Repeated germination of sclerotia of Botrytis convoluta to produce successive crops of conidia

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Abstract
Six successive crops of mature conidia were produced at 5 °C by sclerotia of Botrytis convoluta when each sporulation was preceded by a 24-h exposure to near-ultraviolet (n.uv.) radiation. Conidial production during these sporulations was greatest during the second sporulation while the largest number of conidia produced per unit of weight lost during the sporulations occurred during the third sporulation. Sporulation began to decline after the dry weight of the sclerotia had fallen to 32% of its initial level.The improved sporulation that occurred during the second sporulation was more marked at 10 °C than at any other temperature tested. It resulted in a shift in the optimum temperature for sporulation from 5 °C during the first sporulation to 10 °C during the second sporulation.At 5 °C, sclerotia were able to produce at least four crops of conidia after only a single, initial 24-h exposure to n.uv. radiation. The total number of spores produced during these sporulations was 11% below that of sclerotia exposed to n.uv. radiation before each of the four sporulations. When sclerotia were placed at 25 °C for the first sporulation, however, they did not sporulate again at either 5 °C or 25 °C without additional exposure to n.uv. radiation.When conidia and conidiophores of one sporulation were left intact on the sclerotia, they did not produce further crops of conidia under otherwise favorable conditions. The suppression of repeated sporulation was lifted by the removal of the conidia. Removal of the conidiophores as well as the conidia did not further influence the number of conidia produced during the subsequent resporulation.

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