VIEW ARTICLE

Techniques

A Sensitive Method for Quantifying Verticillium dahliae Colonization in Plant Tissue and Evaluating Resistance Among Potato Genotypes. J. R. Davis, Professor, Department of Plant and Soil Sciences, University of Idaho Research and Extension Center, Aberdeen, ID 83210; J. J. Pavek(2), and D. L. Corsini(3). (2)Geneticist, USDA-ARS, University of Idaho Research and Extension Center, Aberdeen, ID 83210; (3)Plant pathologist, USDA-ARS, University of Idaho Research and Extension Center, Aberdeen, ID 83210. Phytopathology 73:1009-1014. Accepted for publication 9 February 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1009.

A technique involving a selective nutrient pectate medium and assay of air-dried potato stems with an Andersen sampler provided a means of quantifying Verticillium dahliae in plant tissues. From both naturally and artificially inoculated potato cultivars, the recovery of V. dahliae from air-dried potato tissue was found to be highly correlated with foliar wilt symptoms. A straight-line relationship for V. dahliae recovery with time was demonstrated by this method, and isolations from fresh stem tissue were highly correlated with assays from air-dried tissue. Inoculum levels in soil were similarly correlated with the rate of V. dahliae colonization in potato-stem tissue. Greenhouse and field studies with this procedure have consistently indicated two potato clones (A66107-51 and A68113-4) to be much more resistant to V. dahliae than the Russet Burbank cultivar; plants with resistance showed an increase in yield. In contrast, Nampa and Butte cultivars were found to be significantly more susceptible.