Biological activity and disease controlling efficacy of penthiopyrad

Various carboxamide derivatives were synthesized, and the fungicidal activity was evaluated by both in vitro and in vivo experiments to find out the best compound for a fungicide. Penthiopyrad is unique in its wide fungicidal spectrum. The introduction of a thiophene ring with hydrophobic branched alkyl groups brought broad-spectrum fungicidal activity leading to the discovery of penthiopyrad, N-[2-(1,3-dimethylbutyl)-3-thienyl]-1-methyl-3-(trifluoromethyl)-1H-pyrazole-4-carboxamide. Of the carboxamide fungicides, carboxin is particularly effective for controlling the diseases caused by basidiomycetous fungi, including smut and bunt of cereals, but it is not as effective against others that are easily controlled by boscalid, which is not so effective against basidiomycetes pathogens. Penthiopyrad covers the effect gap between carboxin and boscalid. In this report, we have focused on the biological properties revealed in laboratory tests and small pot tests in the greenhouse.