Dichloroethyl ether for the control of the plum curculio on peach

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Title:
Dichloroethyl ether for the control of the plum curculio on peach
Physical Description:
Book
Creator:
Snapp, Oliver I
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030285644
oclc - 779492570
System ID:
AA00023071:00001

Full Text







,... YDEFIARMINT

AGRICULTURE
I BUREAU Of I
E NTOMOLOGY AMD /
\\fANT UARANTINE /




DICHLOROETHYL ETHER FOR THE CONTROL OF THE
PLUM CURCULIO ON PEACH

By Oliver I. Snapp, Division of Fruit Insect Investigations



Lead arsenate, the insecticide at present generally used for the
effective control of the plum curculio (Cono;.rachelus nenuphar Herbst) on
peach, has an injurious effect on the foliage, buds, budwood, and fruit of
peach trees under certain conditions. Injury caused by lead arsenate to
buds. budwood, or fruit directly reduces the peach crop, while the damage to
foliage may bring about premature defoliation, which interferes with the
proper nourishment of the fruit buds for the following season's crop and,
in cases of heavy defoliation, produces premature fall blooming. Because
of these objectionable features, investigations have been carried on at
the Fort Valley, Ga., laboratory to develop a suitable and effective sub-
stitute for lead arsenate in the control of this insect.

To eliminate the use of an insecticide on the trees, treatment of
the soil under the spread of peach trees to kill the plum curculio in the
larval and pupal stages has been included in these investigations for a
number of years. Preliminary laboratory experiments with dichloroethyl
ether were included in this phase of the project in 1937, and more extensive
experiments with this material in the laboratory, in connection with caged
peach tree, and in commercial peach orchards, were conducted during the
seasons of 1938 to 1941, inclusive. The purpose of this circular is to
report briefly on the favorable results of these experiments and to make
the information pertaining to the use of dichloroethyl ether available to
any who may want to try it for the control of the plum curculio attacking
peaches. .

.Results of Experiments

In laboratory experiments dichloroethyl ether, used at the rate of
1/3 fluid ounce in 1/6 gallon of water -(1/6 gallon of 1.5-percent emulsion)
per square yard of soil, was found to be effective against plum curculio
larvae, and that material at the rate of 1 fluid ounce in 1/6 gallon of
water (1/6 gallon of 4.5-percent emulsion) was found to be effective against


February 1942


E-558






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plum curculio pupae. During the season of 1939 only 1 plum curculio adult
emerged from 3 caged peach trees, each of which had been artificially infested
with approximately 465 curculio larvae, in addition to those that fell from
these trees, before the soil under each tree received 2 applications of
dichloroethyl ether--one at the rate of 1/3 fluid ounce in 1/3 gallon of
water per square yard of soil when most of the insects were present as
larvae, and one at the rate of 1 fluid ounce in 1 gallon of water per square
yard of soil when most of the insects were in the pupal stage. The next
year only 4 curculio adults emerged from 4 caged trees, each of which had
been artificially infested with approximately 350 plum curculio larvae, in
addition to those that fell from these trees, before the soil under each
tree received only 1 application of dichloroethyl ether at the rate of 1
fluid ounce in 1/6 gallon of water (1/6 gallon of 4.5-percent emulsion)
plus 0.2 percent of sulfated alcohol per square yard of soil. In 1941 a
total of only 13 plum curculio adults emerged from 4 caged peach trees, each
of which had been artificially infested with approximately 883 plum curculio
larvae, in addition to those that fell from these trees, before the soil
under each tree was sprayed with 1/6 gallon of 1.5-percent dichloroethyl
ether emulsion per square yard of soil, chiefly against the larvae, and with
1/6 gallon of 4.5-percent dichloroethyl ether emulsion per square yard of
soil, chiefly against the pupae.

In extensive experiments conducted in a commercial peach orchard
during the season of 1941, a program consisting of two applications of
dichloroethyl ether on the soil under the spread of the trees, together with
12 jarrings to catch overwintered adults, gave as good control of the plum
curculio as the regular schedule of lead arsenate sprays on the trees.
The first application of dichloroethyl ether was at the rate of 1/6 gallon
of 1.5-percent emulsion per square yard of soil directed chiefly against
the curculio larvae, and the second application was at the rate of 1/6
gallon of 4.5-percent emulsion per square yard of soil directed chiefly
against the pupae. No injury to vegetation under the spread of the peach
trees or to any part of the trees or foliage could be discerned from the
two applications of dichloroethyl ether on the soil, whereas trees that
had received the regular schedule of lead arsenate were from 90 to 95
percent defoliated on September 12, following an especially favorable season
for arsenical injury.

Description and Properties of Dichloroethyl Ether

Dichloroethyl ether, C4HCa120, is a colorless liquid with an ether-
like odor. It is soluble to the extent of 1.02 percent by weight in water
at 20 C. (68 F.), which is equivalent to 1/10 of a gallon of dichloroethyl
ethler dissolved in 12 gallons of water. It is extremely resistant to hy-
drolysis and is soluble in practically all oils and organic solvents.
Di.chloroethyl ether has a boiling point of 178.5 C. (353.3 F.), a flash
p.int of 185 F., and a vapor pressure at 20 C. of only 1.2 mm. It is
beforeore not very volatile. The molecular weight of dichloroethyl ether is
142.98, and its vapors are about five and a half times as heavy as air.







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The specific gravity of dichloroethyl ether (20/20 C.) is 1.2219. It
weighs 10.2 pounds per gallon and has been sellinF, for 17 cents a i.ounnJ
in 55-gallon drums or 20 cents a pound in 5-gallon lots.

Preparing Stock Emulsion of Dichloroethyl Ether

To avoid the breathing of undue concentrations of the vapor, the
emulsion should be prepared outdoors or in a well-ventilated room. It is
desirable that the air temperature be between 50 and 80 F. The stock
emulsion is prepared as follows: First stir 9 parts by volume of dichloro-
ethyl ether into 1 part by volume of potash fish-oil soap. A good gra-dc
of potash fish-oil soap should be used, that is, one without an excess of
caustic potash and containing approximately 30 percent of soap and 70
percent of water. Place the 1 part of potash fish-oil soap in a container
and work' the 9 parts of dichloroethyl ether into the soap by constant
stirring. Start by adding a very small quantity of the dichloroethyl
ether to the soap and completely stir this in before making another id-
dition. The ether should be added at intervals and each portion completely
worked into the soap before another is added, until the 9 parts of ether
have been worked into the 1 part of soap. When the fish-oil soap and
dichloroethyl ether have been thoroughly emulsified, add water slowly
with constant stirring until the emulsion measures twice the volume of
dichloroethyl ether used. For example, if 18 gallons of the emulsion
are desired, start with 1 gallon of potash fish-oil soap, to which add
slowly at intervals, with constant stirring, 9 gallons of dichloroethyl
ether. Then add water, as directed, until the total quantity measures
18 gallons. This is the stock emulsion and contains 50 percent of di-
chloroethyl ether. The stock emulsion is diluted with water before ise,
the amount of dilution depending on the stage of the insect against which
it is used, as is discussed later.

If the stock emulsion breaks down after preparation, this will
be indicated by the appearance of globules of dichloroethyl ether at the
bottom, or by a curdled mass or a layer of clear dichloroethyl ether at
the bottom, that cannot be readily remixed by moderate agitation. If this
occurs, the material must be re-emulsified. This can be done by pumping
the mixture from one container to another or back into the same container,
or by starting over again with a small quantity of potash fish-oil soap
to which small quantities of the broken-down emulsion are added slowly at
intervals with constant stirring.

Dilution

Table 1 gives the quantity of water to be added to the 50-percent
stock emulsion of dichloroethyl ether to make 100 gallons of diluted emul-
sion of the strengths found by experiments to be most satisfactory for
use against plum curculio larvae and pupae in the soil under the spread
of peach trees. BRARY

STATE PLANT BO




UNIVERSITY OF FLORIDA

3 1262 09230 3774
4 -

Ta':1i2 l.--Dilution of stock emulsion of dichloroethyl ether and strength
of diluted emulsion for use against plum curculio larvae and pupae in the
soil.


For use Quantity required to make Strength of
against-- 100 gallons of diluted the diluted
emulsion emulsion

Water 50-percent stock
__________ emulsion
Gallons Gallons Percent

Larvae 97 3 1.5

Pupae 91 9 4.5



When and How to Apply the Emulsion

The first application should be made after all the larvae have left
:hc fallen peach drops and entered the soil. This is usually some time
during the first 15 days o: May at Fort Valley in central Georgia. A 1.5-
percent emulsion should be used for the first spray and it should be applied
under the spread of the trees at the rate of 1/6 gallon per square yard of
soil. For peach trees in Georgia this will be at the rate of about 1-1/2
galluiis for small trees, 2 gallons for medium-size trees, and 3 gallons for
large trees.

The second application should he made when most of the insects
are in the pupal stage, which would be about 2 weeks after the time of the
first application. A 4.5-percent emulsion should be used for the second
spray and it should be applied under the spread of the trees at the same
rate as that for the first spray.

The overwintered plum curculio adults should be caught by jarring
in the spring, when dichloroethyl ether is to be used as a substitute for
leo.i ars3cnnte for the control or the pluni curculio attacking peaches.
However, it will not be necessary to pick up peach drops when the ether
is used, and this will ofsefl the expense of jarring for the overwintered
curculios.