Aphid Control Trials on Sugar Beets and Virus Yellows Disease in Kern County, California

Abstract

The economic feasibility of the use of systemic pesticides (either demeton or Di-Syston® ( O-O -diethyl S- 2(ethylthio)ethyl phosphorodithioate) for the suppression of aphid vectors of the sugar beet yellows viruses was indicated from the results obtained on replicated plots conducted in Kern County. California, during the spring of 1960. In terms of tons of beets per acre, a preplant application of Di-Syston granules at a rate of approximately l pounds of actual toxicant per acre was found to be better than no treatment, but inferior to any other treatment schedule whether it involved one or two treatments. The best treatment combination used was a preplant treatment with Di-Syston granules followed by an application of a demeton spray (applied at a rate of 8 ounces of actual toxicant per acre in 44 gallons of water) when sampling indicated that the number of infested plants approached 50%. Under conditions of a multi-treatment test, however, increased yields were also found with a single treatment schedule of either a demeton spray or a topical application or a side dressing of Di-Syston granules (at a rate of approximately 1 pound actual toxicant per acre). Because of the inherent difficulty in predicting the development of aphid populations and the relative slowness with which a side dressing becomes effective, it would probably offer the least reliability of the various treatment schedules tried, with the exception of the single preplant treatment.