Survival of Colletotrichum coccodes in Infected Tomato Tissue and in Soil.

Studies were initiated in 1988 and 1991 to assess long-term survival ability of Colletotrichum coccodes. Sclerotia and infected tomato fruit skin tissue were enclosed in nylon pouches and placed on the soil surface (0 cm) or buried 10 and 20 cm deep in fields located in Geneva, New York. Over time, the greatest decline in recovery of C. coccodes from tomato skin and decrease in viability of sclerotia were from samples placed on the soil surface. In the 1988 study, after 8 years in the field, 0, 90, and 88% of the sclerotia were viable, and C. coccodes was isolated from 0, 54, and 86% of the tomato skin tissues at the 0-, 10-, and 20-cm soil depths, respectively. In the 1991 study, after 5 years in the field, C. coccodes was isolated from 22, 35, and 37% of the tomato skin tissues, and 55, 91, and 92% of the sclerotia were viable at the 0-, 10-, and 20-cm soil depths, respectively. It is apparent that lengthy crop rotations are required to significantly decrease viable inoculum of C. coccodes. In a separate study, C. coccodes overwintered in naturally infected tomato roots in commercial fields and was consistently isolated from roots in the fall and the following spring. Fields sampled in the fall yielded similar numbers of plants with infected roots the following spring.