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Poster: Diseases of Plants: Disease Detection & Diagnosis


BioPCR: An improved method for detection of Colletotrichum acutatum in asymptomatic strawberry nursery plants
P. SUDARSHANA (1), K. Mani (1), P. Randhawa (1), T. Walters (2) (1) California Seed and Plant Labs, U.S.A.; (2) Walters Ag Research, U.S.A.

Colletotrichum acutatum infections in strawberry nurseries often stay symptomless. Infected plants usually collapse upon transplanting in grower fields resulting in economic losses to the growers. A routine method to detect C. acutatum in asymptomatic plants is to culture root and crown tissue on semi-selective agar media such as TPDA and BR and confirm identification by microscopic observations of spore morphology and PCR. In our experience, the culture method often fails to detect C. acutatum when non-target fungi such as ?Trichoderma sp., ?Alternaria sp. and Aspergillus sp. are present in a sample. The rapid growth of non-target fungi mask the pathogen in culture. To overcome this problem, we investigated BioPCR as an alternative method to detect infections in asymptomatic tissue. In BioPCR, tissue was cultured for four days on agar media to enrich C. acutatum in the plant tissue. After 4 days, tissue was removed from the culture plates and tested by PCR using primers specific for C. acutatum (1). Culture plates were still available for reading. During 2015, we analyzed 106 commercial samples from strawberry nurseries in California by culture and BioPCR method. BioPCR detected C. acutatum in 83% plants compared to 42% by culture method. We conclude that BioPCR method is superior to culture method and can be used to assay strawberry nursery plants for detection of C. acutatum in asymptomatic plants.