First Report of Basal Drop and White Mold on Lettuce, Broccoli, and Mustard Caused by Sclerotinia sclerotiorum in Tennessee, U.S.A.

Sclerotinia sclerotiorum causes basal drop and white mold diseases on a wide range of vegetable crops, resulting in significant economic loss (Purdy 1979). Diseased plants of various vegetables with black irregular to cylindrical sclerotia were observed in high tunnels of an organic farm near Knoxville, TN in February of 2016 and 2017. Leafy mustard (Brassica juncea ‘Purple Osaka’) had necrotic leaves and stems, with black sclerotia inside stems. Chinese broccoli (Brassica oleracea var. alboglabra ‘Te You’) had water soaked lesions on stems and leaves with white mycelium and black sclerotia. Two kinds of lettuce (Lactuca sativa); butterhead ‘Mirlo’ and red leaf ‘Cherokee’, had symptoms of lettuce drop, i.e., water soaked leaves and crown with white mycelial mats and black sclerotia. Infected plants (1 to 3-cm pieces) and sclerotia, collected in both years, were surface sterilized in 10% commercial bleach for 1 min, followed by 1 min in 10% ethanol. Samples were plated on potato dextrose agar amended with ...