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Show Entomologists Find Early Season Alfalfa Weevil Control Gets Results By George F. Knowlton, Extension Entomologist, Utah State Agricultural College Control of the alfalfa weevil is desirable every year in j most parts of Utah. Owing to the very rapid plant growth I which occurred after the spring rains of 1953 the crop grew very well. However, the alfalfa weevil has commonly common-ly caused great damage in most areas of Utah where early spring control had been neglected. The new early spring insecticide "stubble" treatments have resulted in effective adult weevil control. A high-quality, high-quality, high-yield alfalfa crop was produced rather uni-i uni-i formly over the early-spring treated areas of Utah during 1951-1953. My efforts to determine the value of this weevil control treatment to the growers of forage for-age hay and alfalfa seed crops Vrir IawI in the . nnnplncinn Itint this early spring treatment has I meant a cash benefit of $f)00,000 to $1,000,000 to the farmers and ranchers of Utah. This benefit was secured solely as a result of this early spring chemical spray application. In some years, besides be-sides controlling alfalfa weevils, it also has helped control the army cutworms in some areas. The alfalfa weevil early season sea-son program has been developed largely by U S D A entomologist entomolo-gist F. V. Lieberman and his associates as-sociates at the Utah Agricultural Experiment Station, legume seed research laboratory. Entomologists Entomolo-gists working in Montana, Wyoming Wyo-ming and in other western states also have conducted research on the program. This alfalfa pest can be controlled economically! bv destrovinc the overwintered adult weevils, research has found. Control, however, must be accomplished before the female lays many eggs. Eggs laid before be-fore control is applied will hatch and become worms to feed on alfalfa foliage during June and early July. For six yeais now, recommended spray applications, appli-cations, put on when early spring growth alfalfa reached a height of one to two inches, has destroyed de-stroyed a very high percentage of adult alfalfa weevils which had survived through the winter in the alfalfa fields. This early control has largely prevented gg laying. When this treatment has been properly timed, so few alfalfa alfal-fa weevil larvae ordinarily have been present in the fields that economic injury rarely occurred. Research during the past several years has shown that dieldrin, applied at the rate of 1 pints of the 18 emulsifiable concentrate concen-trate per acre, and 25 emulsifiable emulsi-fiable heptachlor at one pint per acre, also has given excellent control when sprayed on the fields before alfalfa exceeded two inches in early spring growth. In 1953 great amounts of heptachlor and dieldrin, as well as some chlordanc. were sprayed or, alfalfa stubble in very early spring. The result was excellent weevil control in rract'cal'V a" cases. Control chemicals should he adequate in supply for all Utah needs in 1954. I |