There are numerous important potato diseases that are annual production concerns for growers in Michigan. This study included three projects. The first project evaluated commercial cultivars and advanced breeding lines (ABL) with foliar resistance to late blight via tuber tests, and integrated disease management with foliar resistant varieties/ABLs in combination with fungicide seed treatments against four of genotypes of P. infestans. Commercial cultivars and ABLs showed differential responses to genotypes of P. infestans based on both experiments. Overall, ABLs and commercial cultivars in combination with seed treatments performed better based on plant stand compared to inoculated non-treated controls. A second project evaluated conventional and quantitative PCR primers for detection of Pectobacterium and Dickeya spp. to monitor the presence and spread of these bacteria in the field and in seed-lots for certification. In two consecutive years samples from the field had both Dickeya and Pectobacterium spp. Whereas, tubers from seed-lots from Michigan seed production did not test positive for Dickeya spp. and overall relatively low levels of Pectobacterium spp. within acceptable tolerance. Three conventional PCR primers were reliable and were able to differentiate Pectobacterium down to species. Finally, a third project characterized Streptomyces spp. recovered from potato and turnip phenotypically based on virulence, pathogenicity, and morphologically, and determined the diversity and phylogenetic relationships among species. This study identified morphological, molecular and phylogenetically differences among Streptomyces spp. isolated from turnip and potato.
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