Abstract
Inhibition of melanin production was observed in Gaeumannomyces isolates treated with DHN-melanin inhibiting compounds (tricyclazole, pyroquilon, fthalide and chlobenthiazone) but not with DOPA-melanin inhibiting compounds (tropolone, kojic acid, 2-mercaptobenzimidazole and diethyldithiocarbamate). This indicates that the melanin associated with cell walls of G. graminis and G. incrustans is DHN-melanin. Depending on the compound, consistent inhibition of melanin was observed at levels that were not inhibitory to fungal growth. In vitro pathogenicity to wheat by these isolates was not affected by the DHN-melanin compounds.