Induction of myceliogenic germination of sclerotia of <em>Sclerotinia sclerotiorum</em> by exposure to sub-freezing temperatures.

When sclerotia of a Canadian isolate of Sclerotinia sclerotiorum were exposed to temperatures of -10 or -20&#176;C for 4 weeks, their germination behaviour changed from carposenic to myceliogenic type. Mycelial growth from sclerotia exposed to -20&#176;C was more vigorous than that from sclerotia exposed to -10&#176;C. The mode of germination in sclerotia treated with above-freezing temperatures of 0.5, 10, 15, 25 or 30&#176;C did not change: they retained the capacity for carpogenic germination. The possible epidemiological impact of this low-temperature induction or myceliogenic germination on lee development of sclerotinia wilt of sunflower seedlings in western Canada is discussed. [ABSTRACT FROM AUTHOR]