VIEW ARTICLE

Ecology and Epidemiology

Survival of Sclerotia and Conidia of Botrytis squamosa. L. A. Ellerbrock, Graduate Research Assistant, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, N. Y. 14853; J. W. Lorbeer, Professor, Department of Plant Pathology, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, N. Y. 14853. Phytopathology 67:219-225. Accepted for publication 11 August 1976. Copyright © 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-219.

Sclerotia of Botrytis squamosa survived for 21 months at rates of 7 and 66% when buried 3 and 15 cm, respectively, below the surface of an organic soil. Sclerotia placed on the soil surface in September 1971 were 96, 30, and 0% viable by 24 March, 21 May, and 25 July 1972, respectively. Myceliogenic germination rates for recovered sclerotia generally were higher than sporogenic rates. Large numbers of sclerotia of B. squamosa frequently were formed on blighted onion leaves before and after harvest. Formation was most prolific during wet periods in late August and September. Sclerotia also formed on onion bulb necks, seed stalks, and the inner leaf sheaths in the neck region of bulbs. Conidia of B. squamosa survived for short periods (usually less than 2 months) in natural soil under both controlled and field conditions. Higher temperatures reduced conidial survival and populations of conidia declined rapidly in soil that was alternately dried and remoistened. Mycelium of B. squamosa failed to survive in leaf debris under field conditions. Botrytis squamosa survived for 17 months in association with onion seeds but could not be recovered after 25 months. Rates of infestation of seed by B. squamosa were low; 6% was the maximum rate detected.