VIEW ARTICLE

Disease Control and Pest Management

Potential for Biological Control of Phytophthora Root and Crown Rots of Apple by Trichoderma and Gliocladium spp.. V. L. Smith, Postdoctoral associate, Departments of Plant Pathology and Horticultural Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456, Present address: Department of Plant Pathology and Ecology, Connecticut Agricultural Experiment Station, P. O. Box 1106, New Haven 06504; W. F. Wilcox, and G. E. Harman. Associate professor, and professor, Departments of Plant Pathology and Horticultural Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456. Phytopathology 80:880-885. Accepted for publication 9 March 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-880.

A system was developed to identify isolates of Trichoderma and Gliocladium with potential for biocontrol of P. cactorum. Seedlings from open-pollinated McIntosh apples were grown in potting mix infested with both Phytophthora cactorum and candidate biocontrol fungi (Trichoderma and Gliocladium spp.). After 14 days of growth and a 72-hr flooding interval, significant reductions in root damage and increases in plant weight, compared with seedlings exposed to P. cactorum alone, were observed with some isolates of biocontrol candidates. Presence of both the pathogen and biocontrol fungi in the potting mix significantly influenced plant weight and the incidence of hypocotyl infection, and chi-square analysis indicated a lack of independence between qualitative root damage ratings and the presence of biocontrol agents. In the absence of P. cactorum, growth of apple seedlings was significantly increased by the presence of some isolates of biocontrol fungi. The system developed will aid in the identification of isolates of Trichoderma and Gliocladium spp. with potential for biocontrol of P. cactorum.