Longevity of Normal and Abnormal Sclerotia of Sclerotinia sclerotiorum . H. C. HUANG, Research Centre, Agriculture and Agri-Food Canada, P.O. Box 3000 Main, Lethbridge, Alberta, Canada T1J 4B1. G. C. KOZUB, Research Centre, Agriculture and Agri-Food Canada, P.O. Box 3000 Main, Lethbridge, Alberta, Canada T1J 4B1. Plant Dis. 78:1164-1166. Accepted for publication 10 September 1994. Copyright 1994 Department of Agriculture and Agri-Food, Government of Canada. DOI: 10.1094/PD-78-1164.

Morphologically abnormal and structurally deformed sclerotia of Sclerotinia sclerotiorum are common in samples of sclerotia collected from diseased (head rot) sunflowers grown in Manitoba and Alberta. Sclerotia collected from infected sunflowers were stored in paper bags at room temperature (20 ± 2 C) (four Manitoba samples) or at various temperatures (two Alberta samples). Subsamples of sclerotia were sorted and classified as normal, slightly abnormal, or grossly abnormal on the basis of surface characteristics and the degree of discoloration of medullary tissue and then were tested for viability. Viability of sclerotia decreased with degree of abnormality, duration of storage, and storage temperature. The difference in rate of viability decrease between normal and abnormal sclerotia was greater at above-freezing temperatures than at below-freezing temperatures. When sclerotia were air-dried and stored at 20°C for 62 mo, viability was 15% for grossly abnormal sclerotia and 65% for normal sclerotia.

Keyword(s): survival