Disease Note.

Basil as a Host of Sclerotinia minor. S. T. Koike, University of California Cooperative Extension, Salinas 93901. R. D. O’Brien, United Organic Growers, Inc., P.O. Box 67, Salinas 93902. Plant Dis. 79:859. Accepted for publication 16 June 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0859D.

In 1994, in Santa Cruz County, Calif., commercial organic plantings of basil (Ocimum basilicum L.) exhibited wilting and collapsing just prior to harvest. Crowns and lower stems were necrotic and white mycelium was observed on affected parts. Sclerotinia minor Jagger was consistently isolated from symptomatic plants. Pathogenicity tests were done using 6-week-old basil (cv. Genovese) and 4-week-old lettuce (Lactuca sativa L. cv. Alpha) transplants potted into sterilized sand. Sclerotia of the basil isolate of 5. minor were produced on sterilized potato pieces (1) and inserted into the sand at a depth of 0.5 cm and 0.5 cm from test plants. Control basil and lettuce plants did not receive sclerotia. All plants were incubated in a greenhouse at 21 to 23°C. After 3 weeks, inoculated basil and lettuce plants wilted and collapsed and S. minor was reisolated from necrotic crown and stem tissues. Uninoculated plants remained asymptomatic. The experiment was repeated once and results were similar to the first inoculations. This is the first report of basil as a host of S. minor.