Detection and Spread of Potato Virus S. E. M. Khalil, Department of Plant Pathology, University of California, Davis 95616. T. A. Shalla, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 66:368-371. Accepted for publication 22 July 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-368.

Enzyme-linked immunosorbent assay (ELISA) detected potato virus S in purified virus preparations at concentrations as low as 100 ng/ml and in extracts from naturally infected potato plants. The best stage of plant development for virus detection was at or before flowering with samples from middle leaves of the plant. Potato virus S could be detected in composite samples of leaves from 20 to 30 plants. By ELISA, spread by leaf contact was shown in greenhouse and field conditions. In plots initially containing 10% infected plants, the number of infected plants increased approximately twofold in one season.

Keyword(s): epidemiology.