Factors affecting curly-top infectivity of the beet leafhopper,Eutettix tenellus

Abstract

does not appear. First page follows. Introduction A number of investigators have called attention to the fact that large numbers of beet leafhoppers, Eutettix tenellus (Baker), collected in the foothill breeding areas and on weeds in the cultivated areas, failed to transmit the curly-top virus to sugar beets. There have been occasional reports in the literature of large populations of leafhoppers in beet fields with a small amount of curly top developing during the season. Smith and Boncquet (23)3 tested fully 2,000 beet leafhoppers taken on Atriplex tularensis and Chenopodium album in the Tulare Lake region of the San Joaquin Valley upon several hundred sugar-beet plants without the production of curly top in a single instance. Boncquet and Hartung (1) report that 100 leafhoppers collected on species of Artemisia and Atriplex in the Tulare Lake region and confined singly in cages on beet seedlings failed to produce curly top. Hartung (5), in a detailed paper on the results of the same experiment, states that 87 insects were tested and that 7 per cent “probable” cases of curly top developed. These “probable” cases of curly top showed one or more slightly curled leaves, but no reliable symptoms of the disease, such as wartlike protuberances on the lower surface of the leaves.