Light-induced synchronous conidiation in the fungus Botrytis cinerea

Botrytis cinerea Pers. ex Fr. in stationary liquid cultures conidiated asynchronously in darkness after 4 days' growth. Synchronous conidiation was induced by irradiating dark-grown cultures with near-ultraviolet light for 12 h. The number of conidia increased very rapidly 10 h after the end of the photo-induction period, and conidiation was completed by the 14th hour. Filter paper cultures of the fungus also showed synchronous conidiation upon irradiation with near-ultraviolet light, but the rapid increase in the number of conidia took place 2 h earlier, conidiation being completed by the 12th hour. Cultures irradiated with blue light, however, produced sterile mycelia and showed complete suppression of conidiation.