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Disease Control and Pest Management

Biological Control of Crown Gall with Fungal and Bacterial Antagonists. D. A. Cooksey, Graduate research assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; L. W. Moore, associate professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 70:506-509. Accepted for publication 11 November 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-506.

Pathogenic Agrobacterium strains were inhibited in vitro by 35 different fungi and bacteria that were isolated from nursery soils in Oregon and Washington. Seven of the 35 antagonists inhibited six A. tumefaciens strains in vitro, and also prevented infection of tomato seedlings in the greenhouse. In field tests, isolates of Penicillium, Aspergillus, Bacillus, Pseudomonas, and A. radiobacter reduced the incidence of galling on mazzard cherry seedlings by some of the pathogens tested, but none was more effective than A. radiobacter strain 84. With some antagonists, greater reduction in galling was observed when cherry seedlings were inoculated with pathogen mixtures 24 hr after inoculation with antagonists. One Penicillium antagonist reduced the incidence of infection to a level below that of the wounded controls when used against some pathogenic strains.