THE FUNGISTATIC AND FUNGICIDAL ACTIVITY OF VINCLOZOLIN AGAINST BOTRYTIS-CINEREA

The germination of Botrytis cinerea conidia in nutrient medium was completely inhibited by 20 mu M vinclozolin. Probits of the percentage inhibition of spore germination were linearly correlated with log vinclozolin concentration indicating that vinclozolin acted as a single compound with one mechanism of action. Treatment of resting (ungerminated) spores suspended in buffer with vindozolin concentrations as high as 750-1000 mu M resulted in no significant release of cellular potassium and inorganic phosphate or decrease in cell viability. On the contrary, for germinated B. cinerea conidia growing in liquid medium, vinclozolin showed a slow but marked fungicidal activity. After 3 and 20 h of treatment with 2 mu M vinclozolin, 63 and 4% of the cells survived, respectively. However, if vinclozolin was added to germinated spores in non-growing conditions, no significant reduction in cell viability was observed after 20 h of treatment. The results indicated that vinclozolin has a strong fungistatic activity, but is fungicidal only in actively growing cells, and that it causes no drastic alteration in the permeability of the cytoplasmic membrane of resting conidial cells. The implications of these results for the chemical control of plant mycoses are briefly discussed.