(Montana State University - Bozeman, College of Agriculture, 2007) Meyer, Jack Robert; Chairperson, Graduate Committee: Barry J. Jacobsen.
Black Dot (Colletotrichum coccodes) is an important potato disease worldwide causing reported yield losses in the 10-30% range. It is involved in the early dying disease complex along with Verticillium dahliae or V. albo atrum, and root lesion nematodes. Besides early dying, black dot also causes silvery blemishes on the tuber surface that resemble those of silver scurf which results in reduced value in fresh markets. The purpose of this work was to evaluate North American cultivars for black dot tolerance and to evaluate fungicides for their efficacy in controlling this disease. To evaluate cultivar resistance, thirty-four commercial cultivars were evaluated in inoculated, greenhouse experiments for susceptibility to C. coccodes. Plant growth was then evaluated 60 days post inoculation. Inoculated plants were stunted and had reduced dry weight of 0% to 53.6% when compared to un-inoculated controls. Significant reductions in growth were observed for 25 of the 34 cultivars (P<0.05).
