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temperature within the rooms in which the cabinets were placed. The cabinet
in the 35° room had an average temperature of 43° and the one in the 45° room had
a temperature of 50°. In comparing storage losses in the modified atmosphere
with the losses in air, it was necessary to make allowance for these variations in
temperature. While the results are by no means conclusive, they indicate a
smaller storage loss in the modified atmosphere. It is obvious that this experi-
ment cannot be carried out satisfactorily until a small sealed room is provided
having its own refrigerating coil.

Fruit and Vegetable Drying. (C. I. Gunness in cooperation with Department
of Horticultural Manufactures.) A small electric dehydrator was built during the
summer of 1942 for use in the Department of Horticultural Manufactures. While
planned for experimental work, the drier is of a size and design which makes it
suitable for home use.

A variety of vegetables was dried during the summer and trials on the dr\ing
of cranberries are now in progress.

Poultry House Investigation. (C. I. Gunness and W. C. Sanctuary.) The
housing project for 1941-42 showed an average water content of the litter varying
inversely with the amount of insulation all winter from December 1 to March 11.
On March 11 the water content of the litter from the non-insulated, partially
insulated, and fully insulated pens was 36.6, 26.3 and 25.9 percent, respectively;
the average number of birds was 77, 82, and 84; the food consumption from
December 1 to February 9 was 24, 22, and 20 pounds per bird; and egg production
45, 42, and 41 eggs per bird. "Blue comb" disease and paralysis reduced produc-
tion and caused considerable mortality. Each pen started in the fall with 100
Barred Rock pullets.

Horizontal and vertical temperature gradients were taken under electric
hovers, some commercial and one home-made. The brooders producing the best
results have a rather even temperature gradient from a low point at the outside
edge of the hover to a high point in the center of the hover.

One commercial hover had a lower temperature over a rather large portion of
the central area. This has been associated with a depression in the litter in the
central area under the hover as if made by chicks crowding to keep warm. This
particular hover has had high mortality, associated apparently with this crowding,
on several occasions during severe cold snaps, sometimes early in the brooding
period and sometimes during the lattier part of the brooding period.

The study of soil heating cable to dry the litter in a brooder house equipped
with an electric brooder was continued during the winter of 1941-42. While the
litter can be dried by this means, it was necessary to rake the litter daih to get
full value from the heating. Otherwise, the dry litter near the cable becomes a
good heat insulator allowing very little drying at the top and permits caking at
the surface. The extra work required, together with relatively high cost of current
makes the practice impractical.


Charles P. Alexander in Charge

Investigation of Materials which Promise Value in Insect Control. (A. I.

Bourne and W. D. Whitcomb.) Work on a cooperative project on investigations
of dinitro combinations was concerned primarily with the effectiveness of such
combinations against outbreaks of European red mite during the growing season.

A surprisingly heavy infestation of red mite developed in commercial orchards
in practically all sections of the State. Evidences of mite abundance and begin-
ning of injury to foliage were noted by mid-June. The attack developed steadily
throughout June and reached its peak in most sections by late July and early
August. Heavy bronzing of foliage occurred in many orchards, even on varieties
which usually were not considered to be particularly susceptible.

Tests with a DN dust (a L7 dicyclohexylamine salt of DNOCHP) and a DN
spray (a dicyclohexylamine salt of DNOCHP + dispersing and wetting agent,
used at the standard recommended strength of IJ^ pounds per 100 gallons)
were made in nearly all the blocks of the college and station orchard, and in
several commercial orchards. L^niformly good control of the mites was furnished
by both DN dust and DN spray, and where the applications were made with due
care and under suitable spraying conditions no injury resulted.

Special studies of different strengths of the DN spraj- were made in a block of
Baldwin and Wealthy trees. The material was applied at the rate of 12 ounces,
16 ounces, and 24 ounces per 100 gallons. All treatments gave good control of
m.ites on both varieties. Some slight marginal burn was noted in a few cases,
but this was so slight and occurred with such irregularity that it could not be
definitely attributed to the treatment and was of no commercial significance.

Toxicity tests of the DN dust and of the DN spray upon 15 different types of
ornamental trees and shrubs resulted in no measurable injury to the foliage of
butternut, elderberry, flowering plum, willow, rose, ornamental crabapple, privet,
barberry, Norw^ay maple, red maple, evonymus (several varieties) or magnolia.
Sumac, raspberry, and grape showed slight to appreciable injury. Fortunately
these would seldom require summer application of insecticides of this type.

At Waltham a commercial DNOCHP material, known as DN-111 and con-
taining approximately 20 percent of the toxicant, was used at the rate of 24 ounces
and 12 ounces per 100 gallons of water on Baldwin apple trees infested with
European red mite. The spray was applied July 23 when the mites averaged 12
to 16 per leaf. Both dosages gave good control, and no serious injury to foliage
was observed although the margin of some of the tender leaves was slightly
scorched. As a result of these experiments and others, DN-111 appears to be a
very satisfactory material for the control of summer infestations of the European
red mite, and excellent control can be expected from sprays containing as little
as 12 ounces in 100 gallons.

Control of Cabbage Maggot. (W. D. Whitcomb, Waltham.) The natural
field infestation of cabbage maggot at Waltham was heavy and caused commercial
injury to 88 to 90 percent of the untreated plants of susceptible varieties such as
Golden Acre and Copenhagen Market.

The first eggs were found on May 1 which is about the average date for the
last 12 years.

A study of the relative susceptibility of 13 varieties showed 4 early varieties
and 3 medium or late varieties with more than half of the plants severely injured
or killed and more than 80 percent commercially injured, while 2 earh' varieties
and 4 medium or late varieties had less than half the plants severely injured or


killed and less than 80 percent commercially injured. The most severely injured
varieties were Copenhagen Market and Super-curled Savo>-; Early Jersey Wake-
field showed the least injury.

Tests to determine the possibility of reducing the amounts of corrosive subli-
mate or calomiel in treatments for combating the cabbage maggot during the war
emergency showed that two applications of corrosive sublimate at 1 ounce in 15
gallons of water (1-1920) was equal to or more effective than two applications of
this material at 1 ounce in 10 gallons of water (1-1280) which is the normally
recommended concentration. Caloniel-talc dust containing 2 percent calomel
was very nearly as effective as the dust containing 4 percent calomel (the normal
recommendation) when applied by the mound method; but was significantly
inferior to the 4 percent dust when applied twice with a hand duster.

Control of Squash Vine Borer. (\V. D. Whitcomb, Waltham.) As in previous
experiments, spraying with 1 percent \'olck plus nicotine sulfate 1-500 was the
most effective treatment.

A rotenone-copper oxychloride sulfate dust containing .75 percent rotenone
was also effective and distinctly more satisfactory than a pyrethrum-yellow
cuprous oxide dust containing 3 percent of a petroleum solution of pyrethrins.

A DNOCHP-gypsum compound containing 2C percent of the toxicant reduced
the borer infestation nearly two thirds but produced only slightly more mature
squash than the check. Vines treated with a calcium arsenate-copper oxychloride
dust (5.25 percent tricalcium arsenate) were more heavily infested with borers
than the untreated vines but produced the largest yield in the experiment, indi-
cating that a light borer infestation, especially after secondary roots have de-
veloped, does not seriously reduce the yield of mature squash.

Control of Striped Cucumber Beetle. (W. D. Whitcomb, Waltham.) With the
existing light infestation which produced only about one tenth as many beetles
as in 1941, a calcium arsenate-copper oxychloride dust (5.25 percent tricalcium
arsenate) gave 90 percent protection to cucumbers and complete protection to
melons, which is very encouraging in view of restricted use of rotenone during the
war emergency. Rotenone-copper oxychloride sulfate dusts containing .75 per-
cent and .5 percent rotenone respectively were about equally effective, the
former giving slightly better protection on the cucumbers and the latter on the
melons. It is evident that the dust containing .5 percent rotenone will be satis-
factory if available. A pyrethrum-yellow cuprous oxide dust containing 3 per-
cent of a petroleum solution of pyrethrins was less effective than the rotenone
dusts but generally satisfactory. On the other hand the same pyrethrum dust
without yellow cuprous oxide gave only about 50 percent protection, although
the yield of melons following the treatment was the greatest in the experiments,
apparently because of a partial control of aphids and other sucking insects which
spread mosaic.

Control of Onion Thrips. (A. I. Bourne.) In field tests with insecticides the
standard combination of nicotine sulfate and soap again proved superior to all
other treatments, giving 87 percent reduction of thrips. A commercial rotenone
solution proved nearly as effective and gave greater residual protection. A spray
composed of castor bean extractive proved ineffective, largely because of its oily
nature and poor wetting qualities. A pine oil derivative in a penetrating soap
gave 74 percent control. Its effectiveness was not materially increased when
derris was added. A commercial pyrethrum dust (Pyrocide) gave 70 percent
control, an excellent showing for dust application and good commercial control.
Fixed nicotine spray s were only moderately effective, but a nicotine tannate
spray gave 74 percent effective control. A nozzle adapted to deliver a solid-cone



type of spray proved much more satisfactory and gave better penetration than
the conventional hollow-cone spray.

Ladybeetles and other natural enemies of thrips did not appear in the fields
in sufficient numbers to keep step with the rapid increase in thrips during late
July, and there was no evidence of the presence of the fungus disease which usuaUy
appears in the fields in seasons when thrips are unusually abundant.

The Value of Control Measures to Supplement the Standard Spray Program
for Apple Pests in Massachusetts. (A. 1. Bourne.) The study of proposed substi-
tutes to replace or supplement present standard materials and practices was
shaped to give special attention to replacements for materials subject to curtail-
ment because of the war emergency. This involved a determination of the value
of certain non-arsenical compounds and a study of more effective timing of late
season applications.

In a study of the effect of pyrethrum on overwintering larvae of the codling
moth in their cocoons on the trees, a pyrethrum-kerosene solution was applied
to the rough, flaky bark of the main trunk and base of the larger limbs of a small
block of apples, early in April while the trees were still in dormant condition.
These trees received no other application for codling moth control. Collections
of both drops and samples from these trees showed less than one-fourth as n^any
apples with codling moth stings and entrances on the treated trees, as on the
checks. The pyrethrum-oil application caused no damage to bark nor retarda-
tion of seasonal development. It apparently had no permanent repellent action
to codling moth larvae as indicated b\' approximately the same number of larvae
collected in chemically treated bands, from both sprayed and untreated trees,
at the end of the growing season.

This treatment eliminates the necessity for most of the scraping of loose bark
from the trees and should prove very effective in penetrating the winter cocoons
of larvae hibernating in piles of prop poles. These often attract large numbers of
larvae and, since they are usually collected in piles at the edge of the orchard,
serve as potential centers of infestation often entirely ov'erlooked by the grower.

In orchard tests to determine the value of various non-arsenicals for codling
moth control, one application of a fixed nicotine (14 percent nicotine) replacing
lead arsenate in the 4th cover spray reduced codling moth damage to 1.5 percent
as compared with 4 percent following the present standard schedule. Fruit
from unsprayed checks in this block showed 19.4 percent injury by codling moth.

Where fixed nicotine replaced lead arsenate in the 4th cover spray and was also
applied in mid-August, samples of fru't at harvest showed less than 6 apples per
1,000 damaged by codling moth.

A modified schedule in which a commercial pyrethrum-rotenone combination
was applied in the 2d, 3d, 4th, and mid-August sprays practically eliminated
codling moth damage. Lead arsenate was used with this combination but at
reduced strength.

An application of fixed nicotine between the 2d and 3d cover sprays to furnish
protection between June 12 and July 9 gave increased protection against codling
moth, although the effect was not so pronounced as would be the case in a year
when codling moth presented a more serious problem.

All of these materials were used with the wettable sulfur for scab control, proved
entirely compatible with the fungicides, and held scab to less than 1 percent dam-
age while samples from unsprayed trees showed 92 percent scabby fruit.

Insecticides for the Control of European Corn Borer. (A. I. Bourne.) The
warm, dry weather in April stimulated corn borer activity and, as in the previous
season, promoted early pupation of the overwintering larvae. Field collections


in the Connecticut Valley showed 20 to 30 percent pupation by the first week of
May, and the first moths emerged on May 12. Emergence increased steadily to
a peak on June 8 with a gradual reduction during the next 10 days. Coupled with
the comparativeh small carry-over of borers because of the light infestation in
1941, this early moth emergence, in advance of the development of the corn,
resulted in a comparatively light infestation of early market sweet corn although
somewhat heavier than in 1941. There was, however, a substantial build-up
during the summer and a more normal infestation of the corn which matured in
late August and September.

In the experimental plots the insecticidal applications, based on the first
appearance of young, newly hatched larvae, were made on June 10, 15, 20, and
25. Precipitation during that period, while it totaled 2.8 inches of rainfall, was
so well distributed that there was very little interference with the treatments.

Because of the war emergency and the limited supply of rotenone available,
the sale of this material for use on corn was forbidden so that the field tests were
confined to a study of the value of nicotine bentonite and dual-fixed nicotine.

Results from spraying with nicotine bentonite (14 percent nicotine) indicated
a considerable increase in protection when 3 pounds per 100 gallons were used as
compared with 2 pounds, but no advantage when more than 3 pounds were used.
Protection was good in all cases. Dual-fixed nicotine dust again furnished good

From the commercial standpoint the contrast between the corn harvested from
treated and untreated plots was more pronounced than can be indicated by figures.
Many of the ears scored as "infested" in the treated plots contained very small
borers which had hatched after the last application but had scarcely penetrated
the husks. A large proportion of such ears could be salvaged. Infested ears
from the check plots, however, contained many large, fully developed borers;
destruction of the kernels was extensive; and most of the ears were worthless.

Potato Spraying Experiments. (A. I. Bourne.) The experimental plots were
planted May 4 and 5. The plants made an early start, received no serious set-
back to their steady growth during a long growing season, and were for the most
part alive and green until killed by frost on September 28 to 29, 146 daj's from
the date of planting.

Flea beetles appeared in large numbers as soon as the plants were up, uere
very abundant throughout June and early July, and again from late July until
mid-August. There were no serious infestations of other insects.

The plots were given 11 applications of spray between June 5 and August 25.
In view of the war emergency and the possible shortage of copper for agricultural
purposes, special attention was devoted to a study of different strengths of bor-
deaux, and one plot was given a complete schedule of 2 J^-2 J^-50 bordeaux mixture
to determine the protection furnished against disease and insect attack by the
reduced dosage.

Flea beetle injury was measured by the number of leaf punctures per square
inch of leaf area, and varied inversely with the strength of the bordeaux mixture.
In every case the addition of calcium arsenate to the bordeaux mixture reduced
the number of feeding punctures. The reduction was greatest (one half) in the
plots which received the half-strength bordeaux, and was only slight in the plots
which received the standard 5-5-50 bordeaux, indicating that the addition of the
arsenical was an important factor whenever the strength of lime in the bordeaux
was reduced.

Sufficient protection was furnished by all the different strengths of bordeaux to
keep the plants alive and vigorous throughout the growing season, and scarcely
a trace of blight was noted. In an adjoining plot which was sprayed with a com-


mercial neutral copper fungicide, the plants were badly riddled by flea beetle,
began to die down in late July, and a large proportion were dead by late August.
The yields in all the bordeaux-treated plots were very satisfactory.

The results in the plots treated with 23^-2 J^-50 bordeaux were very satisfactory
and encourage the hope that, during the present emergency at least, reasonable
protection from disease and insect pests may be secured with a considerable
saving in materials.

Investigations on the Effect of Insecticides on Honeybees. (A. I. Bourne and
F. R. Shaw). The investigations during 1942 were conducted along two main

L The use of materials that might be added to spray or dust mixtures to
repel bees. Of those used, creosote appeared to be the most effect've m repelling
the bees but Injured apple foliage. Tests are being continued to try to find some
material that will be effective as a repellent and yet be safe on plant foliage.

2. The effect on bees of materials used as ant poisons, together with an in-
vestigation of the danger of bee poisoning resulting from the use of commercial
ant baits. The ant poisons tested contained either thallium sulfate or some
arsenical, most commonly sodium arsenite. Because the arsenical compounds
killed the bees so quickly, there was less danger of the poison being carried back
to the hive than in the case of the slower acting thallium compounds.

Experiments with commercial ant traps, used as directed by the manufacturer,
indicate that very slight danger to bees will result if the ant poisons are in salve
boxes or similar types of containers. The use of sweetened ant baits exposed
openly would appear questionable, not only from the danger to bees but also
from the aspect of safety to man and other animals.

Naphthalene and Similar Compounds as Greenhouse Fumigants. (W. D.

Whitcomb and \Vm. Garland, Waltham.) Experimental fumigations using a
mixture of monochlor naphthalene 3 parts and flake naphthalene 1 part were con-
tinued at various relative humidities. Satisfactory control of the common red
spider mite occurred only after ^ ounce of the fumigant was vaporized in 1,000
cubic feet and the mites had been exposed for 3 hours. Fumigations at 50, 60,
70, and 80 percent relative humidity and 60°F. showed no significant differences
as the relative humidity was increased, indicating that this factor Is less important
than temperature, which has shown increased mortality at the higher tempera-

Biology and Control of the Apple Leaf Curling Midge. (W. D. Whitcomb,
Waltham.) In emergence cages in the insectary no midge flies emerged in 1942
from maggots collected in June and July 1941, while 67 percent of the maggots
collected In August transformed to flies in 1942.

Emergence of the first generation flies at Waltham was about two weeks later
than in 1941 and oviposltlon was negligible on the trees under observation.
Emergence of flies again occurred July 20-25 and August 8-15, and the greatest
oviposition of the season occurred August 18-27. Larvae were collected In bands
in large numbers on July 28 and on September 10, and precipitation exceeding 1
inch was recorded at each time. The influence of rain in causing the maggots
to leave the rolled leaves was very noticeable.

Treatment of the soil under lightly infested trees with naphthalene flakes at
the rate of 2 pounds per 100 square feet gave almost complete control of midge
flies for both the first and the second generations. Spraying during the height
of the oviposition period of the second generation, caused a measurable reduction
in the number of infested tips where a rotenone or a DN spray was used but no
reduction where a pyrethrum spray was used.


Control of Common Red Spider Mite on Greenhouse Plants. (\V. D. Whit-
comb, Wm. Garland, and W'm. E. Tomlinson, Jr., Waltham.) Studies of the pH
of the sap of several of the host plants of the common red spider mite showed that
the lower the pH of the plant sap the less time was required for the mite to de-
velop from hatching to adult. These results are based on investigations with
rose and carnation plants. Preliminary- experiments with tomato, bean, sweet
pea, snapdragon, gardenia, and chrysanthemum have been made and this phase
of the work will be continued.

Among the experimental sprats for the control of the common red spider mite
on greenhouse roses, a commercial mixture of gypsum and dicyclohexylamine
di-dinitrocyclohexylphenate containing 20 percent of the toxicant, applied two
or three times at weekly intervals, gave practically complete control when used
at the rate of 24, 20, or 16 ounces per 100 gallons of water with Ultrawet 1-1000
as a wetting agent. On unsprayed plants in the same bench, the number of
spiders increased 40 percent during the same interval.

A commercial spray known as technical mannitan laurate reduced the number
of live mites 89 percent in four applications at 1-400, and 73 percent at 1-600.
Two other rotenone materials gave fair control of the red spider mite and a third
material was ineffecti^■e.

Several of these materials were more effective against the red spider mite on
carnations than on roses.

Control of Plum Curculio in Apples. (W. D. Whitcomb, Waltham.) The
effect of different amounts of spray on the control of the plum curculio in apples
was studied by applying a measured quantity to apple trees of known size. An
application of 1 gallon per 100 square feet was significantly more effective than
an application of % gallon, but IM gallons per 100 square feet were not consis-
tently more effective than 1 gallon, indicating that the results might be influenced
by factors other than gallonage.

Cryolite, 4 pounds in 100 gallons, used as a substitute for the same amount of
lead arsenate, gave somewhat less control of the plum curculio in apples, and
caused very severe russet on Delicious apples.

Lead arsenate was used at the rate of 2, 3, and 4 pounds in 100 gallons of spray
on Northern Spy for protection against the plum curculio. Results indicated
that 4 pounds is necessary for satisfactory control where this insect is abundant.

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