Abstract
A technique involving a selective nutrient pectate medium and assay of air-dried potato stems with an Andersen sampler provided a means of quantifying V. dahliae in plant tissues. From both naturally and artificially inoculated potato cultivars, the recovery of V. dahliae from air-dried potato tissue was 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 2 potato clones (A66107-51 and A68113-4) as much more resistant to V. Dahliae than ''Russet Burbank'' plants with resistance showed an increase in yield. In contrast, ''Nampa'' and ''Butte'' were significantly more susceptible.

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