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Disease Control and Pest Management

Protection of Pisum sativum from Fusarium solani f. sp. pisi by Inhibition of Cutinase with Organophosphorus Pesticides. W. Köller, Research associate, Institute of Biological Chemistry, Washington State University, Pullman 99164; C. R. Allan(2), and P. E. Kolattukudy(3). (2)(3)Research associate, and professor of biochemistry, respectively, Institute of Biological Chemistry, Washington State University, Pullman 99164. Phytopathology 72:1425-1430. Accepted for publication 31 March 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1425.

The phosphoorganic insecticides Paraoxon, O, O-dimethyl- O-(2,4,5-trichlorophenyl) phosphate, Fospirate, O, O-diethyl-O-(3,5,6-trichloro-2-pyridyl)phosphate, Parathion, Dowco 214, and Chloropyrifos, and the phosphoorganic fungicides Hinosan, Inezin, Conen, and Kitazin P were shown to be powerful cutinase inhibitors. The I50 values ranged from about 10–3 to 10–9 M. All pesticides prevented infection of Pisum sativum by Fusarium solani f. sp. pisi under controlled conditions of a pea stem bioassay on intact cuticles only. Infection was not prevented on wounded pea stems. The effective pesticide concentrations reflected, to a certain degree, the corresponding I50 values for cutinase inhibition. No inhibition of mycelial growth was observed at these pesticide concentrations. These results suggest that the pesticides prevented penetration, and thus infection, by inhibiting cutinase released by the fungal infection structure.

Additional keywords: antipenetrants, cutin, cuticle.