injury to
leaf cuticles by wind facilitated the entry of Cl- into leaves.
Subjecting leaves to wind prior to salt application resulted

in increased injury from salt and increased C17 ion

27

penetration. Cl- accumulated in young leaves in detrimental
amounts before older leaves were injured. Cl_ was concen—
trated at the tip of the leaf first. Regardless of where the
Cl- entered the leaf it was translocated to the tip. Cl- de-
posited on the windward side of the plant was not translocated
to the leeward side.

Bukovac and Wittwer (19) noted that foliar-applied Cl-
was readily absorbed. A high percentage of the chlorine was
transported to other plant parts, especially the stem. They
hypothesized that transport of C1- in the phloem may be the
limiting factor in its absorption and mobility.

Woolley 25 El. (98) observed that radio-chlorine applied
to the leaves of tomatoes and sugar beets reached all plant
parts in some quantity. More translocation of Cl- was ob-
served 8 days after application than one day after application.
Younger plant structures obtained radio-chlorine at the ex-
pense of older leaves. Retranslocation of Cl- from regions
of high Cl— concentration to regions of low Cl— concentration
was observed concurrent with a decrease in C1" concentration in
all plant parts.

Wittwer and Tuebner (97) also found C1. to be readily
absorbed by plant foliage. Patterns of Cl- absorption were
similar to those of P32. C1- uptake was found to be light
dependent. The action spectrum for C1" absorption was similar
to that for the chlorophyll system. Absorption of C1- of

Vallesneria was inhibited by cyanide, arsenate, and uranyl-

nitrate.

28

Laties (57) found the salt absorption process to be a
rapid initial uptake followed by a slower, more prolonged up-
take. The initial uptake is physical in nature while the more
prolonged uptake is dependent on respiration.

Franke (38) noted that halogen ions being small (10A)
were able to penetrate intermicellar spaces. Buschbom (20)
noted that after autumn leaf fall C1- ions penetrated through
the buds into the inner shoot tissues.

Symptoms of salt spray injury have been described by
several authors (ll,29,59,77,93). Wells and Shunk (93) noted
that the young growth of loblolly pine was killed by salt
spray. Symptoms appeared first on the tips of the leaves,
then on the leaves, and finally on the branches. There was a
lag in appearance of the symptoms from the time of applica-
tion. Boyce (11) noted that Cl- caused hypertrophy of meso-
phyll cells on the windward side of plants. Deciduous plants
exhibited a "sympodial" branching habit. Plants damaged by
salt along the New Jersey coast were found to be killed or
stag-headed. Dogwoods failed to bloom (77). Davidson (29)
noted that pines exhibited needle dessication on the highway
side only.

Lumis, Hofstra, and Hall (59) noted and described the
symptoms of de-icing salt spray injury in much detail on both
evergreen and deciduous species. Their findings were as

follows:

29

General injury patterns:
1 - injury more severe on side facing the road,

2

3
4
5

Symptoms

2

plants one-sided due to branch die-back

damage more pronounced on downwind side of
highway

plants further from road injured less

branches covered by snow not injured

injury to evergreens apparent in late winter,
injury to deciduous plants not evident until
spring

branches above the spray-drift zone not injured
or injured less

damage increased with volume and speed of
traffic and amount of salt applied to highway
plants damaged over several years lack vigor
and soon begin to die

less winter-hardy plants injured more severely
salt spray penetrates only a short distance into
dense plants

plants in sheltered locations lack injury
symptoms.

specific to evergreens:

needle browning moderate to extreme, beginning
at the tip

needle browning and twig dieback on the side
facing the road but none or very little on the
back side

no needle browning or dieback on branches near
the ground under continuous snow cover

needle browning and twig dieback less severe
further from the road

browning usually first evident in late February
or early March and becoming more extensive
throughout spring and summer.

specific to deciduous plants:

leaf buds on the terminal part of branches
facing the road very slow to open or do not open
new growth arises from the basal section of
branches facing the road, resulting in a tufted
appearance

flower buds on the side facing the road do not
open but flowering normal on back side.

30

Salt Tolerance, Avoidance,_and Alleviation of Injury

 

Soil Salts

Tolerance to salts may be measured in several ways:

1) the ability of a plant to survive on saline soils, 2) the
yield of a crop on saline soils, and 3) the yield of a crOp on
saline soils as compared to yield on non—saline soils (81).
Salt tolerance of ornamentals may be measured by the severity
of injury symptoms.

Holmes (45) observed that soil salt tolerance may be the
result of the tendency of the roots of salt tolerant plants
not to take up chlorine and/or the tolerance of plant tissues
to high levels of chlorine. The choice of rootstock influ—
enced the amount of chlorine accumulated by avocado trees.
Holmes further hypothesized that the depth of roots may be a
factor in escaping damage. Hayward and Bernstein (43) also
noted the significance of depth of rooting in escaping salt
damage as did Ruge and Stack (74).

Hofstra and Hall (44) thought it probable that more
resistant pines accumulate lower concentrations of salts.
LaCasse and Rich (55) noted that Na+ was more readily trans-
ported by maples than by other Species. Kotheimer (52) ob-
served that Norway maples tolerated higher levels of Cl- and
also naturally accumulated more Cl- than did sugar maples.
Rich and LaCasse (70) noted that white birch and white ash

+
failed to translocate Na to the leaves and were salt tolerant.

31

Shortle and Rich (82) found that red oak, white oak, red
cedar, and black cherry did not accumulate Cl-.

Epstein and Jeffries (37) noted that salt tolerance in-
volves aspects of tolerance and transport. Some species were
able to exclude ions from the intracellular centers of
metabolism. The possibility of true cytoplasmic tolerance to
a solute was also noted. Epstein and Jeffries indicated it
was possible to breed for salt tolerance. Baker (3) noted a
genetic difference in the ability of sugar maples to trans-
locate Na+ to Cl- ions.

Westing (95) theorized that early-age saline conditions
may adapt plants to higher soil salt levels at later ages.
Hanes £5 21' (41) noted that certain plant species increase in
tolerance to salt with growth and development. Redbuds (Cercis

Canadensis) were damaged less by salts when they were older

 

and/or growing rapidly.

Carpenter (25) observed that salt damage could be allevi-
ated by leaching salts from the soil, by washing the foliage,
or by applying gypsum. Verghese 25 El: (89) hypothesized

that the use of KH P0 with de-icing compounds may minimize

2 4
salt injury; however, Walton (91) found that the use of K SO

2 4
+ . .
to counter K deficiencies in early Spring increased salt
damage. K+ and Cl- were both absorbed.
E1 Damaty 2£.§$- (35) found that soybean plants and seed-

lings from wheat kernels soaked in CCC (2-chloroethyl tri-

methylammonium chloride) were more tolerant to salt. Amo-1618

32

(4-hydroxy-5 iSOprOpyl-Z methylphenyltrimethylammonium
chloride, l-piperidine carboxylate) and phosfon (2,4-dichloro-
benzyltributylphosphonium chloride) had the same effect on
soybeans. The CCC treated plants were healthier, more turgid,
and contained more chlorOphyll. The osmotic pressure of the
sap was higher for treated plants. Similar results were re-
ported in Utah (2). Bernstein and Hayward (7) noted that the
short/root ratio was an important factor in severity of salt
injury. Plants with excessive top growth exhibited severe
injury.

Hvass (50) recommended the use of CaNOB, urea, and
ammonium sulfate for road clearance. Blaser gt_al.(9) saw
the need for improved methods of storing, handling, and
applying salt. Salt should be considered during highway de-
sign; especially in the design of drainage systems. Design

of roadside plantings to minimize injury is also important.

Salt Spray

Oosting (65) noted that those plants with the toughest
leaves and heaviest cuticles were most resistant to salt
spray. Those plants with enrolled leaves had a smaller sur-
face for salt spray to adhere to. Rhizomes were a means of
survival for some plants. Seeds were little affected by salt
spray.

Boyce (11) studied the deposition of salt upon plant sur-

faces. The total concentration of salt deposited as spray

33

was influenced by the physical factors of impact deposition.
An increase in wind velocity increased the deposition effi-

ciency of droplets smaller than twenty microns, the deposi—

tion efficiency of droplets 5u_in size being 10%, while that
of lOu droplets being 95%. The efficiency of deposition was
greater on margins of a glass slide than in the center.

The size of salt spray droplets collected varied with the
size and position of the collecting surface (leaves or twigs);
the efficiency being greater on leaves of a smaller size.
Pines and small-needled plants accumulated more salt per unit
area because they are more efficient collectors of small drop-
lets. Salt was deposited uniformly on moving leaves. Smith
(84) noted a differential impaction of airborne material.
Those plants with a high surface/volume ratio exhibited more
injury.

Boyce (11) further observed that plants with a broad,
uniform canopy exhibited a low deposition of salt on leaves
just below the can0py level and on the upper leaves of the
canopy. Any young shoot or leaf which projected above the
canopy level was a very efficient collector and was killed by
high salt concentrations. Leeward and interior portions of
the plant received the lowest salt concentrations. Those
plants with a lower canopy angle had a higher salt spray
intensity. Wells and Shunk (93) noted that slightly depressed
shoots on certain plants escaped damage because of the suction

factor of the wind.

34

Buschbom (20) in studies on 240 deciduous and evergreen
species noted marked interSpecific differences in tolerance to
NaCl and CaClz. He noted that while the constitutional re-
sistance is of considerable significance in some Species, the
degree of resistance of the protoplasts is generally more
important and is often the deciding factor governing lethal
effects. In further work, Buschbom (21) noted that resistance
of the protOplasts in the stem tissue of broadleaved woody
species alters considerably during the course of the year.
Resistance is higher during winter dormancy than in summer
growth and is lowest during spring flush. Younger Shoots ap-
pear to be less resistant than older ones.

Lumis, Hofstra, and Hall (59) noted that increased amounts
of wax or bloom on spruce resulted in added protection from
salt spray; the bluer the spruce the more resistance to salt
spray. Deciduous trees or shrubs with resinous or submerged
buds were more resistant to spray. Resistant evergreens or
dense deciduous shrubs could be used as screens to trap spray.

Observations of salt spray damage along the New Jersey
coast indicated that feeding, watering, and mulching plants
helped in their recovery from injury. Rinsing plants with
water immediately after salt deposition decreased the amount
of injury (77). Bartlett (4) noted that Spraying the foliage
of plants with anti-dessicants effectively prevented injury
from salt spray. Sauer (78) observed that plants in good soil

exhibited less injury presumably because of their better

35

regeneration ability. Buccianti (18) found that an automatic
installation that wets the foliage when the wind reaches 40km
per hour aided in protection of plants along the Mediterranean
coast.

The salt tolerances of various woody and herbaceous plants
are listed in the appendix. These tolerances were compiled

from a review of the available literature on salt tolerance.

MATERIALS AND METHODS

Preliminary Survey

On January 28, 1972, a preliminary survey of highway tree

and shrub conditions was conducted in the Lansing—East Lansing

area.

Its purposes were 1) to determine the extent of de-

icing salt spray injury to trees and shrubs bordering the

highways in the Lansing-East Lansing area, 2) to become-

familiar with and observe de-icing salt Spray injury symptoms,

and 3) to search out areas for future, more intensive study.

The preliminary survey was conducted along the following

highways (Figure 2):

l)

2)

M-78 from the junction of M-78 and M-43 northeast to
the junction of M-78 and M—52. Plants along this high-
way are primarily evergreen species of varying matur-
ity; most trees being in a mature state. The plants
are located at distances from the highway of 10 to 100
feet. Plants are located below, at, or above the road
level; those at or below road level being predominant.
Traffic on the highway is heavy and travels at an
average speed of 65 miles per hour.

M-52 from the junction of M-52 and M-78 south to the
junction of M-52 and M-43. Plants along this highway

consist of mature red pine (Pinus resinosa) at a

36

37

/L

 

 

 

 

.muasaoa> mafimsmq umMMImsHmsmq 0:» SH muons mo>udm whencw uHmm

.255 or .

I).

—> 0031009 0:

 

{.— wmé

:o:(oo 2 .Al I

 

 

 

.m musmflm

 

 

 

oE

 

«who. can «so: 324 :33... 2:32... §

 

spgdoa puoig o: 4—

+24

3)

4)

5)

38

distance of approximately 30 feet from the edge of the
pavement. Plants are at road level. Traffic on the
highway is moderate; the average speed of the traffic
being 55 to 60 miles per hour.

M-43 from the junction of M-43 and M-52 northwest to
the junction of M—43 and M-78. Plants along this high-
way consist mainly of mature evergreen species at dis-
tances of 20 to 80 feet from the edge of the pavement.
Most plants are at road level. Traffic on this road
is heavy; travelling at speeds ranging from 25 to 50
miles per hour.

I-496 from the Trowbridge Road exit south to the junc-
tion of I-496 and I-96. Plantings along this highway
are approximately eight years old. Most plants are
above the level of the highway and are at distances of
10 to 60 feet from the highway. The plantings consist
of both evergreen and deciduous species. Traffic on
this highway is moderate to heavy and travels at an
average speed of 70 miles per hour.

I-96 from the easterly junction of I-96 and I—496 west
and north of the westerly junction of I-96 and I-496.
Plantings along this highway are approximately six
years old and consist of deciduous and evergreen
species. Most plants are at or slightly above road

level. Traffic is moderate on this highway and travels

39

at an average speed of 70 miles per hour. The plants
are at distances of 10 to 50 feet from the edge of
the pavement.

6) I-496 from the westerly junction of I—496 and I-96
east to the Trowbridge Road exit. Plantings in this
area are one to two years old and consist of deciduous
and evergreen species. The plants are above the road
level and are 20 to 40 feet from the edge of the pave-
ment. Traffic on this highway is heavy and travels
at an average speed of 70 miles per hour.

Plants bordering these highways were observed for any de-
icing salt spray injury symptoms. Symptoms of de-icing salt
spray injury as described by Lumis, Hofstra, and Hall (59) were
used to determine salt injury. Injury to various plant species

was recorded.

I-96 Survey

An additional survey of the plants bordering I-96 from
the easterly junction of I-96 and I-496 west and north of the
westerly junction of I-96 and I-496 was conducted in May of
1972 after the deciduous trees had begun to leaf out and the
current year's symptoms began to be expressed on evergreens.
‘Injury symptoms were observed and recorded on both evergreen
and deciduous species on the north and south sides of the high-

way. Plant injury was rated on a scale of 1 to 5 as follows:

40

l - no symptoms of salt injury

2 - minor symptoms of salt injury

3 - moderate symptoms of salt injury

4 - severe symptoms of salt injury

5 - very severe symptoms of salt injury or death of the

plant.

M-78 Survey

On March 21, 1973, a more detailed survey of salt injury
to plants bordering M-78 from the junction of M-78 and M-43
northeast to the junction of M-78 and.M-52 was made (Figure 2).
Symptoms of de-icing salt injury were observed and recorded on
both deciduous and evergreen plants. The plants were rated for
injury on a scale of 1 to 5 as previously discussed. In addi-
tion to the injury rating, the distance from the edge of the

pavement to the plant was estimated and recorded.

I-496 Survey

 

In April and May of 1972 and in late April of 1973 sur-
veys of tree and shrub conditions on I-496 from the Trowbridge
Road exit south to the junction of I-96 and I-496 were con-
ducted (Figure 2). Plants were observed for salt spray injury
symptoms, were rated for salt injury on a scale of l to 5, and
their distances from the edge of the highway were noted and

recorded.

41

Michigan ArboretumSurvsy

In April and May of 1972 and in late April of 1973 sur—
veys of tree and shrub conditions were conducted at the Ford
Motor Company's Michigan Arboretum in Dearborn, Michigan.
The arboretum is directly adjacent to the Southfield expressway
and consists of 95 Species of native Michigan shrubs and trees
(Figure 3). The plants are from 9 to 13 years old and are
located at distances of 40 to 100 yards from the expressway.
The arboretum is located on the east side of the expressway and
the prevailing winds are from the southwest.

Symptoms of salt spray injury were observed and recorded
for the various species. The distances from the highway of

each of the plant species were estimated and recorded.

Micrqprobe Analysis of Whine and Austrian
Pine Needle Surfaces 77

Needles of white (Pings strobus) and Austrian (Pings
nigns) pine were collected from trees growing along M-78 in
the salt spray zone and from trees growing on the Michigan
State University campus where no salt spray could reach the
needles. The needles were cut into one centimeter sections
beginning at the tip. These centimeter sections were then
mounted with television tube koat onto carbon discs taking care
to preserve the proper orientation (tip to base) of the needle

sections. The sections were then coated with carbon to a

thickness of 100 A.

42

 

 

 

 

 

 

 

 

 

 

 

 

 

.E:uouonu¢ cmmflnoflz m.msmmsoo Mono: Unomllmoum >0>H5m Sunnsfl uHmm .m enemas
Eammmmexm Y. z
ouw...:._._.30m
its 0.. QQOQ hogtmm
J W o. J J
EUROQo 9.5 $9 @Onmwnmmu A
a .. . o . inhefsea s.
0m G 0 w Aw 0v 9%
c O Q &

 

 

43

Horizontal line profiles for sodium and chlorine were
then made on the EMX-SM electron microprobe of the surface of
each section closest to the tip. A distance of 480 microns
was scanned on each section. Operating conditions for the
microprobe were 15 KV and 0.02 microamps of current. Magnifi-

cation was 500x.

Micr0prsbe Analysis of White and Austrian
Pine Needle Cross SectiOns ’7

Needles of white and Austrian pine were collected from
the highway and nonhighway sides of trees growing along M-78
in the salt spray zone and from trees growing on the Michigan
State University campus where no salt spray could reach the
needles. The needles were embedded in O.C.T. and sectioned on
a cryostat to a thickness of 8 micrometers. Randomly chosen
sections were mounted on carbon discs; O.C.T. being used as a
mounting material. The sections were then coated with carbon
to a thickness of 100 A.

Horizontal line profiles for sodium and chlorine were
made on the EMX-SM microprobe of randomly selected portions of
each section. The portions of the sections scanned were 200
micrometers in length. Operating conditions for the microprobe
were 15KV and 0.02 microamps of current. Magnification was

500x.

RESULTS AND DISCUSSION

Preliminary_Survey

De-icing salt spray injury was observed along highways
in the Lansing-East Lansing area. The symptoms of salt spray
injury on evergreens were observed to be Similar to those
described by Lumis, Hofstra, and Hall (59). Needle browning
was observed on the highway side of susceptible plants. On
the highway side of older plants bud necrosis, in addition to
needle browning, was observed. The needle browning began at
the tips of the needles and progressed toward the base.
Symptoms were evident on the highway side of the plant only.
Plant portions above or beyond the spray or drift zone
exhibited no injury symptoms. Symptoms were observed to be
less severe further from the road.

De-icing salt spray injury was observed on some species
in all areas surveyed. White pine (P_i_._r_1g_s strobus) was severely
injured. This species exhibited severe needle browning on
the highway side. Many white pines exhibited bud necrosis.
Several young white pines were dead. Norway spruce (Piggg
sniss) exhibited Slight needle browning as did Douglas fir
(Pseudotsuga taxifolia). Scotch pine (Pings sylvestris),

arborvitae (Thuja occidentalis), red pine (Pinus resinosa),

44

45

and juniper (Juniperus sen.) exhibited moderate salt spray
injury. Needle browning was evident on the highway side of
the plants but there was very little bud necrosis. Austrian
pine (3&22§.2ifl£2) and Colorado spruce (Pisss pungens)

exhibited no injury symptoms.

I-96 Survey

Soil conditions were very poor at this site. The soil
was very hard and extremely dry. Symptoms observed on ever-
greens were similar to those observed on evergreens in the
preliminary survey. Injury from saw fly was noted on Scotch
pine (Pings syiyestris). Symptoms of salt spray injury on
deciduous species were observed to be similar to those
described by Lumis, Hofstra, and Hall (59). Those branches
on the highway side of the plant exhibited tip necrosis; those
injured for more than one year exhibiting a "tufted" branching
habit (Figure 4). Flowering was severely reduced on the highway
side of the plant. Injury from tent worms was observed on
H2l2§.§2230 Crataegus grusgslli, and Crataeggs onyacantha.
Injury ratings for the various species observed are presented

in Table 2, on page 47.

M-78 Survey
Sumptoms of de-icing salt spray injury were observed on
plants located on both the north and south sides of M-78.

There was no apparent difference in the amount of plant injury

46

 

.Ammumoouoms msoumsov #60 man no monocmno ecu mo mafiumse

.v shaman

 

47

Table 2. Average salt Spray injury ratings of plants border—
ing I-96--May 1972. .

 

 

 

Species Average Injury Rating
Acer campestre 2.0
Acer ginnala 2.0
Acer platanoides 1.5
Acer rubrum 2.0
Acer saccharum 4.0
Crataegus crusgalli 2.5
Crataegus monogyna 2.5
Crataegus oxyacantha 3.5
Euonymus europaeus 4.0
Elaeagnus angustifolia 1.5
Fraxinus pensylvanica lanceolata 1.5
Gleditsia triacanthos 3.0
Malus floribunda 4.0
Pinus nigra 1.5
Pinus strobus 4.0
Pinus sylvestris 3.0
Platanus occidentalis 4.0
Populus deltoides 1.0
Quercus alba 1.5
Quercus palustris 2.5
Quercus robur 4.
Quercus rubra 4.0

Rhus typhina 1.0

 

48

between the north and south sides of the highway. Injury
expressed as needle browning and bud necrosis was observed on
both the highway and non-highway sides of white pine (Pings
strobus). Injury symptoms were observed to a vertical distance
of 30 feet with most injury occurring at a height of 20 feet
or below. American Beech (Psggs_grandifolia) located on the
north side of M-78 at a distance of 20 feet from the highway
exhibited slight "tufting" of the branches on the highway side
of the trees. White oak (Quercus sins) 18 feet from the high-
way exhibited moderate tufting on the highway side. Green ash
(Fraxinus pensylvanica lanceolata) and red maple (Assn_rubrum)
exhibited no injury symptoms at distances of 10 and 30 feet
from the highway. Shagbark hickory (EEEXE.EXEEE) exhibited no
injury symptoms at a distance of 15 feet from the highway.

Pin oaks (Quercus pslustris) located 20 feet from the highway

 

exhibited bud and tip necrosis on the highway side. Average
injury ratings of evergreens observed on M-78 are presented in

Table 3, on the following page.

I-496 Survey

 

Injury symptoms similar to those observed in other areas
on both deciduous and evergreen species were noted. Injury
occurred on some species at distances of 60 feet from the
highway. Average injury ratings of those Species observed are

presented in Table 4, on page 50.

49

Table 3. Average salt spray injury ratings of evergreens
observed on M-78--March 1973.

 

v— a

 

 

Species Average Injury Rating
Juniperus spp. 2.5
Picea abies 1.5
Picea glauca 1.5
Picea pungens 1.0
Pinus banksiana 4.0
Pinus nigra 1.0
Pinus resinosa 2.5
Pinus strobus 4.0
Pinus sylvestris 1.5
Pseudotsuga taxifolia 2.0

Taxus spp. 1.0

 

Table 4. Average salt spray injury ratings of plants
observed on I-496--April 1972 and April 1973.

 

 

Species

Average Injury Rating

 

Acer ginnala

Acer platanoides
Acer rubrum

Acer saccharinum
Acer saccharum
Cornus stolonifera
Crateagus crus-galli
Crataegus oxyacantha
Euonymus alatus
Gleditsia triacanthos
Ligustrum spp.

Malus spp.

Pinus nigra

Pinus strobus

Pinus sylvestris
Populus deltoides
Pseudotsuga taxifolia
Quercus coccinea
Quercus palustris
Rhamnus spp.
Rhodotypos scandens
Salix spp.

Spiraea vanhouttei
Thuja occidentalis
Ulmis pumila
Viburnum dentatum

1.0
3.5
2.5
2.0
1.0
3.0
1.0
3.5
1.0
3.0

 

51

Michigan Arboretum Survey
Injury to many deciduous and evergreen species was noted.
Injury was very severe on certain species. Many deciduous
trees exhibited severe "tufting" of the branches and many
evergreen species exhibited browning of the needles. Injury
occurred on trees as far as 250 feet from the highway.
Average injury ratings for the species observed are presented

in Table 5, on the following page.

cccccc

Microprobe snaiysiS'ofWhite and'Austrianu
‘Pine‘Needle'SurTaces

Representative relative X-ray intensities for sodium and
chlorine of white and Austrian pine needle surfaces from high-
way and non-highway trees indicate that there is a greater
amount of sodium and chlorine on the surface of both white and
Austrian pine needles from highway trees (Figures 5 and 6).
The X-ray graphs indicate further that the sodium and chlorine
on the surface of the Austrian pine needles from the highway
area is more evenly distributed along the needle than the
sodium and chlorine on the surface of the white pine needle
from the highway area. Most of the sodium and chlorine on the
white pine needle was concentrated on the upper (tip) one-

third of the needle.

Table 5. Average de-icing salt Spray injury ratings of
plants at the Michigan Arboretum--l972 and 1973.

 

Y‘

Species

Average Injury Rating

 

Acer saccharum

Acer saccharum nigrum
Acer rubrum

Aesculus glabra
Amelanchier canadensis
Cercis canadensis
Cornus racemosa
Hamamelis virginiana
Ilex verticillata
Larix laricina
Liriodendron tulipifera
Morus rubra

Nyssa sylvatica

Picea canadensis
Picea mariana

Pinus banksiana

Pinus nigra

Pinus resinosa

Pinus strobus
Platanus occidentalis
Prunus americana
Quercus alba

Quercus bicolor
Quercus coccinea
Quercus imbricaria
Quercus macrocarpa
Quercus palustris

Quercus prinus

3.0
3.5
4.5
4.0
3.5
1.5
4.0
3.5
4.0
Continued

Table 5—-Continued

___._—

Species

53

T

Average Injury Rating

 

Quercus rubra

Quercus velutina

Rhus glabra

Rhus typhina

Salix nigra

Sassafras variifolium
Viburnum americanum
Viburnum lentago

 

54

CAMPUS

SODIUM
--- - CHLORINE

 

J"\d"s- \‘

 
   

Ieletive IMenelty

 

 

HIGHWAY

>

’
:3

 

 

I
g
l
E
:
I

 

 

.-
"-
"

 

‘2

 

 

 

Relative Ieteeeny

 

______,77

(I

‘~‘

 

 

--------‘

   

k

 

 

 

 

 

 

 

[e 2.... .I

Figure 5. Representative relative X-ray intensities of
sodium and chlorine on white pine needle surfaces.
(Background equals 1.5 counts/sec. for C1" and
1.6 counts/sec. for Na+.) Vertical hash marks
indicate divisions between needle sections.

55

‘--

 

 

 

 

CAMPUS

SODIUM
---- CHLORINE

'- /\ “

 

 

 

 

 

 

 

 

 

 

2400 p
Dietence

 

 

 

 

3.2.2... .23....

sodium and chlorine on Austrian pine needle sur-

Representative relative X-ray intensities of

 

 

 

 

 

 

 

 

 

 

 

HIGHWAY
Figure 6.

3.2.2... 3:2...

Vertical hash

(Background equals 2.5 counts/sec. for
marks indicate divisions between needle sections.

Cl' and 1.9 counts/sec. for Na+.)

faces.

56

Microprobe Analysis of White and Austrian
Pine Needle Cross Sections "

Representative x-ray intensities for sodium and chlorine
of white and Austrian pine needle cross sections indicate
that the needle sections from the highway side of both Austrian
and white pine contain more sodium and chlorine than do sec-
tions of needles from the non-highway side of the same trees
or needles from the campus trees (Figures 7 and 8). There is
a slight increase in x-ray intensity of sodium and chlorine in
non-highway needle sections as compared to campus needle sec-
tions. When the intensities of the highway side sections of
Austrian pine are compared with those of white pine (Figures 7

and 8), at least as much sodium and chlorine is observed in

the Austrian pine sections as in the white pine sections.

57

CAMPUS
— SODIUM
.. _ ---- CHLORINE
'3
5 IO counte
E -
e
.2
E
. )—
K

 

 

 

NON-HIGHWAY

I

_

Relative Intensity
I

 

 

 

 

 

HIGHWAY n
I \ “ A
(- f ‘.I’I ' \ I‘\
I ‘f\ ./ ‘ ’ \
I ‘V ’ V‘ ' \
0,: I ‘u’ ‘ ’ | A
7. {A [I \,I . J
5 i ‘v i /
E - [I \J“
5 .. f f
e- I‘
o __ I ~’
‘6
K
It 200 ,. aI

 

 

Distance

Figure 7. Representative relative X-ray intensities of
sodium and chlorine in white pine needle cross
sections (Background equals 1.8 counts/sec. for
C1’ and 1.8 counts/sec. for Na+).

58

CAMPUS
I

SODIUM
---- CHLORINE

 

IO counts

Relative Intensity

 

 

 

NON-HIGHWAY

 

 

 

F
3‘
a; -
c
2
5
. -
.2
E
. b
C
HIGHWAY
. I‘
q
I’ ”I I ’\ "ti Hi "\
‘JI I I v \H I t
3: I- ‘ I II VI I \
3 , I t; | I t l‘
\
c 3‘ I I; ‘\./ t /
2 l (j ‘J I I
.5 I 5 ‘ I
I- A ’_’ -1

5 ’-’L/
3 O ’
3 b " \\”
I

 

 

 

 

I‘— 200 p ’l

Distance
Figure 8. Representative relative X-ray intensities of
sodium and chlorine in Austrian pine needle
cross sections. (Background equals 1.7 counts/sec.
for C1. and 1.3 counts/sec. for Na ).

SUMMARY AND CONCLUSIONS

Symptoms of salt spray injury were observed on both
deciduous and evergreen species growing along highways in the
Lansing-East Lansing area and at the Michigan Arboretum in
Dearborn, Michigan. Symptoms of salt spray injury on ever—
green species were observed to be 1) browning of the needles
from the tip to the base, 2) injury evident on the highway
side of the plant only, 3) plant portions above or beyond the
spray or drift zone were uninjured, and 4) symptoms were less
severe further from the road. Symptoms of salt spray injury
on deciduous species were observed to be 1) tufting of the
branches due to death of the apical bud, 2) lack of flowering
on the highway side of the plant, 3) plant portions above or
beyond the spray or drift zone were uninjured, 4) symptoms
were less severe further from the road.

Injury was observed on plants at distances as far as 250
feet from the highway and to a vertical distance of up to 20
feet. Wind seemed to be a factor in carrying the spray drift
to greater distances. Also the type of vehicle and speed of
the vehicle were observed to be factors in determining the
extent of the spray drift.

Average salt spray injury ratings and tolerances of all

plants observed along Michigan highways are listed in Table 6.

59

60

Table 6. Average salt spray injury ratings and tolerances of

plants bordering selected Michigan highways.

 

 

Botanical Name

Common.Name

Average
Injury
Rating Tolerance*

 

Acer campestre

Acer ginnala

Acer platanoides

Acer rubrum

Acer saccharinum

Acer saccharum

Acer saccharum nigrum
Aesculus glabra
Amelanchier canadensis
Cercis canadensis
Cornus racemosa

Cornus stolonifera
Crataegus crusgalli
Crataegus monogyna
Crataegus oxyacantha
Elaeagnus angustifolia
Euonymus alata
Euonymus europaeus

Fraxinus pensylvanica
lanceolata

Gleditsia triacanthos
Hamamelis virginiana
Ilex verticillata
Juniperus Spp.

Larix laricina

*

VT=very tolerant; T=tolerant, MT=moderately tolerant;

Hedge maple

Amur maple

Norway maple

Red maple

Silver maple
Sugar maple

Black maple

Ohio buckeye
Juneberry

Redbud

Gray dogwood
Redosier dogwood
Cockspur hawthorn
Singleseed hawthorn
English hawthorn
Russian olive
Winged euonymus
European euonymus
Green Ash

Common honeylocust
Common witch-hazel
Michigan holly
Juniper

Tamarack

S=sensitive, and VS=very sensitive.

2.0
3.0
2.0
2.5
2.0
3.5
3.0
1.0
2.0
4.0
2.5
3.0
2.0
2.5
3.5
1.5
1.0
4.0
1.5

T
MT
T
MT
T
S
MT
VT
T
S
MT
MT
T
MT
S.
T
VT
S
T

MT
MT
T
MT
T

Continued

Table

6--Continued

61

 

Botanical Name

Ligustrum spp.

Liriodendron tulipifera

Malus
Morus
Nyssa
Picea
Picea
Picea
Picea
Pinus
Pinus
Pinus
Pinus
Pinus

spp.
rubra
syvatica
abies
glauca
mariana
pungens
banksiana
nigra
resinosa
strobus
sylvestris

Platanus occidentalis

Populus deltoides

Prunus americana

Pseudotsuga taxifolia

Quercus

alba

Quercus bicolor

Quercus
Quercus
Quercus
Quercus
Quercus
Quercus

coccinea
imbricaria
palustris
prinus
robur
rubra

Quercus velutina

Common Name

Privet

Tulip tree
Crabapple

Red mulberry
Black gum
Norway spruce
White spruce
Black spruce
Colorado spruce
Jack pine
Austrian pine
Red pine
Eastern white pine
Scotch pine.
American sycamore
Cottonwood
American plum
Douglas fir
White oak

Swamp white oak
Scarlet oak
Shingle oak

Pin oak
Chestnut oak
English oak

Red oak

Yellow oak

Average
Injury

Rating Tolerance

3.0

h
o

:5 OJ :5 lb (.0 l-‘ w uh u N w l-' O) N :5 N H w H (.0 N H b) H th-
e
O U! 0 O 0 U1 U! 0 U1 0 U1 U1 0" O 0 L11 ()1 O 0 U1 01 UI O 01 0

MT
8
S
T
MT
T
MT

3 ha 3 <3 m
a as

rammmamramr-am

m a)!» z
a

S

Continued

Table 6--Continued

62

 

,—

 

Average

Injury
Botanical Name Common Name Rating Tolerance
Rhamnus spp. Buckthorn 2.0 T
Rhodotypos scandens Black jetbead 1.0 VT
Rhus glabra Smooth sumac 1.5 T
Rhus typhina Staghorn sumac 1.5 T
Salix spp. Willow 2.5 MT
Sassafras variifolium Silky sassafras 3.5 S
Spiraea vanhouttei Van houtte Spirea 1.0 VT
Taxus spp. Yew 1.0 VT
Thuja occidentalis American arborvitae 4.0 S
Ulmus pumila Siberian elm 1.0 VT
Viburnum americanum American cranberry 1.5 T

bush

Viburnum dentatum Arrow wood 3.0 MT
Viburnam lentago Nannyberry 2.5 MT

 

63

Tolerance ratings were based on average injury ratings.
Injury ratings were averaged over time, location, and distance
from the edge of the highway.

The plants observed to be most tolerant to salt spray
were those with heavy coatings of wax on the foliage, stems,
or buds (Pings nigns, Aesculus glabra, Pngs glabra, Fraxinus
pensylvanica lanceolata, and Pigss_pungens). Those plants
with pubescent coatings on the stems, buds, or foliage were
also observed to be very tolerant (Amelanchier canadensis,
Pngs typhina, and Elaeagnus angustifolia). .Other character-
istics observed to be factors in salt spray tolerance were
submerged buds (EEEEE laricina) and persistence of the foliage
(Quercus imbricaria).

Those plants that were observed to be sensitive to salt
spray had exposed buds without a thick waxy coating. Some of
these sensitive species were very fine textured and thus had
a high surface to volume ratio (Pings strobus).

Results of the microprobe analysis indicate that the
sodium and chlorine on the surface of the Austrian pine needles
was more evenly distributed than the sodium and chlorine on the
surface of the white pine needle. This may be due in part to
the coalescence of the white pine needles upon becoming wet.

Results of micrOprobe analySis of cross sections indicate
that the tolerance of Austrian pine is not due to its ability
to exclude sodium or chlorine from the interior of the needle.

The contents of sodium or chlorine in the Austrian pine needle

64

sections were just as great as those of the white pine needle
sections. Hofstra and Hall (44) found similar injury symptoms
at similar sodium and chlorine needle levels and hypothesized
that resistance was due to the fact that resistant Species
accumulated less salt. White pine exhibited severe injury
symptoms whereas Austrian pine exhibited no injury symptoms.

The tolerance of Austrian pine to de-icing salt spray
may stem from two sources: (a) the ability of Austrian pine
needle cells to tolerate high concentrations of sodium and
chlorine or (b) the ability of the Austrian pine needle to
restrict water loss resulting from the osmotic action of high
salt concentrations on the needle surface. Buschbom (20)
found the degree of resistance of the protoplasts to be more
important than constitutional resistance and thought it to be
the governing factor in lethal effects. In further work
Buschbom (20) noted interSpecific differences in the proto-
plasmic resistance of broadleaved woody species. This resist-
ance was lowest at spring flush when most salt injury symptoms
appear.

Several researchers have determined the cause of salt
spray injury to be an osmotic effect rather than a specific
ion effect (56, 87, 93). Oosting (65) observed that plants

with heavily cutinized leaves showed no salt injury symptoms.

LITERATURE CITED

10

11

12

LITERATURE CITED

Adams, Franklin 8. 1972. Highway Salt: Social and en-
vironmental concerns. Presented to Hwy Res. Board. 5th
Summer Meeting. Madison, Wisconsin.

Anonymous. 1961. Chemical growth retardants can increase
plant salt tolerance. Utah Ag. Expt. Sta. Farm and Home
Sci. 22:114.

Baker, J. H. 1965. Relationship between salt concentra-
tion in leaves and sap and the decline of sugar maples
along roadsides. Mass. Ag. Expt. Sta. Bull. No. 553.

16 pp.

Bartlett, R. A. 1962. Spraying trees and shrubs for
winter damage protection. Trees Mag., Ohio. 23:13.

Bernstein, L. 1958. Salt tolerance of grasses and for-
age legumes. U.S.D.A. Ag. Inf. Bull. No. 194. 7 pp.

Bernstein, L. 1964. Reducing salt injury to ornamental
shrubs in the West. USDA Home and Garden Bull. No. 95.

Bernstein, L., and H. E. Hayward. 1958. Physiology of
salt tolerance. Ann. Rev. Plant Physiol. 9:25—46.

Bernstein, L., L. E. Francis, and R. A. Clark. 1972.
Salt tolerance of ornamental shrubs and ground covers.
Journ. Amer. Soc. Hort. Sci. 97(4):550-556.

Blaser, R. E., R. E. Hanes, and L. W. Zelazny. 1968.
Effects of de—icing compounds on vegetation and water
supplies. Preliminary Report. VPI, Blacksburg, Va.

Bove, J. M., C. Bove, F. R. Whatley, and D. I. Arnon.
1963. Chloride requirement for oxygen evolution in photo-
synthesis. Z. Naturforsch 186:683-688.

Boyce, S. G. 1954. The salt spray community. Ecologi-'~
cal Monographs. 24:29-67.

Brewbaker, J. L., and B. H. Kwack. 1963. The essential

role of calcium ion in pollen germination and pollen tube
growth. Am. J. Bot. 50:859-865.

65

13

14

15

16

17

18

19

20

21

22

23

24

66

Brown, J. W., Wadleigh, and H. E. Hayward. 1953.
Foliar analysis of stone fruit and almond trees on
saline substrates. Proc. Amer. Soc. Hort. Sci. 61:
49‘55 e

Brownell, P. F. 1965. Sodium as an essential miconu—
trient element for a higher plant (Atriplex vesicaria).
Plant Physiol. 40:460-468.

Brownell, P. F.,and G. Wood. 1957. Sodium as an essen-
tial element for some higher plants. Plant and Soil.
28:161-164.

Brownell, P. F., and G. Wood. 1957. Sodium as an essen-
tial element for Atriplex vesicaria, Heward. Nature
179:635-636. -

Bubeck, R. C., W. H. Diment, B. L. Deck, A. L. Baldwin,
and S. D. Lipton. 1971. Runoff of de-icing salt:
Effect on Irondequoit Bay, Rochester, N. Y. Science.
172:1128-1131.

Buccinati, M. 1970. Trials of new methods Of protec-
tion against salt sea winds in Versailles. Monti e
Boschi. 21(2):25-33.

Bukovac, M. J., and S. H. Wittwer. 1957. Absorption
and mobility of foliar applied nutrients. Plant Physiol.
32:428-435.

Buschbom, U. 1968. Salt resistance of aerial shoots of
woody plants. I. Effects of chlorides on shoot surfaces.
Flora, Jena. 157B:527-561.

Buschbom, U. 1968. Salt resistance of aerial shoots of
woody plants. II. Effects of chlorides on tissues of
the axis-seasonal course of resistance. Flora, Jena.
158B:129-158.

Butler, J. D., T. D. Hughes, G. D. Sanks, and P. R. Craig.
1971. Salt causes problems along Illinois highways.
Illinois Research, Univ. Ill. Ag. Expt. Sta. 13:No. 4.

Button, E. F. 1965. Ice control, chlorides, and tree
damage. Public Works. 96(3):136.

Button, E. F., and D. E. Peaslee. 1967. Effect of rock
salt upon roadside sugar maples in Connecticut. Hwy.
Res. Rec. 161:121-131.

25

26

27

28

29

30

31

32

33

34

35

36

37

67

Carpenter, E. D. 1970. Salt tolerance of ornamental
plants. Amer. Nurseryman. Jan. 15, 1970. 131:12.

Carter, D. L., and V. I. Myers. 1963. Light reflectance
and chlorophyll and carotine contents of grapefruit
leaves as affected by Na SO , NaCl, and CaCl . Proc.
Amer. Soc. Hort. Sci. 82:217-221. 2

Cordukes, W. E. 1970. Tolerance to road salt. Golf
Supt. 38:5, 44.

Coulter, R. G. 1965. Understanding the action of salt.
Public WOrks. 96(9):78-80.

Davidson, H. 1970. Pine mortality along Michigan high-
ways. Hortscience 5(1):12-13.

Davison, A. W. 1971. The effects of de-icing salt on
roadside verges. I. Soil and plant analysis. J. Appl.
Ecol. 8:555-561.

Deutsch, M. 1963. Ground water contamination and legal
controls in Michigan. Water-Supply Paper 1691. U. S.
Geol. Surv. 79 pp.

. 1971. Development of ground covers for high-
way slopes. Univ. of Minn. Dept. Hort. Sci. Ag. Expt.
Sta. Tech. Bull. No. 282.

Edwards, R. S., and G. D. Holmes. 1968. Studies of air-
borne salt deposits in some N. Wales forests. Forestry
41:155-174.

Ehlig, C. F., and L. Bernstein. 1959. Foliar absorp-
tion of sodium and chloride as a factor in sprinkler
irrigation. Procl Amer. Soc. Hort. Sci. 74:661-670.

El Damaty, H., H. Huhn, and L. Linser. 1964. A prelimi-
nary investigation on increasing salt tolerance of plants
by application of (Z-chloroethy1)trimethyl ammonium
chloride. Agrochimdca 8:129-138.

. 1960. Elm and maple in St. Paul--Salt injury
to trees. Nat. Arborests Assn. Newsletter. Val. 177
(May).

Epstein, E., and R. L. Jeffries. 1964. Genetic basis
of selective ion transport in plants. Ann. Rev. Plant
Physiol. 15:169-184.

38

39

40

41

42

43

44

45

46

47

48

49

50

68

Franke, W. 1967. Mechanisms of foliar penetration of
solutions. Ann. Rev. Plant Physiol. 18:281-300.

French, D. W. 1959. Boulevard trees damaged by salt
applied to streets. Minn. Home and Farm Sci. 16:9,22,23.

Freney, J. R., C. C. Delwiche, and C. M. Johnson. 1959.
The effect of chloride on the free amino acids of cabbage
and cauliflower plants. Austral. J. Biol. Sci. 12:160-
161.

Hanes, R. E., L. W. Zelazny, and R. E. Blaser. 1970.
Salt tolerance of trees and shrubs to de—icing salts.
Hwy. Res. Rec. Wash. No. 335:16-18.

Hansen, W. F. 1966. Salt damage, winter 1965-66.
Gartner Tidende 82:491-492.

Hayward, H. E., and L. Bernstein. 1958. Plant-growth
relationships on salt-affected soils. Bot. Rev. 24:584-
635.

Hofstra, G., and R. Hall. 1971. Injury on roadside
trees: Leaf injury on pine and white cedar in relation
to foliar levels of sodium and chloride. Can. Journ.
Bot. 49:613-622.

Holmes, F. W. 1961. Salt injury to trees. Phyto-
pathology 54:712-718.

Holmes, F. W., and J. H. Baker. 1966. Salt injury to
trees II. Sodium and chloride in roadside sugar maples
in Massachusetts. Phytopathology. 56:633-636.

Holmes, F. W., J. S. Demaradyki, R. A. Mankowsky, and
T. W. Monnet. 1957. Amounts of salt needed to kill
mature trees. Mass. Ag. Expt. Sta. Bull. 509. 58 pp.

Hutchinson, F. E. 1966. Progress report No. l: The
influence of salts applied to highways on the levels of
sodium and chloride ions present in water and soil
samples. Project No. R1084-8. 26 pp.

Hutchinson, F. E., and B. E. Olson. 1967. Relationship
of road salt applications to sodium and chloride ion
levels in soil bordering major highways. Hwy. Res. Rec.
No. 193:1-7.

Hvass, N. 1968. Salt and roadside trees. Horticul-
tura 22:187-196.

51

52

53

54

55

56

57

58

59

6O

61

62

63

69

Ito, A., and A. Fujiwara. 1967. Functions of calcium
in the cell wall of rice leaves. Plant Cell Physiol.
8:409-422.

Kotheimer, J. B. 1967. Physiological factors in the
etiology and alleviation of salt induced decline of
roadside maples and pines. Diss. Abstr. Sec. B. 28:
760-761.

Kotheimer, J. B., A. E. Rich, and W. C. Shortle Jr.
1967. The role of ions in the etiology of maple decline.
Phytopathology 57:342.

Kotheimer, J. B., C. Niblett, and A. E. Rich. 1965.
Salt injury to roadside trees II. Progress report.
Forest Notes 85:3-4.

LaCasse, N. L., and A. E. Rich., 1964. Maple decline in
New Hampshire. Phytopathology 54:1071-1075.

LaCasse, N. L. and W. I. Moroz, ed. 1969. Handbook
stffects Assessment—-Vegetation Damage. PennsyIvania
State Center for Air Environmental Stu ies.

Laties, G. G. 1959. Active transport of salt into
plant tissue. Ann. Rev. Plant Physiol. 10:87—112.

Leggett, J. E. 1968. Salt absorption by plants. Ann.
Rev. Plant Physiol. 19:333-346.

Lumis, G. P., G. Hofstra, and R. Hall. 1971. Salt
damage to roadside plants. Ontario Dept. of Ag. and
Food Factsheet. AGDEX 275.

Marinos, N. G. 1962. Studies on submicroscopic aspects
of mineral deficiencies. I. Calcium deficiency in the
shoot apex of barley. Am. J. Bot. 49:834—841.

Marschner, H., R. Handley, and R. Overstrut. 1966.
Potassium loss and cha ges in the fine structure of corn
root tips induced by H -ion. Plant Physiol. 41:1725-
1735.

Miller, L. 1962. CaC12--salt snow and ice control
tests. Hwy. Res. Brd. Proc. 41:321-332.

Monk, R. W., and H. H. Wiebe. 1961. Salt tolerance and
protOplasmic salt hardiness of various woody and herba—
ceous ornamental plants. Plant Physiol. 36:478—482.

64

65

66

67

68

69

70

71

72

73

74

75

76

77

70

Nieman, R. H. 1962. Some effects of NaCl on growth,
photosynthesis and respiration of twelve crop plants.
Bot. Gaz. 123:279-285.

Oosting, H. J. 1945. Tolerance of salt Spray of plants
of coastal dunes. Ecology 26:85-89.

Parups, E., A. L. Kenworthy, E. J. Benve, and S. T. Bass.
1958. Growth and composition of leaves and roots of
Montmorency cherry trees in relation to the sulfate and
chloride supply in nutrient solutions. Proc. Am. Soc.
Hort. Sci. 71:135-144.

Prior, G. A., and P. M. Berthouex. 1967. Study of salt
pollution of soil by highway salting. Hwy. Res. Rec.
Wash. No. 193:8-21.

Rasmussen, H. P. 1967. Calcium and strength of leaves.
I. Anatomy and histochemistry. Bot. Gaz. 128:219-223.

Rich, A. E. 1971. Effect of de-icing chemicals on woody
plants. Forest Notes, Spring:26-27.

Rich, A. E., and N. L. LaCasse. 1963-64. Salt injury
to roadside trees. Forest Notes, Winter:3-5.

Richards, L. A. (ed.) 1954. Piagnosis and Improvement
of Saline and Alkali Soils. USDA HandboOk No. 60. '
160 pp.

 

Rios, M. A., and R. W. Pearson. 1964. The effect of
some chemical environmental factors on cotton root be-
havior. Soil Sci. Soc. Amer. Proc. 28:232-235.

Roberts, E. C., and E. L. Zybura. 1967. Effect of sodium
chloride on grasses for roadside use. Hwy. Res. Rec.
No. 193:35-42.

Ruge, U., and W. Stach. 1968. Injury to roadside trees
caused by thawing salt. Angew. Bot. 42:69-77.

. 1970. Salt injury to roadside plantings
studIed. Shade Tree 43:112.

. 1965. Salt injury to roadside trees. Plants
ana Gardens. 20:34-35.

. 1957. Salt spray injury along the New Jersey
coast. Shade Tree 30:2.

78

79

80

81

82

83

84

85

86

87

88

89

90

91

71

Sauer, Guenther. 1967. On damages by de-icing salts to
plantings along the federal highways. News Journal of
the German Plant Protective Service l9(6):81-87.

(Digest translation by D. A. Strassenmeyer.)

Schraufnagel, F. H. 1965. "Chlorides". Comm. on Water
Pollution, Madison, Wisconsin. 13 pp.

Schraufnagel, F. H. 1967. Pollution aspects associated
with chemical de-icing. Hwy. Res. Rec. Wash. No. 193:
22-23 a

Shaw, E. J., ed. 1965. Western Fertilizer Handbook.
Soil Improvement Committee, Calif..Fert. Assoc.,
Sacramento Calif. 4th edition. 74 pp.

Shortle, W. C., and A. E. Rich. 1970. Relative NaCl
tolerance of common roadside trees in southeast New
Hampshire. Plant Dis. Rprtr. 54(5):360-362.

. 1965. Side effects of salting for ice con-
trol. Amer. City 80)8):33.

Smith, W. 1970. Salt contamination of white pine
planted adjacent to an interstate highway. Plant Dis.
Rprtr. 54(12):1021-1025.

Snell, W. H., and N. 0. Howard. 1922. Notes on chemical
injuries to the eastern white pine (Pinus strobus L.)
Phytopathology 12:362-368.

Stecher, P. G., ed. 1968. The Merck Index. Merck & Co.,
Rahway, New Jersey. 8th editiOn. Pp. 191, 956.

Strong, E. C. 1944. Study of calcium chloride injury
to roadside trees. Quart. Bull. Mich. Ag. Expt. Sta.
27:209-224°

Traaen, A. E. 1950. Injury to Norway spruce caused by
calcium chloride used against dust on roads. Proc. Int.
Bot. Cong. 7:185-186.

Verghese, K. G., R. E. Hanes, L. W. Zelazny, and R. E.
Blaser. 1969. NaCl uptake in grasses as influenced by
fertility interaction. VPI. Blacksburg, Virginia.

Vogelsang, P. 1932. Effect of dust layers on roadside
trees. Amer. Highways 11:16-17.

Walton, G. S. 1969. Phytotoxicity of NaCl and CaCl2 to
Norway maples. Phytopathology 59:1412-1415.

92

93

94

95

96

97

98

99

100

101

72

Weast, R. C., ed.. 1968. HandbooksgflChemistry'and
Physics. The Chemical RubBer.Co., Cleveland, Ohio.
49th edition. Pp. B-186, B-246.

Wells, B. W., and I. V. Shunk. 1938. Salt spray: An
important factor in coastal ecology. Torrey Bot. Club
Bull. 65:485-492.

Wester, H. V., and E. E. Cohen. 1968. Salt damage to
vegetation in the Washington D. C. area during.the
1966-67 winter. Plnt. Dis. Rprtr. 52(5):350-354.

Westing, A. H. 1969. Plants and salt in the roadside
environment. Phytopathology 59:1174-1181.

Williams, M. C. 1960. Effect of sodium and potassium
on growth and.oxalate content of Halogeton. Plant
Physiol. 35:500-505.

Wittwer, S. H., and F. G. Tuebner. 1959. Foliar ab-
sorption of mineral nutrients. Ann. Rev. Plant Phys.
10:13-32.

Woolley, J. T., T. C. Broyer, and G. V. Johnson. 1958.
Movement of chlorine within plants. Plant Physiol.
33:1-7.

Wyman, D. E.- 1971. Shrubs and Vines for American

'Gardens. The Macmillan Co., New York.

Zelazny, L. W. 1968. Salt tolerance of roadside vege-
tation. Proc. Symp: Pollutants in the roadside en-
vironment. Pp. 50-56.

Zelazny, L. W., and R. E. Blaser. 1969. Effects of de-
icing salts on roadside soils and vegetation. Hwy. Res.
Rec. Wash. No. 335:9-12.

APPENDIX

SALT TOLERANCES OF VARIOUS woony AND
HERBACEOUS PLANTS

The following is a list of the salt tolerances of various
woody and herbaceous plant species compiled from a review of
the available literature on salt tolerance. Salt tolerance is
divided into three categories:'

1) General salt tolerance--tolerance to both soil salts
and salt spray.

2) Soil salt tolerance--salt tolerance as determined by
application of salts directly to the soil or by observ-
ations of salt damage in areas where soil salts but
not salt spray were a factor.

3) Salt Spray tolerance--salt tolerance as determined by
application of salts directly to the foliage or by
observations of salt damage in areas where soil salts
were not a factor.

The salt tolerances of the various species were rated as
follows:

VT--very tolerant
T--tolerant

MT--moderately tolerant
S--sensitive

VS--very sensitive

Ratings were based on injury symptoms and varied slightly
with the researcher.

This table is designed to indicate relative salt toler-
ances and is not based on any specific levels of salt either
in the soil or on the foliage. It can be used primarily as a
guide when selecting plants for areas where salt is a factor.
Local conditions should also be considered.

73

74

oaaafiuaoo

 

 

N 92 xooasan auauma3 adamnmouauan .9
9 m> m m> HH.m m>.m> xooasa: scaaau mamaacaaao amam9
9 m NH 92 aauw>nooua smowuaes mflaauaacwooo anan9
N m> saw amflamam apaooan .9
9 m saw .mmm msxa9
N 92 Na.m 9z.m> Hflmtmaamsoo Namawnaae amamuoosamm
n.N m>.m> mafia souoom mwuuma>amm .m
b m> w m NH m> mafia spans .m manouum .m
h m> AH m> mafia cam amoaflman .m
NH.m 92.92 mafia amouaosom amouacaom .m
9 9 mean aawuumad sumac .m
b 9 mafia ova: ems: .m
n 9 aswm Moan auaoflum>wc .m
N m> seam acoum mmNSm anneao macaw
h B> NH.w Ez.m> OUUHQM 05am mnmmcdm .m
.. m> NH 92 a E. moans. 3a.: 3530 .m
9.N 92.m> o m sesame assuoz moans macaw
N m> cooscau asao monsooonumoummao aflosqamauaz
N 9 sauna amaaammn mflaaaoumaa .A
9 9 Monumea9 aswmwuaa .4
N 9 NH m> roman anamouam macwoac xfiuaq
Na.m 92.92 99 9 Macao can suaummm mamwawmuw> msuamwasn
9 92 “seesaw .mmm manamHSSh
N m> haaon nmflamcm EDwHomasva NMHH
N m mmanmmo amamu cuasam muamwmwm mwuammoaaeaso
NH 92 m m> Ham Emmamm mosamaao moans
mmmmfi zmmmwmm>m nzm mmmmHZOU
.mam haumm .mam 990m .mam .saw aeaz SOEEOO aeaz Hmowsauom

mosauaH09 Baum

 

mBZdAm mbom0¢mmmm 92¢ M0003 mDOHm¢> m0 mmuz¢mm409 BQNm

oaaeHuaoo

 

 

NH 92 m m> noufim .mmm aHauam
N m MHHaQOOH>Ham «mesa auaowmm .4
N 9 humanaoH>Ham eschew mHHa>o .4
9 m> humanaoH>uam mammaHH4 nH>aaH .4
N m> anuaoa0H>uaa mHmm4 aHoHMHoamnm .4
N m> muuanaOHMHMm saHm4 MOHumwma HaHaoaaHas4
N 92 NH m> HaUHa Uaonamm assocH .4
N 9 HacHa aaHHssoaa2 ausman .4
OH.N 92.9 HapHa amamousm amoaHusHm maaH4
9 9> aa>aa£ mo aaH9 aEHmmHuHa manuaaHH4
9.N 9>.9> usauaanoamuon auH23 EssaumaooamHs naHsoma4
N 9> aHmaE ua>Ha> EsaHuaHua> .4
N m> aHmae aaHuaua9 ESUHHauau .4
N m> aHmaE aHmusso2 ESHMOHmn .4
N 92 aHmae cHonaHm esschHonaHa .4
9 9 NH.m 92.92 HH.m m>.m> aHmae Hamsm esumnooam .4
9.N 9.92 aHmaS Ha>HHm ESSHHacooan .4
n 9 92 NH m> HH m> .39.. e9. sauna .4
NH m> m m aHmaE aHOEmohm assaumHmocaamm .4
OH.9.N9.9>.9> aHmaE hasuoz macHoamuaHm .4
N m> aHmaE amaaammm EduaeHmm .4
9.N m>.92 NH 92 Haontxom oossmaa .4
N m aHmaE HmHHamuao2 EsaaHammommaoE .4
N 9 aHmaE 0:02 0:05 .4
N m aHmmE m.Hammouu HHmuac .> Humanoum .4
N m> aHmaE HSE4 MHMSSHm .4
N m aHaae cH>mo HHoH>mc .4
N m aHmaE Eaaoanom aHHOMHaHmuao .4
0H.N 92.95 aHmaE ammo: auumaaeao uao4
NH 9 aHoao4 .mmm aHomo4

mmmm9 mDODQHUmQ
.mmm Nemam .mmm HHom .mmm .emo asez eossoo asez HMOquuom

aucaHaH09 uHmm

 

 

GODGHOGOUIIXHQZMQRN

vaSSHuaoo

 

N m> anonuzan maaHssHm aHHOMHSSHa .0
OH.N m.m anonuza: 2mHHmam anaaaoawxo .O
oH.~ m.m guesses: caamaHmeHm mammoaos .o

N m choruses aHHabaH HaHHabaH .o

N m> it: ttt mHmaaaoamHum .U

N m> anon» Haamxooo HHHamImsuo .0

N m encased: namaam macHoaHaooo .o

9 m NH 9 chorusam .mmm mamaauauo

N m> unanHHm caxaam auaanoa .U

N m> uuanHHw oHoaHsHoo maoHoauaHoa .U
oH.N m.m> NH m> uHaQHHm aaaHHaba msHmuoo

N m> humane aaHHaaHou nae asanoo

m 92 canvas auaumam mHmaacasao mHaHaO

N m> munanxoam nHHauaaoHooo .O

N m> auuanxoan aaHmaosaU aowmaosao .U

N m> mnuaoxoas aaamouam mHHaHumsa mHuHaU

9 92 aaHauao amoHaamm amHauaU

N m usaamana SMOHHaE4 auauaac aaaaumau

“m 9 9 HH m> maoxoan xnanmasm aua>o amuau
HH m> saaoanos SMUHHaE4 asaHaHHonao asaHmHaO

N w saaosuos maaHxao aHHOMHouaav msHSHan maawmuau
0H.N m.m> NH m> m m> saananos aaamounm maHsuan asaHmHao

N m> SOHHQ mucHenom HHucHsaom .m

N m> ill tit maaomanam aHsuam

9 92 HH 9 noHHn memo aHHomeamom .m

N 92 w 92 nauwn aaamonsm aHacaam .m

9 92 HH 9 soHHo aosaU anaMHummam .m

HH 9 noHHn MoaHm ausaH .m

N m I... I... 325:. .m

N 92 nouwn acaeum HHaaaEua .m

HH 9 AOHHQ 30HHa9 mHmaaHaasmaHHa .m
vascHHCOOIImmmM9 mDODQHUmO
.mam maumm .mam HHom .mam .aaw aeaz GQBEOO aeaz HMUHaauom

aoaaHaH09 UHam

 

 

waflnquOUIIXanmmm4

caaaHuaoo

77

 

9.N m>.m> muuaoHSE aanz aoHa .2
NH 9 m 9> MHHaQHs2 .99m nauo2

m 9 aH994 mHuumabHHa .2

NH 92 aHmmanauo aaHnanHm auaooan .2

9 92 m m aHamanaHU .99m .2

9 m aH994 .99a maHaz

w w> aauu 9HH59 aHaMHmHHau conceaUOHHHH

N m> aHaso aaoHou maoHouwmasm Buchanan

9 9 uaaHa3.2mHHma9 aHmaH .b

9 9 NH.m m>.m> usaHas HOMHQ auaumam aHmHa maaHmab
oH.N 9.92 auonuxaantaam aoeeoo maoHoasanu aarmommHm
NH.m.m9>.9>.9 .umSOOHmaaoa maaHauon9 mHEHaaH moausaaaHHu .0

9.N 9.m unsoloaaon aoesoo nonpaaaaHHu .0
N 9> umaoloaaoa amaaamab MOHaoman aHmuHoaHu
m.NH.m92.92.m m 9> . 2mm aaauw auaHoaoaaH aoHaa>H9maa9 .9

N 9> 2am maHHaon9 macho .9

N m anaHHu0H02 .9
0H.N 9.9 new aaamousm HOHmHaaxa .9
N 92 Anna maaHsoHHaz aHHouHumsmaa .9

9 9 HH 9 2mm auHaz aaaownasa msaHxau9

N m> noaan .Ham maaHxao aHHowHOHHaav .m .9

N m> soaan .Hsm maaHuaO auaHSHoaH MOHua>HHm .9
oH.~ m.m> NH m> roman anemones ooeuo>HHm .9
N m> soaan Havaawuo mHHauaaHuo .9
9.N m>.92 NH 92 m m> noaan SMUHHaE4 aHHochcaum mama9
9 92 aosHso amaoHno aHaocmo

N m> suonuzas ms>uom aHHOMHQHoa .U

N m auozusan sancam aaawsmaaa .O

m m smashes: oauuoo someones .o
caSSHuSOOIIm9999 mDODoHumo

.mam woumm .mam HHom .mam .aaw aeaz SOEEOU aeaz HMUHsauom

aocaHaH09 uHam

 

 

UOHGHHGOUIINHQmemd

78

casawuaoo

 

N m> xao umaEHso aaauuam .0

N m Mao 9H9 mHHunaHa9 .0

N m> xao uaaumano soHHa9 HHmHaQaaHaase .0
9.N m.92 m 9 2ao Ham amuaaouoaa .0
N 92 auanuaanoae .0

N m> Mao aoaanaq HaaQHH .0

N m xao eauuuam aHH929ouaua2 .0

N m xao 9axua9 mHHHao .0

N m xao auHas 95a3m HoHoaHn .0

N m> NH 9 HH.m 9>.9> xao aanz anHa maaHaso

9 92 Haa9 .mmm m9999

9 9 muuacoaxoso aaaHaHmHH> .9
oH.N m.m> HH 9 manage xoaHm aaHuouam .9
N 9 huuano cHHo saa9ouam mapam .9

N m> muuana naHa2a2 naHaeaE .9

N 92 humane nuauua2 eaH>a .9
NH 9 m 9> MOOHH9M SQEEOU aoaHaaEHa maaau9

9.N 92.92 HH.m 9.m aa9ma mstaa0 macHoHaEauu .9
9 92 NH m> uaH9o9 mcuaneoq .aoHHaUH. aumHa .9

N 9 HaH9o9 xoaHm aumHa .9

9 92 HH 9 ,aa9ma naoouamuaq auausaoHoaaHm .9

9 9> NH 92 coozsouuou maUHouHao .9

N 9> NH 9 m 9> HaH9o9 mauw maaamasao .9

N 9> HaH909 aaHHouaU mHmaawaaao .9

N 9 NH 9 m 9> HaH909 Ha>HHm .aa>Ha. anHa .9

N 9 NH 9 HaH909 auH23 aQHa .9

9 9 NH 92 m m HaH909 .99m nsHs909

N m aauu asaHm consoq aHHOMHHaoa maaauaH9

N 92 saanauoo9os amaaa9ab nowa09a9 ammuno
oasewuaooutm9999 mDODQHoma

.mam mau9m .mam HHom .mam .aaw aEaz SOEEOU aEaz HaaHsauom

aoaaHaH09 uHam

 

 

UmflGHuQOUIIxHOmemd

79

paseHuaoo

 

N m> 2am aHauasoE maanaom aaaaanaox .m

N 9 -2ma aHauaaoe amaaa9ab aawa09an .m

N m> 2mm sHauasoE achasm aHanHauaH .m

~ m an. campuses eeoexmo moeuoma .m

N 9 can .auae macaw auooao .m

N 92 2mm SHauaaofi Season austEoo .m

N m> and .auce aaa9ousm aHHa9aosa .m

N 9 new case swan aanz aHua .m

9 9 2mm aHauaao2 .99m manuom

N m> aauu avomam amaaa9ab a09409an anon9om

N 9 .3_HaHmoaH9HS9 unaneaq aaaHuHanEaH .9 .m
~H.m .m>.m> 3oHHH3 mon some .9 .m

NH 9 30HHH3 HaHmo aaua9HS9 .m

N 92 soHHHs Hanson auoaauaam .m

9 9 3oHHH3 xaaHm aumHa .m

N 9 soHHHs aHuuHHm mHHHmaum .m

N 9 soHHHs aan9ao macHoan9ac .m
oH.N 92.92 soHHHs uaoo aau9ao .m
N 92 .3OHH93 Haapaaom auHHaa .m

N 9 30HH93 maathoaa9 aaHHacmmsa .m

N m> NH.m 92.9 30HHH3 EaumsoHHa9 .aaHHauuH>. aoHa xHHam

9 92 soHHH3 aaoHow .mHuuHH9. .a .m

N 9 3oHHHs auHsz anHa xHHam

N 9> umaooH pHeaH99 .mHHaoHeauh9. .9 .9
9.N 9>.9> NH 9 HH.m 9.9> umSOOH xomHm aHoaoaocsaa9 aHaHoom
N 9 anosuxosn aaHHssao MUHHs>ao asaeanm
9.N 9.m NH 9 HH.m 9.9> xao 9Ea3m sunny .0
N m NH 9 m 9> xoo smHHmam Manon .o

N m> xao aaaaa999 MOHaaaH99 .0
oasaHu900ttm9999 mDODoHoma

.mam 9am9m .mam HHom .mam .aao asaz soseoo aeaz HMOHaauom

aoaauaH09 UHam

 

 

GQSGHHGOUIINHQmemfl

80

caaawusoo

 

N m> auuanuso nHch Human .auoa9500. aaaHnHaHp .m

N m> anemones ummexaoao oHHsaaosuoHo .m

N m> muuanuan.muuanaH9ua9 HHaVHaenaauaun .m

N 9 muuanuan maaam aaaHaaan .m

N m huuanuan aoeHam auamaumma mwuaauam

m 9 coossuanuaon whose .aaaz. esaauouna aHaHeauH4

m 9 9uuaouaam HmHSIaas aoH929auaouon4

9 92 HH m .HacHa caona9m amomsu asaH4
mmommm

N m> eHa aaHHanHm souuaz aauonua .9 .D

9 9 eHa aaHHanHm aHHea9 .0

N 92 EHa aaHmmsm mH>aaH .D

OH.N 9.9 EHa nouoom aHQaHm .D

oH.N 92.m eHa oa>aaHtauOOEm MHHOMHSH9Ha0 .9

NH 9 m .9> EHa nouoom mHHuaa9Ea0 .D

9 9 HH m> eHa caOHHaE4 aaaownaea mSEHD

N a omoeHH mmmHumNm mHHssasuoHa .e

N m .savaHH aaaEHHU MHOHgosa .9

N 9 NH.N m>.m> :aoaHH moaHuaHuuHa ounouoo .9

9 92 HH m> 0003mmam aaaoHHaEa aHHH9

N m> new .9046 SHHOEHH> HHSHHQEHHb .m

N m -aaua aaH>Ham ©HH3 mHHaaHeuou .m

N 9 iii III aaHuouam .m

N m> 2mm aHauGSOE saHHanHm aHHOMHoanEam .m

N m> .4 :Hauaao2 9HuanaEaH9 aaaHmsuua9tomsu .m

N m> III III mHmaaaanmaazo9 .m

N m In- In- oHHoMHueH .m

oaSSHusoaltm9999 mDODoHomo

.mam 9au9m .mam HHom .mam .aao aEaz 008200 aeaz HMOHcauom

aoaaHaH09 uHam

 

 

UaSCHHGOUIINHQZM994

0asaHueoo

 

N m> Haumaacouoo aaa9ouam maeHuuamauaH Haumaaaouoo

N m> uHaQHHm amaaa9ab asaH0HonaHa m0H9H00

N m> unaQHHm aaowuas4 aaaaHuaea mSHmuoo
9.N m.m> 0003000 Hawmo 0am aHaMHaoHoum .0
oH.N m.m> oooseoo masuoooem assesses. .o
9 m 0003000 90H0 . amoeaaau .0

N m> ooosmoo axHHm sasosm .o

N m> ooosmoo moooonHos .HHaumoam. one. .o

N m> ooosmoo ooHuoon .eoHnHon. mnHo .o

N m> ooozsoo.mfisuoHanoe .NHmoHNHommms. eoHo .o

N m 0003900 aaHHaHa9 anHa asauoo

m 9 :Hamuaa3m aswumaua9 aHaou9500

N 9 aaaamtua00aHm asaomauonua mauaHou

9 m aoaHSU maHua30H9 aHHaaamaH maHa5oaaaco
OH.9.N9.9>.9> aauutaa9 aaHuanHHm maaomauooua aaamaua0
NH 9 I oceans aHuuom mauaHoaoaaH aosaumHHHau

1. NH m> m m x00 005500 asaHH>Ha95am maxam
8‘ N m muuanuan 505500 mHHamHa> .m
N m> -.9uuanuan HaHsomH9 HuaHnomHu .m

9 9 950nm.amaaa9ab maaH0am aann9ua9ouua .u .m

N m> NH.m m>.m> wuuaouaa amaaa9ah HHmuanaanu .m

N m> muuaouan amua0929 aoHuaanu .m

N 92 muuaouan Ha3onmHm amSOHno .m

N 92 humanuan aaauom aaaanox .m

N m> .9unanuan aaauwnauaHB .aaaaHH59 .m

N m> munaonan muaxoom Huaxoon .m

N m> MHHaQHao 0HMHH0 HH0HmuHo .9

N m> whuanuan xoaHm HaHa9acmam .m

N 92 munanuan o0aH0H00 HHaH0aam .m
0ascHuaoottmmDmmm

.mam 9059M .mam HHom .mam .aaw a5az 505500 aeaz HMUHaauom

aoeaHaH09 uHam

 

 

omnoHuqoonanozm994

0005H0500

 

OH.N 0992 0a>HH9 505500 anamH0> .H
NH 92 0a>HH9 maxa9 50aaxa0 .H
m 9 0a>HH9 H054 am5au055 .H
9 92 0a>Hu9 .99n 50H0m0wHH
NH 92 5550504 auasaa 5550500
9 m 5m00 900aam nHHHnaea aHN0H32H09
Ha9
NH.m 92.92 1H50n 05H9aauo 0000054 50050H9 .5 .n
m 9 Ha9H50n 05H9aa00 mHHa05oNHH02 .b
.aaaHHaN0Hm9.
w 9 Ha9H50n HaN0Hm9 mHm5a5020 m0ua9H50b
NH m> snuaouauaes oumHHHoeuua> xaHH
N 9 aau00Han saHuanHm 5ou05a0oH55 50005a005HHam
o _92 meansmnom Nnon seesaw .mHHNoeuomam. .H .9
9 as manammnom umonom «Hoosnouoe oHeummuom
NH m> 53500 aH99aa5H9 555H30HHam manHa9
.2 N m> m0595009 205090053 m0moo0una> .9
8. N m> III III m0HOHMH00a9 .9
N m a0595o0a uaaH0aoum m0HHomw0aH .9
N m aau0 aH0599m m0aa9ou0a .9
9 9 NH.m m>.m> 5m0005H500m m00aHa n0595o0m
N m> m05maaaHa 550004 a0aHHa050 .9
N m> III III. flggfim an“ em
N m> Iii tit axaHmaH m5am509 .9
N 92 m05maaaHa 900a50 aHOHHH0H05 .9
N m> In- nu- Hmmoenom .m
N 9> 9HHaQHa>HHm 000005500 .9
0H.9.N 9.9.9 NH.m 9.9 m 9> . a>HHo 509mm09 MHHOMH0m0maa m0amaaaHm
N m> 55050305 0a20H59 a050HH05H m0maa0au0
0a05905001im9090m
.mam 9059m .mam HHom .mam .5a0 asaz 505500 asaz H00H5a0om

ao5aHaH09 0Ham

 

 

.UUSGNHGOUIINHQmemd

83

000550500

 

N 0> 550505005 0005550 055500 .9
N 0 .550505005 955055050509 00550000955 .9
9.N 5.0.9: 5050503 5030 0505859 .9
N 92 550505005 50050550 00005050 .9
9.N 9>.92 550505005 50090509 00050505000 0055059
N 0> 550500559 0005550 00055000005050 .9
N 0> N5 92 550500559 0055000 .00550000 .9
N 0> 550500559 05550 000500505000 0505000599
N 0 5505050059 0005590 005059
N5 92 50509000059 .990 50509000059
N 9 .09505015005 00030 0055050500 .9
9 9 095050 5002 .990 005950005559
N5 9 50050050 50050050 505502
95505909 00550>5905509 005592
N 0> 505002 005505509 00559002
oH.N 9.92 - 05500090555 999. 50090509 500000599 .5
N m> m 9 .05500090505 50550009 .00550000 .5
N m> 05500090505 00555 05050955590 .5
N 0> .,0H500090505 009509 55009509 .5
N 9 0555 0003 505059505509 .5
N 92 III III 05955 .5
N 0 05500090505 305502 55305505 .5
N 0 05500090505 5054 5550002 .5
N 0 05500090505 50050005 5550050005 .5
N5.m 92.92 05500090505 00050909 00550909 .5
N m> 05500090505.95505500m 00050050>55 .5
N 0 05500090505 9550500030 00505000 .5
N 0 05500090505 00030 50550905900 .5

N 0 05500090505 05009 00553 .0554. 050050 .
9 9 05500090509 .9M0 05005505
000550500II090990
.909 90590 .909 5500 0509 505500 0502 500550009

005050509 0500

 

 

-.UG§550500IINHOZM99¢

84

000550500

 

o5.N 9.92 m 9 955053050 00550 00950055059590
N 0 0005500 050503000
NH.0.0 0>.0.0 005590 00000550> 500000550> .0

9 0 005590 0050509 0050505 9 0005590

0 9 .95505 0509909 00050950 0505059050

oH.N 0.0 50050 00555051009 00050005 .0
N 0 50050 50090509 05955 .0

N 0 50050 50055054 0505000500 00005500

05 0 9550550055 50090509 00000050059 00509
o5.N 9.0 0005 000909 000905 .9
N 0> 5055500030 0005595505 .9
NH.0.0 0>.0.0 0005 00050900 0505950505 .9

o5.N 0.0 0005 909 055500 0009
N 0 0505500 500553 5005509500 .9

N 9 9550500009 3050 500>55 .9

N 0> 0505500 50055 50090509 505955 .9

N 9 III III 0050500905 .9

N 9 0505500 500500 50505500509 .9

m 00 nun nu: 55050559 .5

N 92 9550500009 95990500 50000550>50 .9

N 9 0505500 50550550 5050500050 .9

N 9 0505500 500500 500500 .9

N 2 0505500 50055 50055054 5050055050 .9
05.N 9.9 . 0505500 055954 5055950 00559
9 9 00500 55059000 0555990 .9

N5.m 9.9 500530090 000505550 .9

m 9 00500 500050 055059 .9

m 9 00500 05059059 005005050 0059

000550500I|090990

.909 90590 .909 5500 .909 .500 0502 505500 . 0502 500550009

.005050509 0500

 

 

UMdfiHHGOUIIXHDmemd

85

000550500

 

 

H 92 0000 005000 05054
0 a 5000>555e 0o9055o50 00000500 .0
m 9 5000>552 50050 0050905004
5 92 00059 000 300005 5509 0050050 5050500505554
9. 0 5000954 305509 05500500 50009Hfl.
H 0 5500509 300002 050500059 0050009054
0 0 000590509 .990 05000594
5 9 0005900053 5500003 550550 .9
H 9 0005900053 5509 500095050 505990594
0025> 024 090>oo 020090 .0000090
0 92 050005 05004 00005050559 00009
N5 92 0500595 .500009500 0500595
0 95 .3 0550mm 0>0 .055009.0>0. 0500503
9.N 9.0 5005955055050 50090509 005090 .3
N 0 5055055> 95000509 05505 .>
N 0 5055055> 0050955509903 0500505 .3
NH 0> 5055055> .990 5055055>
m 9 , 95505300 00005I0505> 50555000>
N 9 5550500 505000I0>59 050500509 .9
m 9> III III 550005509 .9
m 9> 5550500 5095009 0059055 .9
N5.0 9.9 9550509 0055509 5550509
9.N 9.0> 00555 505500 05509H0> .0
9 9 00555 0050 00050900 00550909 050505050 0955590
N 0> , 9550550500 00005005550 .0
N 0> ;9550550500 05005050 5505005050 .0
000550500II090990
.909 90590 .909 5500 .909 .500 0502 505500 0502 500550009

005050509 0500

 

 

000550500nu55025990

 

86

000550500

N
N
N

B
B
B

m>

5 52
5 0
5 02
0 0
5 5
5 a
5 02
5 52
5 a
5 a
0 0
5 02
5 0
5 a
0 0
5 02
5 52
5 a
5 00

055> 950555002
955059503 0005550
5509050 959
5509550 000900559
099 .550509 005502
00059095 505550509
055005

905509

9555 900 95309

5>5 0055000

000009 005 95590050
000009 5N 95000509
000009 5509

000009 300002

095 0553 000505009
095 0553 000500
000590500

5055553 00030

, 00059 0505050
00059 0005509

909 0.5050>059
00059 000059
0500500

05055 55005002
05055 500050

00059 000009

05059 0059

5005505005 .5
505509555505 .5
00505550 505095

m5mo05m5555 .0
000050055500 00005
.005502. .9 .5
0550509 505505
05509000 055005
050950> 5000509
0>509 055500050509
.55505 050009
05505 . 9

.5m 95000505. .0 .9 .9

00005505050 .0 .9
5050050 0000009
00050050550 .9
0505000500 005959
0005500 0555050050
00005505 00505059
000505059 05590000
50590000 5000590
055005> 05005050
050909 0550550
00050950 0500500
0000559505 .9
0555055 .9
00050505000 005059
05550059 050500009

000050000u10025> 020 000>00 020020 .0000050

 

.909 90590

.909 5500

005050509 0500

0502 505500

0502 500550009

 

 

:;.0055H5500IINH929994

 

 

5 92 00053 . .,50>50000 50050559

5 0 50>050 055005 .500050959 05500 .5 .9

5 0 m 0 50>050 00553 050905 .9

5 0 m 0 50>050 009 00500059 .9

5 0 m 0 50>050 055055 50055095 .9

5 92 50>050 9550530500 5050059050 .9

m 9 50>050 0000055509 0050>50 505500559

5 9 5000000 550555 00050550 0050505090

5 92 00059 50000 005050000 050950> 5059500

5 92 099 .0500500 050000

5 0 005505 50555 05500509500

5 9 00059550550 5500002 0505500005 05550550009

0 9 5500009550 00050553 0000500550 0555050009

0 9 , 0005 0002 05050505059 000500509

0 9 5350000050 0550005909 0550005905 505099509

92 000590055 95000509 050500059 .9
m 9 00059550550 0000050 .0

0 000590055 500555 00550 009
7. 5 92 00059 9550505 0500905000 00050500 .9
8. 5 92 950500 0009 05005505050 05505059
0 9 0550009 0055595 0550009

5 92 00050 055500 200000550 50509000

9> m 9 5090050 0555955> 055000095509 00005005050509
5 92 50>050 00030 305509 05505505000 .2

5 92 50>050 5000 005055 .2

5 92 50>050 50509 00550 .0 .2

5 92 .50>050 00030 00553 0550 000055502

5 92 m 9 0050050 000500059 0>5000 .2

m 9 0050050 050559 0050559 .2

m 9 0050050 0o005xo50 0000500 .2

m 9 0050050 50500500 05050500500 09005002

00055unoouu0525> 020 099>00 nzoomw .0900090

.009 90590 .009 5500 .009 .500 0502 505500 0502 500550005

005050509 0500

 

 

UMdGHMdOUIIxHazmmmd

3.

8.

9.

10.

ll.

12.

88

APPENDIX REFERENCES

Bernstein, L. 1958. Salt tolerance of grasses.and forage .
legumes. USDA Ag. Information Bull. No. 194. 7 pp.

Buschbom, U. 1968. Salt resistance of aerial.shootsof
woody plants. I. Effects of chlorides on shoot surfaces.
Flora, Jena 157 B, pp. 527—61.

Butler, J. D., T. D. Hughes, G. D..Sanks and P. R..Craig.
1971. Salt causes problems along Illinois highways.
Reprint from Illinois Research.. University of Ill. Agric.
Expt. Sta. Vol. 13, No. 4.

Cordukes, W. E. 1970. Tolerance to road salt. Golf Supt.
Vol. 28:5,44.

. 1971.; Development of ground covers for highway
slopes. University of Minn. Dept. Hort. Sci. Ag. Expt.
Sta. Tech. Bull. No. 282.

Hanes, R. E., L. W. Zelazny, and R. E. Blaser. 1970. Salt
tolerance of trees and shrubs to.de-icing salts. HWy. Res.
Rec. wash. No. 335:16-18.

Lumis, G. P., G. Hofstra.and R. Hall. 1971. Salt damage to
roadside plants. Ontario Dept. of Agriculture and Food
Factsheet. AGDEX 275.

Monk, R. W. and H. H. Wiebe. 1961. Salt tolerance and
protoplasmic salt hardiness of various woody and herbaceous
ornamental plants. Plant Phys. 36:478-82.

.‘ 1970.. Salt injury to roadside plantings
studied. Shade Tree 1970. Vol. 43:112.

Sauer, G. 1967. On damages by de-icing salts to plantings
along the federal highways. News Journal of the German Plant
Protective Service. l9(6):81-87. (Digest translation by

D. A. Strassenmeyer.)

Shortle, W. C. and A. E. Rich. 1970. Relative NaCl tol-
erance of common roadside trees in southeast New Hampshire.
Plnt. Dis. Rptr. Vol. 54, No. 5:360-2. May.

Zelazny, L. W. 1968. Salt tolerance of roadside vegeta-
tion. Proc. Symp: Pollutants in the roadside environ-
ment. Pp. 50-56.

HICHIGQN STQTE UNIV. LIBRQRIES

mm

| U “H“! |||1||||l lllllll l|¥||||l||| H“ H

1293 04224641