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Physiology and Biochemistry

Fungitoxicity of Derivatives of o-Phenylphenol. Joseph W. Eckert, Professor of plant pathology, Department of Plant Pathology, University of California, Riverside 92521; Oladele F. Esuruoso(2), and June Carey(3). (2)Professor of plant pathology, Department of Agricultural Biology, University of Ibadan, Nigeria; (3)Staff research associate, Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 69:1092-1095. Accepted for publication 3 April 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-1092.

Several isolates of Diplodia natalensis and Penicillium digitatum were inhibited strongly by o-phenylphenol and its esters, 2-biphenylyl acetate and 2-biphenylyl propionate. o-Phenylanisole was moderately inhibitory to D. natalensis but was less active against P. digitatum. More than 80% of the 2-biphenylyl propionate added to cultures of D. natalensis and P. digitatum was hydrolyzed to o-phenylphenol within 2 hr. Biphenylyl acetate was degraded by D. natalensis at a similar rate but was significantly more resistant to attack by P. digitatum. Fungitoxicity of the esters of o-phenylphenol to both fungi may result from enzymatic hydrolysis of the esters and subsequent accumulation of inhibitory levels of o-phenylphenol in the cultures. Neither fungus degraded o-phenylphenol during the 24-hr incubation. D. natalensis demethylated 10% of the o-phenylanisole added to the culture in 24 hr, but P. digitatum converted only 1% of the anisole to o-phenylphenol during the same period. The toxicity of o-phenylanisole to D. natalensis was greater then could be accounted for by the accumulation of o-phenyphenol in the hyphae. Hyphae of D. natalensis bound significantly more o-phenylanisole than P. digitatum, and this factor may be responsible for the selective fungitoxicity of this compound.

Additional keywords: phenol ester, phenol ether.