VIEW ARTICLE

Disease Control and Pest Management

Effects of Metalaxyl on Phytophthora cactorum and Collar Rot of Apple. M. A. Ellis, Assistant professor, Department of Plant Pathology, Ohio State University, Columbus 43210; G. G. Grove(2), and D. C. Ferree(3). (2)Graduate research associate, Department of Plant Pathology, Ohio State University, Columbus 43210; (3)Professor, Department of Horticulture, Ohio Agricultural Research and Development Center (OARDC), Wooster 44691. Phytopathology 72:1431-1434. Accepted for publication 7 April 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1431.

Metalaxyl at low concentrations was highly inhibitory to mycelial growth, sporangia production, and zoospore germination of Phytophthora cactorum. Following soil drenches in the greenhouse, metalaxyl was taken up by apple roots and translocated upward in sufficient quantity to prevent growth of P. cactorum and Pythium ultimum on sections of wood taken from 15 cm above the soil line. Soil drenches prevented infection of apple trees inoculated with P. cactorum in the greenhouse. Soil drenches around naturally infected trees in the field resulted in remission of typical collar rot symptoms. The use of metalaxyl as a soil drench may provide an effective new method of controlling apple collar rot.