Canadian Forest Service Publications
Discharge and germination of Eutypella parasitica ascospores. 1971. Lachance, D. Canadian Journal of Botany 49(7): 1111-1118.
Issued by: Laurentian Forestry Centre
Catalog ID: 15422
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Perithecia of Eutypella parasitica on cankered sugar maple in natural stands, discharged ascospores only when rainfall occurred. However, there was no relationship between amount of rainfall and intensity of spore discharge. High relative humidity alone did not induce spore ejection, but wetting of perithecia did. Variations in summer temperature appeared not to influence spore release. In laboratory studies, spore discharge from wetted clusters of perithecia on excised pieces of bark kept in moist chambers, was heavy at 20°C, light at 12°C, and nil at 4°C. Although near-freezing temperature inhibited ascospore discharge, exposure to warm temperature of previously frozen perithecia quickly induced release of viable ascospores. Ascospores germinated readily in water or on common agar media. Germination was rapid at 20°C, slow at 12°C, and nil at 4°C. Ascospores remained viable for several months when stored dry at 4°C; up to 13% still germinated after 20 months of storage. Ascospores stored dry at 20°C germinated poorly after 5 weeks.