Jim I Mcloughlin

Pyrazole carboxanilide fungicides.

Novel N-[2-(cyclic alkyl)phenyl]pyrazole-4-carboxamides useful as fungicides, methods of using said compounds, and fungicidal compositions containing them.Abstract A series of carboxin-like compounds, the N -methylpyrazole carboxanilides and their mono- and dimethyl derivatives have been assayed as inhibitors of succinate dehydrogenase enzyme complexes (SDCs) isolated from Ustilago maydis, Rhizoctonia solani, Gaeumanomyces graminis , and Fusarium oxysporum . The pattern of inhibitory activity within the series was broadly similar for each of the fungi although minor differences indicated some structural variation between the enzyme complexes. There was a general correlation between inhibition of the SDCs isolated from R. solani and G. graminis and inhibition of mycelial growth of these same organisms which was consistent with the primary mode of action of these compounds being interference with mitochondrial electron transport. No such correlation was evident with F. oxysporum , where some of the compounds showed activity against the SDC but none had any effect on fungal growth. This suggests that if SDC inhibitory activity is the primary determinant of the anti-fungal activity of these compounds it does not necessarily determine their anti-fungal specificity: some possible explanations are offered.