THE FUNGISTATIC AND FUNGICIDAL ACTIVITY OF VINCLOZOLIN AGAINST BOTRYTIS-CINEREA

The germination of Botrytis cinerea conidia in nutrient medium was com pletely inhibited by 20 mu M vinclozolin. Probits of the percentage in hibition of spore germination were linearly correlated with log vinclo zolin concentration indicating that vinclozolin acted as a single comp ound 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 contrar y, for germinated B. cinerea conidia growing in liquid medium, vincloz olin 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, r espectively. However, if vinclozolin was added to germinated spores in non-growing conditions, no significant reduction in cell viability wa s observed after 20 h of treatment. The results indicated that vincloz olin has a strong fungistatic activity, but is fungicidal only in acti vely growing cells, and that it causes no drastic alteration in the pe rmeability of the cytoplasmic membrane of resting conidial cells. The implications of these results for the chemical control of plant mycose s are briefly discussed.