Ferimzone (proposed common name), (Z)-2'-methylacetophenone 4, 6-dimethyl-2-pyrimidi. nylhydrazone, is a new fungicide with curative activity, which is effective against rice blast, leaf brown spot, stem-rot, and sheath blight by foliar treatment.The possibility of replacement of the hydrazone group in the ferimzone molecule by a pyrazole ring was investigated.As a result of the present study, the structure was remarkably modified by the replacement with alkyl-substituted pyrazoles which apparently resembled the hydrazone moiety and satisfied the prerequisites to the activity.A strategy for synthesizing pyrazole isosters and their fungicidal activities are described.