2008 Annual Report
The influence of tuber and soil-borne inocula of Colletotrichum coccodes on black dot severity was studied in four consecutive years in the greenhouse. Potato tubers were either inoculated or not inoculated with a conidial suspension of C. coccodes, and were grown in soil infested or not infested with sclerotia. Sclerotial densities on roots and crowns, and sclerotial height on stem were greater (P<0.05) on potatoes grown in infested soil or from infected tubers in infested soil than on potatoes grown from infected tubers, or from non-inoculated control plants in three of four years. More (P<0.05) progeny tubers were infected with C. coccodes when plants were grown from infected tubers in non-infested soil than when plants were grown in infested soil in only one of three years. Total yield in two of four trials was significantly (P<0.05) or notably (P=0.059) lower when plants were grown in infested soil from infected or non-infected tubers than when plants were grown in non-infested soil from infected tubers. The influence of soil-borne inoculum concentrations of C. coccodes on the severity of black dot was studied in two trials in the greenhouse. The soil was infested with 0, 0.5, 1.7, 5, and 8.3 grams of inoculum per 1-liter. The study supported the hypothesis that soil-borne inoculum of C. coccodes has a higher disease causing potential than tuber-borne inoculum. The study also indicated that soil-borne inoculum of C. coccodes has a low disease threshold. A small level of inoculum in the soil is sufficient to cause high levels of damage. This research falls within NP 301 Component 3: Genetic Improvement of Crops. 3c: Germplasm Enhancement/Release of Improved Genetic Resources.
Oversight of the Specific Cooperative Agreement was carried out by telephone conversations, in-person meetings, and sharing of data by email between the ADODOR and Washington State University's lead researcher.