Studies on the germination of sclerotia of Sclerotinia sclerotiorum

Abstract

Sclerotial germination of 33 isolates of Sclerotinia sclerotio-rum, which were collected from different regions and crops, was compared at 10†C in a climate chamber. Germination of S. sclerotiorum, measured as the number of sclerotia producing stipes and apothecia, was the predominant mode that was affected significantly by isolate. Isolates which originated from a warmer area generally germinated more quickly. The culture media affected the viability of sclerotia of isolates M01 and MZ. Sclerotia germinated on different substrates such as standard gardener`s soil, sand and vermiculite, but did not germinate well when the sclerotia had developed on nutrient-rich or nutrient-poor medium. The optimum medium for sclerotial development was wheat grain. Sclerotia produced on wheat grain were well-suited for studies on germination of sclerotia and formation of apothecia. The production of apothecia was optimal at a temperature of 10†C and an illumination of 500 lux, and after an incubation period of 2 to 3 months. One apothecium produced over 1 million ascospores and survived over 15 days in the climate chamber.