The effect of three fungicides, specific for the control of rice blast disease, on the growth and melanin biosynthesis by Pyricularia oryzae Cav

Tricyclazole (EL 291) and 2 recently developed compounds PP 389 and pyroquilon (CGA 49104) were essentially non-toxic to the fungus in vitro at up to 50 mu g/ml but each selectively inhibited melanin biosynthesis at much lower concs. This inhibition resulted in the accumulation of 2-hydroxyjuglone and flaviolin.