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THE EFFECT OF SPRAYS ON THE
PHOTOSYNTHETEC

ACTMW OF SOUR CHERRY LEAVES

'i'hcsxs for the Degree. of M. S.
MlCHiCAN STATE COLLEGE.

Lyie M. Murphy
1939

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THE EFFECT OF SPRAYS ON THE PHOTOSYNTHETIC

ACTIVITY OF SOUR CHERRY LEAVES

by

Lyle Mayer Murphy

Thesis

Submitted in partial fulfilment of the requirements
for the degree of Master of Science in the
Graduate School, Michigan State College
Department of Horticulture

1959

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II.
III.

IV.

VI.

VII.

VIII.

TABLE OF CONTENTS

Introduction

Review of Literature
Materials and Methods
Presentation of Data
Discussion

Summary
Acknowledgment

Literature Cited

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29

INTRODUCTION

During the past thirty years, Michigan has become the leading
sour cherry producing region in the United States. The rise of this
industry was due largely to favorable soil and environmental conditions.
To maintain this rank as a leading state, the growers are confronted
with the ever important problem of controlling cherry leaf spot
(Coccomyces hiemalis). Previous to the past few years, the growers
have used either lime-sulfur or bordeaux mixture to control leaf spot
in a four-spray program. The results were, however, none too satis—
factory; lime-sulfur failed to give control in epidemic years, and
bordeaux, while giving good control of leaf spot, resulted in a
decreased size of fruit and at times serious defoliation of trees due
to copper injury.

In view of the fact that adequate control with lime—sulfur was
not obtained in some years and that bordeaux resulted in the production
of smaller fruit, some new spray materials have been introduced to
control leaf spot, these being the new low-soluble copper compounds.
Within the past five years, results obtained at the Michigan Experiment
Station revealed these new copper compounds to be superior to either
of the old standard sprays, and consequently, some of these compounds
are now recommended by the Station.

That certain sprays have a deleterious effect on the trees, both
chemically and physically, has been proved conclusively. It is
difficult to obtain a spray that is innocuous to the trees and at the
same time one that is successful in controlling the disease or insect

for which it is intended. With the advent of these new copper compounds,

- 2 -

questions arose as to the effect of these new sprays on the metabolic
processes going on continuously within the plant. How would they
affect transpiration, respiration, and the assimilatory activity of the
leaves? The purpose of this study was to reveal the effects these

Sprays have on the photosynthetic behavior of the sprayed cherry leaves.

REVIEW OF LITERATURE

The studies made on the photosynthetic activity of sour cherry
trees are very limited, and apparently no direct quantitative determin-
ations have been carried on. The investigations of this general type
previously reported and dealing with deciduous fruits have been made
largely with apple trees grown in greenhouses.

Hoffman (12) found that lime-sulfur, when applied to McIntosh apple
trees growing in the greenhouse, reduced the phothsynthetic activity
57 per cent. However, this harmful effect disappeared completely two
weeks after application. Hoffman (15) further observed that lime-
sulfur when applied to orchard grown apple trees reduced the photosynthate
produced. The reduction was greater under conditions of high temperatures
and these high temperatures also resulted in more marginal burning of the
leaves.

Christopher (5) reported that flotation sulfur caused a reduction
in carbon dioxide assimilation of orchard grown trees, but that the
reduction was not nearly as serious as that caused by lime-sulfur. Thus
he concluded that flotation sulfur was a safer spray to use in control—
ling fungous diseases on apple trees.

By enclosing entire trees in glass assimilation chambers, Heinicke

(11) studied the effect of lime—sulfur sprays on the foliage. His

_ 5 _

results showed that lime-sulfur did reduce carbon dioxide assimilation
temporarily but the trees regained their efficiency within ten days.
He concluded that while some sulfur burning of the leaves was evident,
this in no way could account for the reduction in photosynthetic
activity, but that lime—sulfur in some way reduced the assimilation
rate of normal healthy leaves.

The effects of sulfur sprays on McIntosh and Baldwin apple leaves
at various temperatures with controlled humidity were studied by Hyre
(16). His results revealed that lime-sulfur effected twice the
reduction in photosynthetic activity as did wettable sulfur. Eyre
also applied lime-sulfur to the lower surface only and to the upper
surface only of leaves and found that leaves which were sprayed on the
lower side only showed a reduction in photosynthesis comparable to that
of normally sprayed leaves. However, spraying leaves only on the upper
side resulted in but slightly reduced photosynthesis.

From the data reported above, it appears that lime-sulfur as well
as other forms of sulfur reduces carbon dioxide assimilation of apple
trees, although the reduction is not as marked with wettable and
flotation sulfur as with lime-sulfur. The apparent reduction in
photosynthesis could in part be accounted for by an increased rate
of respiration. Hoffman (15), however, carried on respiration tests
on leaves sprayed with lime-sulfur and stated that increased respiration
from lime—sulfur did not account for the marked net reduction in photo-
synthate.

Though no oil sprays were used in this study, it is of interest to

note the effect of oil sprays on photosynthesis. Young (50),Hoffman (l4),

- 4 _

and Schroeder (25) all reported that oils reduced the carbon dioxide
intake of leaves. This reduction was usually greater with increased
viscosity and increased percentages of oil in the spray. The trees did,
however, gradually recover from the effects of the oil but the recovery
became less with each succeeding application of Spray.

The effect of calcium arsenate in combination with different buffers
on the carbon dioxide intake of Jonathan apple leaves was studied by
Overholser and Overley (18). They found that three sprays of calcium
arsenate and "safeners" applied at 14-day intervals did not adversely
affect the leaves, as measured by the carbon dioxide intake. In case
the spray materials themselves might have absorbed some carbon dioxide
and in this way masked any reduction in leaf activity, sprayed pieces of
cardboard gave results comparable to air checks.

Hoffman (12) included bordeaux mixture in his studies with apple
trees and reported that bordeaux sometimes caused a slight reduction
in carbon dioxide intake while at other times there was no reduction.

He was of the opinion that any reduction was due to some physical effect
of the bordeaux precipitate rather than to a chemical disturbance like
that of lime-sulfur since the leaves regained their former efficiency
when the spray material was washed from them.

Clore (5) applied bordeaux mixture, copper sulfate, and lime as
separate sprays to Delicious apple leaves. His results revealed that
bordeaux and copper sulfate alone did not reduce carbon dioxide
absorption when compared with the check trees. Lime, however, did
reduce carbon dioxide absorption. Clore stated that at the time of

sampling, the leaves were so well covered with spray that the green

_ 5 _

color of the leaves was not visible except upon close observation.

Childers (2) sprayed tomatoes with bordeaux mixture, oil, and a
combination of bordeaux and oil. His data showed that under drought
conditions, bordeaux-sprayed tomatoes showed a marked reduction in
plant growth, yield, and size of individual fruits. The combination
oil-bordeaux spray showed similar results, but they were not so
striking. The oil sprays failed to decrease size or yield of tomatoes
and even increased terminal growth. Childers suggested that the
increased growth may be due to the oil's lowering transpiration and
as a result, the plants had more water for growth.

Upon running carbon dioxide assimilation tests on tomatoes,
Christopher (4) reported that bordeaux and lime used alone failed to
reduce carbon dioxide absorption. A copper sulfate solution caused
visible Spotting of leaves and as a result of this injury, a marked
reduction in carbon dioxide absorption.

~Rasmussen (25) analyzed sour cherries for their total solids
content. The indices which he obtained indicated that the total
solids content of lime-sulfur—sprayed cherries was 5-5 per cent lower
than that of bordeaux—sprayed cherries. Furthermore, the lime—sulfur-
sprayed cherries ripened later than did the bordeaux-sprayed cherries,
while the bordeaux-sprayed cherries were smaller than those sprayed
with lime-sulfur.

From the above literature review, one is not justified in stating
the effects of bordeaux on leaf activity. It is apparent, however,
that bordeaux mixture is not as toxic to leaf metabolism as is lime-

sulfur. Since bordeaux-sprayed cherries are smaller in size but at

the same time are higher in total solids content, one would suppose
that bordeaux has little effect in depressing the photosynthetic
rate of cherry leaves. The work of Hoffman, Clore, Childers and
Christopher have indicated this in other genera. A hypothesis
advanced might be that bordeaux has more influence on transpiration

than on the photosynthetic activity.

MATERIALS AND METHODS

Trggs. The trees selected for the study were fiveayear-old
Montmorency cherry trees, vigorous in growth and uniform in size. On
April 27, three—fourths of a pound of ammonium—sulfate was applied
to each tree, being distributed as uniformly as possible around each
tree. Five different plots made up of four trees in each were laid
out, and the blossoms were removed from all trees on May 5. Deflorating
was done to insure uniform samples.

‘SEEgyg. The five different plots were sprayed as follows: Liquid
lime-sulfur (2} gallons per 100), Cupro K (5 pounds per 100 gallons),
Coposil (5 pounds per 100 gallons), bordeaux mixture (6-8-100), and
checks. I

Liquid lime-sulfur was used in this study because it is One of the
old standard sprays used to control leaf spot. Frequently, lime-sulfur
is used as a basis for comparison when any new material enters the
market. Most of the studies made on the effect of sprays on trees have
dealt with lime-sulfur, and in most cases, lime-sulfur has been found
to reduce the assimilatory activity of the leaves. Rasmussen (21)
reported that lime-sulfur sprayed trees have foliage superior to

bordeaux—sprayed trees, but that lime-sulfur did not control leaf spot

in epidemic years.

Cupro K was used in the studies because it was one of the first
low soluble copper compounds used for the control of leaf spot in
Michigan. It gave satisfactory control of leaf spot according to
Cation (l) and caused little if any dwarfing of the fruit according
to Rasmussen (25). Cupro K is a copper oxychloride containing 25 per
cent metallic copper and is manufactured by the Rohm and Haas Company,
Philadelphia, Pa.

Coposil was used in the experiment because it was found to cause
less injury than any of the bordeaux mixtures [Rasmussen (25i7.
Coposil is a copper ammonium silicate containing 20 per cent metallic
copper and 4 per cent metallic zinc and is manufactured by the
California Spray Chemical Corporation, Richmond, California.

A 6-8-100 high-calcium lime bordeaux was used because it has
been recommended as a fungicide for the control of leaf spot on sour
cherry trees but was discontinued since it caused serious dwarfing
of the fruit and premature defoliation of trees under Michigan
conditions.

The remaining plot was used as a check and received no spray
applications during the study.

The four-spray program, as recommended by the Michigan Experiment
Station, was followed in this work [Rasmussen, Hutson and Cation (2417.
This program consists of four applications: petal-fall, when most of
the petals have dropped; two-weeks application, should be completed
within two weeks after petal-fall; four—weeks application, should be
completed two weeks after application two; after-harvest, just after

the fruit is harvested. The petal-fall spray was applied May 15, the

- 8 _

two-weeks spray May 50, the four—weeks spray June 14, and the after-
harvest spray July 18.

All sprays were applied with a 6—gallon~a-minute pump delivering
4—5 gallons per minute at the nozzle with a pressure of 500 pounds.
The trees were covered as completely, uniformly, and timely as was
possible.

Discussion of Methods. No completely satisfactory method for determin—

 

ing photosynthetic activity has been presented. A little understanding
of what takes place within the plant during photosynthesis along with
the other plant processes that are going on simultaneously is all that
is needed to see why the above statement is obvious. As Miller (1?)
pointed out, photosynthesis is no simple reaction but a series of such
and any results that are obtained in measuring photosynthesis will
depend on what place in this series of reactions the data were obtained.

Of the methods employed to measure photosynthesis, the following
are the most used: (a) carbon dioxide absorption, (b) liberation of
oxygen, (c) saccharification, and (d) dry weight accumulation. Since
no one of these methods measures the same thing, it is no wonder that
conflicting results are obtained.

Coincident with photosynthesis are the processes of respiration
and translocation which render photosynthesis determinations difficult.
According to Miller (17), photosynthesis is the absorption of carbon
dioxide and formation of carbohydrates with the release of oxygen, and
respiration is the absorption of oxygen and the subsequent breaking
down of carbohydrates with the liberation of carbon dioxide. Thus, it

is apparent that no two methods will yield the same results.

_ 9 _

Most of the work reported in the review of literature was done with
the carbon dioxide absorption method as described by Heinicke and
Hoffman (9). Briefly, this method is based on the fact that green
leaves in the presence of light absorb carbon dioxide from the air.
The amount of carbon dioxide in the incoming and in the outgoing air
is accurately determined and the difference is regarded as apparent
photosynthesis for that given leaf area.

Another much-used method of measuring the photosynthetic activity
is the dry weight increment method. According to Miller (17), this
method was first used by Sachs in 1884. With a few modifications, the
method today is essentially that which Sachs used. He removed one-half
of a leaf blade at the beginning of the experiment, obtained the dry
weight, and later removed the second half of the leaf and obtained its
dry weight. The increase in dry weight during this time represented
the photosynthate produced during the day. Sachs recognized that
this was not a true figure since translocation and respiration were
in no way considered. Thus Sachs added to this day gain the night
loss and considered this to be respiration and translocation. This
method is not entirely correct since it assumes that respiration and
translocation proceed at the same rate during the day as they do at
night and this supposition is not exactly true.

The method was improved according to Miller (51) when Ganong in
1908 devised a punch which could remove a definite leaf area (one
square centimeter). The use of this punch enabled one to obtain more
uniform samples since large veins and midribs can be omitted from
the samples. Ganong was of the opinion that the removal of these

punches did not interfere with the normal functioning of the leaves.

- 10 _

The main sources of error in the dry weight method, according
to Thoday (28), are: (l) the shrinkage in the area of leaves during
the day, (2) the asymmetry of leaves used in sampling. Thoday considered
the method satisfactory for rates of increase greater than two milligrams
per square decimeter per hour. He insisted, however, that the results
were not comparable to results obtained by the gasometric methods since
they did not measure the same things. Thoday (29) later reported that
apparently translocation occurs during the day as well as during the

night.

Spoehr (27) considered the dry weight method none too reliable.
He likened this means of measuring what goes on in a leaf during the
day to the business carried on in a bank. One is not justified in
assuming that the difference in total accounts from morning till night
is any more of an index to the total transactions concurred at a bank
during the day than to assume the same for plant leaves.

Thus any method used to measure photosynthesis is not going to
be entirely satisfactory. The results will have to be taken as
relative and not final. Pickett (19) demonstrated this by comparing
three methods of measuring photosynthetic activity. He found that
the dry weight increment method gave the highest results, followed
by the absorption tower method, and the saccharification method
gave the lowest results. He concluded that each method can be
criticized and the data obtained are relative and not absolute.

Sampling. For the present studies, the dry weight increment
method was employed since field results were desirable and this method
offered the simplest means for obtaining such results. The absorption

tower method involves considerable expense to be set up in the orchard

- 11 -

and since many samples were to be taken, the dry weight method was
deemed the most desirable.

The punch used in the study removed an area of 0.5144 square
centimeters from each leaf. This is considerably smaller than the
square centimeter punch used by Ganong in 1908 and Miller (17),
nevertheless, it was found in the present studies that a smaller
punch could remove more uniform samples by omitting large veins.

All samples were taken from leaves on spurs of the previous
season's growth located on the median portion of the shoots. Leaves
on spurs at the apex of the shoots and leaves on spurs at the base
of the shoots were found to vary considerably and as a result were
not used in the studies. Cowart (6) had previously reported that
the photosynthetic activity was greater at the apex of the shoot than
at the base.

Two trees were studied under each treatment. A sample consisted
of 50 punches, one punch being taken from each of 50 different leaves.
Samples were taken thrice daily: at 5:50 a.m., 2:00 p.m., and 7:00 p.m.
The increase in dry weight during the day was obtained by subtracting
the weight of the 5:50 a.m. sample from either the 2:00 p.m. sample
or the 7:00 p.m. sample, depending upon which was the greater. Assum-
ing that translocation and respiration proceed at the same rate during
the day as during the night, the loss in dry weight during the night
was added to the day gain to secure the total photosynthate produced
during the day. Six samples were taken from each leaf, and this
constituted a run which lasted for two days. Consequently, a new run

was started every two days.

-12-

Since it was not practical to obtain a uniform deposit of spray
material on all leaves, it was necessary to remove this spray material
immediately preceding sampling. This was done by washing only the
area taken as a sample. At the start of the study, the washing was
done with a weak acid solution, but this resulted in a burning of the
leaves apparently by the liberation of metallic copper. During the
remainder of the study, the leaves were washed with distilled water.

Immediately following collections, all samples were placed in
glass vials which were tightly stoppered. As soon as all samples were
taken, they were brought to the laboratory, weighed, dried in an oven
at 900 C. for 24 hours by which time they reached a constant weight.
They were then removed, placed in a desiccator, cooled, and weighed
again. The weights were recorded and calculations were to be made
later.

After the samples had been weighed a second time to obtain their
constant dry weight, they were placed in crucibles and ash determina~
tions were made. Thoday (29) reported that changes in dry weight may
consist, in part, of ash to as much as 5 per cent. Furthermore, it
was next to impossible to remove all the spray residue from the leaves
and since the 6-8-100 bordeaux ash weighed the most and had the greatest
deposit of copper throughout the studies, it may be assumed that by
correcting for ash, this source of error was eliminated. No quantitative
determinations were made, however, to support this assumption.

The crucibles were placed in a muffle furnace for 12 hours at a
temperature of 4000 C. The crucibles were removed, and ash weights
were recorded. The weights for the ash were then subtracted from the

constant dry weights to give the net dry weight. It was these net dry

_ 15 _

weights which were used to compute the photosynthetic activities
for the various treatments.

Only healthy leaves were used in these studies. No injured
leaves were included in the samples. Thus, it should be pointed out
that this study does not pertain to the entire tree since, following
the first spray application, many copper injured leaves fell to the
ground and in this way Were lost to the tree. Such was not the
case with lime—sulfur; no injury resulted from its use in any of the

Sprays.

PRESENTATION OF DATA

Dry weight determinations for a period of six days were made on
eight trees before any spray materials had been applied. These were
(made to see if any significant differences existed in the photosynthetic
rates of the leaves before starting differential treatments. The data
for these determinations are presented in Table 1. It would appear
that trees C and E had a photosynthetic rate significantly less than
the remaining trees, but the mathematical analysis did not bear this
out. By analysis of variance, it was shown that no significant
differences existed among the averages for the eight trees before any
spray was applied.

Since each treatment was applied to two trees, all the data here—
after presented are on the basis of the daily averages of the two trees
in each plot. The data in Table 2 present the average photosynthate
produced each day before any spray material had been applied. Again the
figures show that no significant differences existed in the photosynthetic

efficiency of the trees.

-14..

In Table 5, data are presented showing the average amounts of
photosynthate produced by the leaves of the two trees in each plot
after the first spray application. The leaves of the bordeaux—sprayed
trees had a photosynthetic rate significantly less than the leaves of
all other treatments, and the average rate of the leaves of the Cupro K—
aprayed trees was significantly less than that of the check trees.
Furthermore, the rate of the bordeaux-sprayed leaves was significantly
(highly) less than the rates of the lime-sulfur—sprayed and check
leaves (Table 4).

The lime-sulfur-sprayed leaves with a daily average of 8.01 gms
of dry matter produced were significantly less efficient than the
check and Cupro K-sprayed leaves after the second spray application.

The photosynthetic rate of lime-sulfur~sprayed leaves, when compared

to the rate of the Coposil-sprayed leaves, was a border line case and
no conclusions can be drawn from these data. There was no significance
between the photosynthetic activity of the bordeaux-sprayed leaves and
of leaves of the other treated plots (Tables 5 and 6).

The data, presented in Table 7, are for the photosynthate produced
by the leaves of the trees after the third spray had been applied. From
the data in Table 8, it can be stated that the mean for the lime-sulfur-
sprayed leaves was significantly (highly) less than the means of the
check, Cupro K-sprayed, and bordeaux—sprayed leaves. The Coposil—sprayed
leaves had a mean significantly (highly) less than the mean of the
Cupro K‘sprayed leaves. The mean of the bordeaux-sprayed leaves was
significantly less than the mean of the Cupro K-sprayed leaves, and
the mean of the Coposil-sprayed leaves was significantly less than the

mean of the check leaves.

_ 15 -

The summaries for the total photosynthate produced by the leaves
of the trees after three applications are presented in Table 9 and
the mathematical analysis is given in Table 10. The leaves of the
trees sprayed with lime-sulfur had a mean significantly (highly) less
than the means of the check and Cupro K—sprayed leaves. The lime-
sulfur mean was also significantly less than the Coposil mean. The
means of the Coposil—Sprayed leaves and the bordeaux-sprayed leaves
were significantly (highly) less than the means of the check and
Cupro K-sprayed leaves.

After dry weight determinations had been made for the firSt
three sprays, the leaves on spurs on the median portion of the previous
season's shoots were depleted, and in order to insure uniform samples,
leaves for further sampling had to be obtained from new trees. As
previously mentioned, four trees were laid out in each plot, so two
new trees were available for further study, but no determinations had
been made on these trees previous to spraying, and thus it was desired
to have some data on these trees before the fourth spray was applied.

Dry weight determinations were run for eight days before the
fourth spray was applied. The data are presented in Table 11 and the
analysis is given in Table 12. Significant differences existed among
the trees and as a result the data obtained after the fourth spraying
can be compared only with those obtained from the same trees previous
to this spraying.

In Table 15 are presented figures on the photosynthate produced
by the leaves of the trees after the fourth spray was applied. By
comparing the data in Table 13 with those in Table 11, it is obvious

that the means of the check, bordeaux-sprayed, Coposil-sprayed and

_ 15 _

Cupro K-sprayed leaves were higher after the fourth spray was applied
than before and that the mean of the lime-sulfur—sprayed leaves was
considerably lower. Thus, this further substantiates the hypothesis
that lime-sulfur reduces the photosynthetic rate toward the latter
part of the season.

From these data it is apparent that lime—sulfur applied as a spray
‘to cherry leaves early in the season did not reduce the photosynthetic
rate of the leaves. However, following its second application, lime—
sulfur did reduce the photosynthetic activity materially, though the
leaves appeared to regain their former efficiency within a three—day
period. Following the third spray, the photosynthetic activity was
reduced considerably and this time the leaves did not appear to regain
their former activity within eight days. Following a fourth application,
the photosynthate produced was reduced, but this reduction, much like
that following the second application, lasted only four days, after
which time the leaves appeared to function normally.

The bordeaux-sprayed leaves showed a marked reduction in photo-
synthate produced following the first Spray. The leaves did not
appear to recover from this injurious effect. Following the second
application, the photosynthetic rate was likewise reduced, though
the reduction was too small to be of any significance. The same can
be said of the third spray. After the fourth spray, the bordeaux-
sprayed leaves actually increased their photosynthetic activity;
however, this increase in photosynthate produced was general with all
treatments, and this can not be attributed to any stimulatory action

of the spray.

_ 17 _

Spraying with Coposil did not result in a decrease in the ability
of leaves to synthesize food materials following the first or second
application. However, following the third application, rate of photo-
synthesis was significantly lower than in the case of Cupro K-sprayed
or check leaves. After the fourth spray, the leaf efficiency increased,
though this was not, apparently, due to any influence of the spray
material.

The Cupro K-sprayed leaves showed a reduction in photosynthate
produced following the first spray application, but during the
remainder of the season the leaves functioned normally in this respect.

It is not surprising that (6-8-100) bordeaux in the first applica-
tion materially decreased the photosynthetic rate of the leaves, for
observations at that time showed that copper injury was evident. The
lower surfaces of the sprayed leaves were bronzed and the leaves had
a tendency to curl slightly toward the dorsal surface.

Copper injury was accentuated by weather conditions immediately
following the first spray application. At that time, unsettled,
cloudy days with considerable rainfall prevailed. Such conditions are
not conducive to sulfur injury as pointed out by Dutton (7), and may
explain the fact that lime—sulfur-sprayed leaves did not show decreased

photosynthetic efficiency.

_ 13 _

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Total photosynthate produced per day by leaves of unsprayed

trees. Expressed as grams per square meter leaf area.

Trees
Date A B C D E F G H

May 7 8.67 15.88 11.04 12.08 7.75 15.79 11.88 12.62
May 8 6.47 12.19 8.59 14.11 6.89 18.00 10.08 10.08
May 9 7.10 9.12 4.55 4.24 5.18 2.65 6.47 8.90
May 10 7.75 8.70 5.48 8.06 5.40 5.08 5.67 8.57
May 11 8.49 6.68 2.44 5.94 5.10 0.42 5.48 9.56
May 12 4.57 7.95 0.65 6.05 2.55 5.18 0262 6.27
Total 45.05 58.52 52.51 50.48 52.65 45.12 56.20 55.60
Mean 7.17 9.75 5.42 8.41 5.44 7.19 6.05 9.27
Table 2. Average total photosynthate produced per day by leaves of the

two trees in each plot previous to spraying. Expressed as

grams per square meter leaf area.

Treatment Temperature Character

_‘_ of day“ _

Date Cupro K Coposi 6-8—100 Lime— Maxi— Mean
sulfur mum

May 7 11.28 11.56 11.77 12.25 89 78 partly cloudy
May 8 9.55 11.55 12.45 10.08 82 76 partly cloudy
May 9 8.11 4.29 5.92 7.69 84 75 clear
May 10 8.22 6.77 4.24 6.02 84 72 cloudy
May 11 7.59 4.19 2.76 6.42 79 72 partly cloudy
May 12 6.26 5.54 2.76 5.45 84 74 partly cloudy
Total 50.79 41.50 57.90 45.91
Mean 8.47 6.92 6.52 7.65

 

 

 

 

 

 

 

- 19 -

 

 

 

 

 

Table 5. Total photosynthate produced per day by leaves after first
spray application. Average of two trees in each plot;
expressed as grams per square meter leaf area.
Treatment Temperature Character
of day
Date Cupro K Coposil Check 6-8-100 Lime- Maxi- Mean
sulfur mum
May 20* 15.58 11.72 15.27 9.28 15.45 72 68 cloudy
May 24 8.91 10.02 10.77 5.25 9.76 82 68 partly cloudy
May 25 6.56 9.97 7.85 5.08 6.25 89 76 partly cloudy
May 27 12.56 ’ 9.24 15.99 11.50 15.90 80 74 cloudy
May 28 7.65 9.57 12.52 7.57 11.98 84 75 partly cloudy
May 29 10.55 10.56 11.54 10.80 11.18 80 70 clear
Total 59.57 61.08 75.74 47.28 66.48
Mean 9.90 10.18 12.29 7.88 11.08

 

 

 

 

 

 

 

 

*Although the first spray was applied May 15, no determinations were made
until May 20 because weather conditions would not permit sampling at
that time.

Table 4.

hy leaves after first spray application.

Analysis of variance of total photosynthate produced per day

 

r‘

 

Source Degrees of Sum of Variance 1 F Standard error
freedom squares
Total 29 245.81
Treatment 4. 65.58 15.90 6.51**
Days 5 151.79 26.56 10.46**
Error 20 50.44 2.52 1.59

 

 

 

 

 

 

**Significant at the one per cent level.

In order for the difference between two means to be significant, the
difference should be 1.92 at the 5 per cent level and 2.62 at the l
per cent level.

_ 20 -

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 5. Total photosynthate produced per day by leaves after second

spray application. Averages of two trees on each plot;

expressed as grams per square meter leaf area.

Treatment Temperature Character
of day
Date Cupro K Coposil Check 6-8-100 Lime- .axi— Mean
1 sulfur

May 50 12.02 12.67 11.51 10.60 6.90 84 72 partly cloudy
May 51 11.86 9.74 9.55 7.42 7.22 80 72 cloudy
June 1 12.19 11.02 10.81 7.27 6.90 78 66 cloudy
June 2 6.05 8.70 8.71 7.91 8.16 75 64 partly cloudy
June 5 5.85 6.57 4.41 4.40 5.79 77 64 partly cloudy
June 7 12.74 11.78 11.46 8.58 8.59 67 61 partly cloudy
June 8 12.57 11.72 9.12 9.75 7.48 67 58 partly cloudy
June 9 8.70 7.54 15.21 15.17 12.14 76 62 clear
June 10 9.76 7.75 8.48 9.50 8.55 78 70 cloudy
June 15 11.98 10.59 10.61 15.67 8.59 75 60 clear
Total 102.50 97.88 99.65 94.07 80.10
Mean 10.25 9.79 9.97 9.41 8.01
Table 6. Analysis of variance of total photosynthate produced per day

by leaves after second spraying.

1, 1
Source Degrees of Sum of Variance F Standard error
freedom squares

Total 49 ‘ 519.02
Treatments 4 52.50 15 2.20
Days 9 155.00 1‘ 00 4.59**
Error 56 155.52 71 1.95

 

 

 

 

 

 

**Significant at the one per cent level

In order for the difference between two means to be significant, the
difference should be 1.75 at the 5 per cent level and 2.55 at the 1 per
cent level.

-21-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 7. Total photosynthate produced per day by leaves after third

spray application. Average of two trees in each plot;

expressed as grams per square meter leaf area.

Treatment Temperature' Character
of day
Date Cupro K Coposil Check 6—8—100 Lime- Maxi- Mean
sulfur mum

June 14 14.05 10.55 11.88 9.86 5.04 76 64 cloudy
June 15 11.99 7.52 11.56 10.59 7.89 84 72 partly cloudy
June 16 7.85 2.75 6.20 6.52 4.98 69 65 cloudy
June 20 15.52 5.52 15.56 11.92 6.75 85 70 clear
June 21 15.47 6.95 10.71 14.68 5.56 84 72 cloudy
June 22 8.48 9.58 8.80 6.62 6.25 85 72 partly cloudy
June 25 7.57 6.91 6.65 5.72 5.84 86 74 clear
June 28 9.97 8.45 6.79 7.94 7.21 72 60 clear
June 29 10.81 8.06 7.05 4.18 4.61 75 62 partly cloudy
Total 97.51 66.07 82.98 77.85 51.91
Mean 10.85 7.54 9.22 8.65 5.77
Table 8. Analysis of variance of total photosynthate produced per day

by leaves after third spraying.

Source ,Degrees of Sum of Variance F Standard error
freedom squares

Total 44 588.22
Treatments ' 4 152.55 55.08 8.99**
Days 8 158.15 17.27 4.69**
Error 52 117.74 5.68 1.92

 

 

 

 

 

 

‘**Significant at the one per cent level

In order for the difference between two means to be significant, it must

lae 1.84 at the 5 per cent level and 2.48 at the l per cent level.

_ 22 -

 

 

 

 

Table 9. Summary of total photosynthate produced by leaves of trees
after three spray applications (from May 7 to June 29).
Application j Treatment
Cupro K Coposil Check 6-8-100 Lime-sulfur
First 59.57 61.08 75.74 47.28 66.48
Second 102.50 97.88 99.65 94.07 80.10
Third 97.51 66.07 82.98 77.85 51.91
Total 259.58 225.05 256.57 219.18 198.49
Means 10.58 9.00 10.25 8.77 7.94

 

 

 

 

 

 

Table 10.

Analysis of variance of summary of total photosynthate produced
after three applications.

 

 

 

 

 

 

 

 

 

 

Source Degrees of Sum of Variance i F Standard error
freedom squares 3

Total 124 1041.11

Applications 2 69.07 54.54 15.65**

Treatments 4 107.16 26.79 10.59**
Days 22 1 422.94 19.22 7.60**
Application 1

x treatment 8 119.64 14.96 5.91**
Error 88 522.29 2.55 1.59
**Significant at the one per cent level

In order that two means be significantly different, the difference between
the two means must be 0.89 at the 5 per cent level and 1.18 at the l per

cent level.

- 23 -

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 11. Total photosynthate produced per day by leaves of new trees
before the fourth spray was applied. Average of two trees in
each plot; expressed as grams per square meter leaf area.

1
Treatment Temperature Character
of day

Date Cupro K Coposil Check 6—8-100 Lime- Maxi~ ”can

sulfur mum

July 6 8.80 7.05 7.57 17.06 16.48 65 56 clear

July 7 7.59 8.54 9.55 15.84 14.57 67 55 partly cloudy

July 9 5.99 7.90 6.51 11.05 9.15 49 46 cloudy

July 10 5.05 7.16 1.75 5.61 5.55 62 52 partly cloudy

July 14 4.56 12.45 11.78 10.12 9.91 54 50 cloudy

July 15 6.17 9.75 8.15 8.16 9.06 58 52 cloudy

July 16 4.25 10.44 10.02 14.84 10.02 68 55 clear

July 17 1.57 8.57 10.86 10.44 9.86 60 52 cloudy

Total 45.54 71.66 65.75 89.10 82.18

Mean 5.44 8.96 8.22 11.14 10.18

Table 12. Analysis of variance of total photosynthate produced by new
trees previous to fourth spray application.

Source Degrees of Sum of Variance F Standard error
freedom squares

Total 59 515.57

Treatments 4 154.14 58.55 5.87**

Days 7 175.51 25.07 5.82**

Error 28 185.72 6.56 j 2.56

 

**Significant at the one per cent level

In order for the difference between two means to be significant, the
difference should be 2.60 at the 5 per cent level and 5.51 at the 1
per cent level.

Table 15.

-24-

Total photosynthate produced per day by leaves of trees after
Average of two trees in each plot;
expressed as grams per square meter leaf area.

fourth spray application.

.w—o...‘ .o

 

a“

 

 

 

 

 

 

Treatment temperature Character

of day

Date Cupro K Coposil Check 6-8-100 Lime— Maxi— Mean
sulfurt mum

July 18 5.79 15.58 9.97 16.62 11.50 65 57 cloudy
July 19 0.52 7.55 6.65 8.94 6.56 78 68 cloudy
July 20 5.55 10.44 12.56 15.62 6.52 67 61 cloudy
July 21 5.28 2.12 10.05 10.91 4.66 62 56 cloudy
July 22 11.77 14.15 15.16 15.90 9.91 66 57 partly cloudy
July 25 11.62 11.77 12.99 15.78 10.50 59 56 cloudy
Total 58.15 59.59 67.14 79.77 §49.65
Mean 6.56 9.95 11.19 15.50 8.28

 

 

 

 

 

 

 

- 25 -

DISCUSSION

The results obtained in this study are in the main in accord
with those reported by other investigators. Temporary significant
differences were found in the photosynthetic rates of leaves sprayed
with various materials. However, the reduction in the photosynthate
produced did not last during the entire period of the study, and in
the case of lime—sulfur-sprayed trees, the leaves usually regained
their former efficiency in three to eight days.

Though statistically significant differences were found among the
several treatments studied, other factors are obviously of more
importance in the functioning of cherry trees and their subsequent
production of good craps than the influence of spray materials on
photosynthetic efficiency. Among the more important of such factors
are; vigor of the tree, weather conditions, soil types, fertilization,
pollination and fruit setting. Evaluation of fungicides commonly used
in the cherry orchard should be on the basis of their efficiency in
control of diseases and their effect on fruit size through their
influence on transpiration, rather than on the basis of any consider-

able influence on photoaynthesis.

_ 25 -

A study of the effects of certain fungicides on the photosynthetic

activity of sour cherry leaves showed:

1.

CN
0

That lime—sulfur dil not reduce photosynthesis after the first
spray had been applied, but did reduce the photosynthate produced
after the second, third and four spray applications. The leaves
apparently recovered from the effect of the spray three, eight and
four days respectively after it had been applied. The reductions
were great enough, however, so that highly significant differences
resulted from the use of the spray. The toxic effect became more

evident with each succeeding application.

That 6-8—100 bordeaux significantly reduced the photosynthate
produced as a result of the first spray application, but during
the remainder of the season, though some reduction in photosynthesis

was evident, the reduction was not significant.

That Cupro K significantly reduced the photosynthetic activity of
the leaves following the first spray. Coposil-sprayed leaves

showed no significant reduction at this time. Following the second,
third, and fourth spray applications, Cupro K-sprayed leaves showed
no reduction in the photosynthate produced. Likewise, Coposil,
though followed by some reduction in leaf activity following the
second and fourth spray, did not significantly reduce photosynthesis.
However, after the third spray, Coposil did significantly reduce the
photosynthate produced. Thus it appears from this study that the
new copper compounds are superior to lime-sulfur from the standpoint

of photosynthetic efficiency.

_ 27 _

In view of the fact that the reductions in photosynthetic activity
were only temporary and not continuous throughout the season, it
is evident that sprays for the control of leaf spot on sour cherry
leaves should be selected more on a basis of their fungicidal
value, of their apparent injury to the foliage, and of their

effect on transpiration, than of their effect on photosynthesis.

_ 23 _

ACKNOWLEDGMENT

The writer wishes to express his sincere appreciation to
Prof. E. J. Rasmussen for his assistance in planning the study as
well as helping with the Spraying, to Dr. J. W. Grist for his
assistance in outlining the method used as well as the use of his
laboratory for the studies, to Dr. W. D. Baten and Mr. J. I.
Northam for their cooperation in analyzing the data presented, and
to Mr. Ben Stuckey for his assistance in obtaining the samples in

the field.

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(2)

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(10)

(ll)

_ 29 -
LITERATURE CITED

Cation, Donald .
New copper sprays for control of leaf spot. Mich. Agr. Exp.
Sta. Quart. Bul. Vol. 19(5):l25-l52. 1957.

Childers, N. F.
Some effects of sprays on the growth and transpiration of
tomatoes. Proc. Am. Soc. Hort. Sci. 55:552-555. (1955). 1956.

Christopher, E. P.
The effect of flotation sulfur spray on the carbon dioxide
assimilation of apple leaves. Proc. Am. Soc. Hort. Sci.
55:149—151. (1955). 1956.

Christopher, E. P.
Carbon dioxide assimilation of the tomato. Proc. Am. Soc. Hort.
Sci. 54:527—555. (1956). 1957.

Clore, W. J.
The effect of bordeaux, copper, and calcium sprays upon carbon
dioxide intake of Delicious apple leaves. Proc. Am. Soc. Hort.
Sci. 55:177—179. (1955). 1956.

Cowart, F. F.
Apple leaf structure as related to position of the leaf upon
the shoot and to type of growth. Proc. Am. Soc. Hort. Sci.
55:145—148. (1955). 1956.

Dutton, W. C.
Spray injury studies. 1. Injuries from summer applications on
apples. Mich. Agr. Exp. Sta. Sp. Bul. 218. 1952.

Dutton, N. C. and Farish, L. R.
Comparisons of high-calcium and dolomitic hydrated limes in
bordeaux, zinc-lime, and iron—lime on cherry and peach. Proc.
Am. Soc. Hort. Sci. 55:186-190. (1955). 1956.

Heinicke, A. J. and Hoffman, M. B.
The rate of photosynthesis of apple leaves under natural
conditions. Part I. Cornell Agr. Exp. Sta. Bul. 577. 1955.

Heinicke, A. J. and Childers, N. F.
Influence of respiration on the daily rate of photosynthesis
of entire apple trees. Proc. Am. Soc. Hort. Sci. 54:142-144.
(1956). 1957.

Heinicke, A. J.
How lime-sulfur spray effects the photosynthesis of an entire

tenayear-old apple tree. Proc. Am. Soc. Hort. Sci. 55:256—259.
(1957). 1958.

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Hoffman, M. B.
The effects of certain spray materials on the carbon
dioxide assimilation by McIntosh apple leaves. Proc. Am.
Soc. Hort. Sci. 29:583-595. (1952). 1955.

Hoffman, H. B.
Carbon dioxide assimilation by apple leaves as affected
by lime-sulfur sprays. II. Field Experiments. Proc.
Am. Soc. Hort. Sci. 50:169-175. (1955). 1954.

Hoffman, M. B.
The effects of several summer oils on the carbon dioxide
assimilation by apple leaves. Proc. Am. Soc. Hort. Sci.
52:104—106. (1954). 1955.

Hoffman, M. B.
The effect of lime-sulfur Spray on the respiration rate of
apple leaves. Proc. Am. Soc. Hort. Sci. 55:175—176. (1955).
1956.

Hyre, Russell A.
Effect of sulfur sprays on the photosynthesis of apple leaves
in a controlled environment. Phytopath. 28:10. 1958.

Miller, E. C.
Plant Physiology. McGraw-Hill Book Co. New York. 1951.

Overholser, E. L. and Overley, F. L.
The effect of Spraying apple leaves with certain less used
materials upon their carbon dioxide intake. Proc. Am. Soc.
Hort. Sci. 52:95—96. (1954). 1955.

Pickett, W. F.
A comparison of three methods of measuring photosynthetic
activity of apple leaves. Proc. Am. Soc. Hort. Sci. 55:152-
154. (1955). 1956.

Pickett, W. F.
The relationship between the internal structure and photo-
synthetic behavior of apple leaves. Kans. Agr. Exp. Sta.
Tech. Bul. 42. 1957.

Rasmussen, E. J.
Effect of some copper and sulfur fungicides on the tree and
fruit of Montmorency cherry. Mich. Agr. Exp. Sta. Quart.
Bul. 19(5):l52-l42. 1957.

Rasmussen, E. J.
A prOgress report on comparisons of high-calcium and high-
* magnesium limes in bordeaux on sour cherry, and in zinc-lime
and iron-lime mixtures on peach. Proc. Am. Soc. Hort. Sci.
54:279-284. (1956). 1957.

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Rasmussen, E. J.
Unpublished data. Mich. Exp. Sta., East Lansing. 1957.
Rasmussen, E. J., Hutson, Ray, and Cation, Donald
Spraying calendar. Mich. Agr. Exp. Sta. Ext. Bul. 154.
1957.
Schroeder, R. A.
The effect of some summer oil sprays upon the carbon dioxide
absorption of apple leaves. Proc. Am. Soc. Hort. Sci.
55:170-172. (1955). 1956.
Snedecor, G. W.
Calculation and interprets ion of analysis of variance and
covariance. Collegiate Press, Inc. Ames, Iowa. 1954.
Spoehr, H. A.
Photosynthesis. Chemical Catalogue Co., New York. 1926.
Thoday, D.
EXperimental researches on vegetable assimilation and
respiration. V. A critical examination of Sachs! method
for using increase of dry weight as a measure of carbon
dioxide assimilation in leaves. Proc. Roy. Soc. B.
82:1-55. 1909.
Thoday , D .
Experimental researches on vegetable assimilation and
respiration. VI. Some experiments on assimilation in the
open air. Proc. Ray. Soc. B. 82:421-450. 1910.
Young, G. W.

Fish oil sprays as affecting the carbon dioxide intake by
Jonathan apple leaves. Proc. Am. Soc. Hort. Sci.
52:101—105. (1954). 1955.

 

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