VIEW ARTICLE

Disease Control and Pest Management

Biological Control of Crown Gall: Construction and Testing of New Biocontrol Agents. J. -S. Shim, Postgraduate student, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia 5064; S. K. Farrand(2), and A. Kerr(3). (2)Associate professor, Stritch School of Medicine, Loyola University of Chicago, Maywood, IL 60153, Present address: Department of Plant Pathology, University of Illinois at Urbana, Urbana 61801; (3)Professor, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia 5064. Phytopathology 77:463-466. Accepted for publication 11 September 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-463.

Transfer deficient (Tra^–) Tn5 insertion mutants of the agrocin 84 plasmid pAgK84 were transformed into two chromosomal backgrounds and the transformants tested as agents for biological control of crown gall on almonds and for colonization of almond seedling roots. Efficiency of root colonization and of biological control was influenced by the chromosomal background. Two Tra strains were as effective as the commercial Tra⁺ strain K84 in controlling crown gall. Strains of Agrobacterium radiobacter which contained a high copy number mutant of pAgK84 and overproduced agrocin 84 were no more effective, and in one case, significantly less effective in controlling crown gall than strains containing the normal copy number of pAgK84.