September 1942 .. E-576
BU REAU Of
METHYL BROMIDE SOLUTION STUDIES: COLLAR TREATMENTS FOR NURSERY STOCK
By Heber C. Donohoe, Division of Control Investigations l/
Since April 1940 the laboratory for tests of treatments for the Japan-
ese Beetle has been engaged in field studies with methyl bromide solutions
in an effort to develop treatments for use in the administration of the
Japanese beetle quarantine. Until the autumn of 1941 the work was concerned
with solutions of methyl bromide, alcohol, and water prepared in an open
drum with more or less stirring. The procedure, with various modifications,
was patterned after that developed by Livingstone, Easter, and Swank (2)
and used in quarantine treatments for the white-fringed beetle (3). Data
were accumulated on treatments effective against Japanese beetle grubs in
turf, in heeling-in areas for nursery stock, in field beds of potted plants,
and for areas enclosed by metal collars suitable for use in treating the soil
about individual items of nursery stock in field rows.
,In September 1941 the laboratory cooperated with R. D. Chisholm and
L. Koblitsky, of the Division of Insecticide Investigations, at Moorestown,
N. J., in a study involving methods for the preparation of methyl bromide
solutions. A summary by Chisholm and Koblitsky (1) of the data obtained
from these studies is the subject of a separate paper.
In brief, the data indicated that solutions of methyl bromide and
water, either with or without alcohol dissolved in the water, could be pre-
pared in a closed system under head pressure, from the initially volatilized
methyl bromide, at substantially less cost and with better standardization
of solution strength than was possible with the open system of preparation
previously used. Loss of methyl bromide from the open system occurred at
every step of preparation and was critically affected by watex temperature.
There was no opportunity for loss during closed-system preparation, and
;/ In cooperation with the Division of Japanese Beetle Control. The
writer is especially indebted to George F. Kerbey and E. Howard Phillips
for assistance in the work discussed.
about 90 percent of the methyl bromide entered into solution regardless of
water temperature. Frequently the loss of methyl bromide from open-system
solutions is believed to have exceeded 50 percent by the time ofwithdrawal
for use. Although pressure is required during preparation of closed-system
solutions, this can be released after preparation with little subsequent
reduction in concentration during the interval of time necessary to apply
These findings, while largely preliminary, were promising enough to
demonstrate the value of their application in field-mortality tests during
'he autumn of 1941. Owing to the season's unprecedented drought, the field
studies were considerably restricted. The information obtained is promis-
ing and has indicated the advisability of basing most of the laboratory's
future studies on closed-system solutions.
MATERIALS AND METHODS
Closed-system apparatus: The vessel used in field studies is an 82-
gallon, reinforced, export-type steel drum provided with a bushing welded
in the head, in which is installed a water spigot with threaded outlet.
With the drum on its side, bung up, the spigot is at the lower edge of the
Larrel. An 18-inch lcingth of garden hose attached to the spigot reaches to
the bottom of the sprinkling can used in withdrawing solution for use.
For treatments involving, an original stock solution of methyl bromide
and alcohol, a mixing chamber was devised which releases liquid through the
hung cap into a tube which extends to within 1 inch of the bottom of the drum.
This chamber consists of' a graduated glass tube of 1,100 cc. capacity, which
is capped with a brass cover, through which 1 pound of methyl bromide is
released into a tube discharging at the bottom of the chamber, and which
is provided with a hung and removable plug for the introduction of alcohol
and a valve Thore ad'_justment of pressure during the introduction of the
methyl bromide. Through an orifice in the brass base plate the stock under
val7e control is with rawn into the tube which passes through the bung cap
of the drum. In work to date, if methyl bromide alone is to be used, a
standard applicator is attached to a tee in the line just above the valve,
and the required charge is released into the same tube.
With the desired quantity of water in the drum and all thread fittings
rubbed with brown laundry soap to insure an easily broken but airtight
seal, the bung cap is set down tight on a rubber gasket, and the required
charge of stock or of methyl bromide alone is introduced. The drum is gently
rocked Lack and forth for 5 minutes to facilitate formation of the solution.
The cap seal is then broken and the solution is ready for use. Solutions
are withdrawn into garden sprinkling cans of the desired size and are applied
therefrom by pouring over the edge as quickly as possible.
Closed-system studies to date have been limited to treatments designed
for nursery stock and have involved units of 1/3-square-yard surface area
enclosed by circular metal collars set into the soil surface just enough to
Certain procedures in collar treating and subsequent digging have beexi
indicated as advisable, based on experience with open-system tests. SoI
surfaces within collar areas must be somewhat mulched and practically fre
from weeds and grass. After dosage application, the soil surface music be
leveled by hand (rubber gloves being worn), with as little agitation of 1he
liquid as possible, to insure complete surface coverage, at least of those
dosages applied at the rat- of 1 gallon per 1/3-square-yard collar. This
necessitates a loose suriace soil, For dosage above 1 gallon per collar,
complete coverage usually occurs with the soil smoothed prior to treatment
Surface vegetation impedes leveling and breaks up the solution stream at
application. This in turn is believed to result in increased escape of
methyl bromide before penetration into the soil. Collar areas are dug
approximately 24 hours after treatment (20 hours minimum) and for convenience
are held in open 1/2-bushel produce hampers for at least 4 days before the
initial examination for mortality. This insures inclusion of the post-
treatment toxic action in evaluating mortality results.
The data on closed-system solution treatments obtained in the autumn
of 1941 are shown in table 1. Except as indicated, the solutions were pre-
pared by adding 1 part of methyl bromide to 2 parts of commercial ethyl alco-
hol in the mixing chamber and introducing this stock into the water in the
drum. Various quantities of water were used in solution preparation, This
may have introduced an error in the concentrations presumably obtained which
will require future adjustment. The percentage concentration of methyl
bromide is on a volumetric basis. This is used in preference to an expres-
sion of percentage by weight, inasmuch as it has been employed by other
workers in earlier publications. The percentages listed are based on assumed
complete solubility of the methyl bromide, whereas about 90 percent solubili-
ty is a more accurate figure. In any event, this is believed to be a relative-
ly constant amount. The records are exclusively for Japanese beetle larvae.
Table l.--Summary of closed-system collar treatments, 1941. All records are for
1/3-square-yard collars, with dosages as shown.
CH3Br :Dosage: Soil temperature :Solution:Number : Total :MortalityComments
concen-: per : :temper- : of :number of:
tration:collar:Surface: 2 in. :6 in.:ature :collars: grubs
Percent Gallons OF. OF. OF. OF. Percent
0.075 1 65 65 65 62 10 112 100.0
1 75 70 61 61 15 432 100.0
1 60 59 60 60 15 389 100.0 No alcohol
0.050 1 65 65 65 62 8 81 100.0
1 69 69 71 61 15 545 100.0
0 .0475 1 57 57 59 61 15 432 97.9 I/No alcohol
0.039 1 48 46 43 52 10 639 59.8
1 1/2 48 46 43 52 8 328 72.3
0.025 1 65 65 65 62 8 60 95.0
1 75 70 61 61 15 463 100.0
1 57 57 60 60 15 390 95.4 l/No alcohol
0.022 1 43 40 43 53 8 398 35.9
1 1/2 43 40 43 53 8 481 50.3
2 43 40 43 53 10 490 66.8
~- -- ----- ---------------------------- -- -- -- -- -- --
1/ Field mortality at examination. Judging from the behavior of the larvae,
mortality would have been somewhat greater if provision had been made for holding
grubs for subsequent examinations
The data shown are insufficient basis for the adoption of closed-
system solutions as a means for obtaining quarantine certification of nur-
sery stock to be moved out of the area under the quarantine against the Japan-
ese beetle. They demonstrate, however, that such solutions are effective in,
exceedingly low concentrations when used as described above. The three
records involving solutions of methyl bromide and water without alcohol
compare favorably with similar ones in which the methyl bromide-alcohol
stock was used.
With methyl bromide at 70 cents per pound, the cost of material for
treating with a 0.075-percent solution amounts to about 0.76 of a cent per
1/3-square-yard collar, with lower concentrations at proportionately lower
cost. On a larger scale, the cost of material for a 0.075-percent solution
amounts to about $37.25 per acre. This makes no allowance for labor and is
purely speculative, since no means for application on an acre basis have
(1) Chisholm, R. D., and Koblitsky, L. 1942. A chemical study of
the preparation and stability of aqueous methyl bromide solutions. Bur.
Ent. and Plant Quar., E-575, 8 pp.
(2) Livingstone, E. M., Easter, S. S., and Swank, G. R. 1940. Methyl
bromide in aqueous solution to control Pantomorus leucoloma and Pperi
nus. Jour. Econ. Ent. 33: 531-33.
(3) U. S. Dept. Agr. March 15, 1940. Administrative instructions
-- Modifying the restrictions of the white-fringed beetle quarantine by
authorizing treatment by methyl bromide solution of balled nursery stock
of specified thickness B. E. P. Q. 503 Revised, 2 pp.
UNIVERSITY OF FLORIDA
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