Biological Control of Crown Gall in South Africa by Agrobacterium radiobacter Strain K84. H. J. Du Plessis, Fruit and Fruit Technology Research Institute, Private Bag X5013, Stellenbosch 7600. M. J. Hattingh, Department of Plant Pathology, and H.J.J. Van Vuuren, Department of Microbiology and Virology, University of Stellenbosch, Stellenbosch 7600, South Africa. Plant Dis. 69:302-305. Accepted for publication 1 September 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-302.

In a study on the ability of Agrobacterium radiobacter strain K84 to control 82 pathogenic strains of Agrobacterium, 36% of 69 South African strains were highly sensitive and 15%, moderately sensitive to agrocin 84 in vitro. Highly sensitive and certain insensitive strains were effectively controlled in vivo after introduction of suspensions at different pathogen:strain K84 ratios into stems of tomato seedlings. Moderately sensitive strains were not effectively controlled in vivo. Studies on tomato seedlings and roots of five other host plant species confirmed that other mechanisms such as physical blockage of infection sites are also involved in biological control.

Keyword(s): Agrobacterium tumefaciens.