Potential fungicidal activity of 3-(substituted oxy)-5-methylisoxazoles

The structure of the commercial fungicide hymexazol, 3-hydroxy-5-methylisoxazol, was transformed to acyloxy, 3-alkoxy, alkylcarbamoyloxy and acylamino derivatives, and their antifungal activities or disease control activities were examined. The 3-acyloxy derivatives were much more active than the other derivatives, and some of the 3-acyloxy derivatives exhibited antifungal activities or disease control activities against a wide range of pathogens, such as Pyrenophora graminea, Alternaria alternata, Cercospora beticola, Rhynchosporium secalis, Septoria tritici, Microdochium nivale, Rhizoctonia solani, Puccinia recondita, and Blumeria graminis. Among them, 5-methyl-3-isoxazolyl (alpha)-naphthoate and (o)-toluate and 2,2-dichloro-1,3,3-trimethylcyclopropanecarboxylate completely inhibited the mycelial growth of Rhizoctonia solani and M. nivale at 25 mg/L, respectively. (C) Pesticide Science Society of Japan