Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

The occurrence of highly virulent strains of the beet curly top virus in California.

Abstract

Tests on isolates collected during 1974 and 1975 from field beets and weeds in the San Joaquin Valley indicated that they have a higher degree of virulence than those found in the 1950s and 1960s. Strs. of increasing virulence are apparently evolving both in the foothill breeding grounds and in the agricultural areas. The hypothesis that severe isolates tend to be self-eliminating in the breeding grounds does not seem valid.<new para>ADDITIONAL ABSTRACT:<new para>Strains of beet curly top virus, transmitted by Circulifer tenellus, have been isolated in the San Joaquin Valley, California, which are more virulent than those found in the previous two decades.<new para>ADDITIONAL ABSTRACT:<new para>The following weed species in the foothills of the San Joaquin Valley were found to be affected by beet curly top virus: Capsella bursa-pastoris, Sisymbrium irio, Bassia hyssopifolia, Salsola iberica and S. paulsenii. Tests of isolates from affected weeds showed them to be more virulent than those found in the 1950s and 1960s; strains of increasing virulence appear to be evolving in these breeding grounds and in the agricultural areas.