Disease Note

First Report of Lettuce Drop Caused by Sclerotinia minor in Quebec, Canada. R. D. Reeleder, Department of Plant Science, Macdonald College of McGill University, Ste. Anne de Bellevue, Que., Canada H9X 1C0. F. Charbonneau, Department of Plant Science, Macdonald College of McGill University, Ste. Anne de Bellevue, Que., Canada H9X 1C0. Plant Dis. 70:603. Accepted for publication 31 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-603d.

Disease surveys were conducted in muck soil lettuce (Lactuca sativa L.) fields in southern Quebec during 1984 and 1985. The mean incidence of lettuce drop was 0.1% (four fields, incidence range 0–0.3%) in 1984 and 0.7% (25 fields, incidence range 0–9.5%) in 1985. In 1984, Sclerotinia sclerotiorum (Lib.) de Bary was the only species causing drop. In 1985, S. sclerotiorum was observed in 22 fields (average incidence 0.3%) and S. minor Jagger was observed in three fields (average incidence 3.7%). In one of the latter fields, the incidence of lettuce drop was 9.5%, higher than that of all other fields examined. This is the first report of S. minor attacking lettuce in Quebec, and spread of this species to other lettuce fields in that province could have serious implications for producers.