STT VLJ946AR2 E-694
United States Department of Agriculture
Agricultural Research Administration Bureau of Entomology and Plant Quarantine
THE PREPARATION OF AQUEOUS SOLUTIONS OF ETHYLENE DIBROIDEETiLENE= DICHLORIDE I:IXTUTRES FOR FUJIGATION OF JAPANESE BEETLE LARVAE IN SOIL
By R. D. Chisholm and L. Koblitsky, Division of Insecticide Investigations, and A. C. Mason and L. W. Coles, Division of Fruit Insect Investigations
A mixture of ethylene dibromide and ethylene dichloride plus a
surface-active agent has recently been authorized for treating bare rooted wccody plats i, connection with the certification of nursery
stock under the Japanese beetle quarantine. The use of ethylene
dichloride solutions had previously been authorized for the certification of balled or potted plants (2), and a method for preparing
aqueous solutions has been described (1). The ethylene dicbloride
treatment involves the preparation of an emulsible product by
mixing the ingredients uniformly to make a clear solution,which is
diluted with water before use. The ethylene dibromide-ethylene
dichloride mixture is prepared in a similar way, the formula being
ethylene dibromide 16 percent, ethylene dichloride 81.5 percent,
and Tween 20 (a polyoxyalkylene derivative of sorbitan monolaurate)
2.5 percent (all by weight). It is diluted for use by vigorous
shaking with about 2 volumes of water to form a milky emulsion, and
then adding more water as desired, with stirring. In general a substantially clear solutio: will result if the stock mixture is used at a strength of about 0.3 fluid ounce or less per gallon of
water, At a higher strength a cloudy suspension may form, especially
at low temperatures.
Ethylene dibromide was found to be much more toxic to Japanese
beetle larvae than ethylene dichloride. Lower concentrations and
less time were required to kill all the larvae, particularly those
close to the surface of soil masses. A similar Indication of the
.relative toxicity of these fumigants was noted in 1930 by the late F. E. Baker (unpublished data). However, since ethylene dibromide
is a solid (melting point 500 F.) at temperatures at which some
nursery stock might be treated, it was added to ethylene dichloride
to form mixtures having suitable freezing points. In addition,
the vapors from this compound assist in the distribution of eth-1;.
dibro,,ide throughout soil masses.
Another formula, containing 62 percent of ethylene dibromide,
36 percent of ethylene dichloride, and 2 percent of Tween 20, was also tested, but the first formula was selected for authorization
UNIVERSITY OF FLORIDA
3 1262 09238 7579
under Japanese beetle quarantine regulations. The authorization provides for the use of the mixture as a dip at the rate of 10 ml. per gallon of water at temperatures above 500 F. under specified conditions.
(1) Chisholm, R. D., Koblitsky, L. Mason, A. C., and Coles, L. W.
1944. An aqueous solution of ethylene dichloride for fumigation
of Japanese beetle larvae. U. S. Bur. Ent. and Plant
Quar. E-626, 2 pp. (Processed.)
(2) U. S. Bureau of Entomology and Plant Quarantine.
1943. Treatments used as a basis of certification under Japanese beetle quarantine. U. S. Dept. Agr., B. E. P. Q.
529, 3 pp.