A comparison of the mechanisms of action of vinclozolin,procymidone, iprodione and prochloraz against Botrytis cinerea

The mechanisms of action against Botrytis cinerea of the dicarboximide fungicides vinclozolin ( I ), procyrnidone ( II ), iprodione ( III ) and the less closely related compound prochloraza ( IV ) have been compared. They all inhibited mycelial growth much more than spore germination. None of the compounds affected respiration, membrane permeability or RNA production but III inhibited DNA synthesis and IV inhibited protein synthesis. Although chitin biosynthesis was inhibited by all the fungicides it was barely affected at the ED₅₀ concentrations (the concentration required to reduce the growth or germination of the test species by 50%) and is thus unlikely to be the primary target. The fungicides altered fungal lipid composition. I and II inhibited triglyceride production but III had no effect on it; III and IV reduced sterol biosynthesis. No common primary mode of action was found.