Anastomosis Groups and Pathogenicity of Rhizoctonia solani Isolates from Brazil. H. A. Bolkan, Associate Professor, Department of Biological Sciences, University of Brasilia, Brasilia, DF, 70.910, Brazil. Wilma R. C. Ribeiro, Graduate Research Associate, Department of Biological Sciences, University of Brasilia, Brasilia, DF, 70.910, Brazil. Plant Dis. 69:599-601. Accepted for publication 17 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-599.

Anastomosis groups (AG) of 130 Rhizoctonia solani isolates obtained from 31 plant species found in 11 states of Brazil were determined. Fifty-nine isolates were assigned to AG-4, 10 to AG-3, 42 to AG-2, and 11 to AG-1. Eight isolates did not anastomose with any of the tester strains or among themselves, and no isolate was assigned to AG-5. Pathogenicity of 35 isolates from different anastomosis groups on hypocotyls and/or leaves of kidney bean, soybean, red pepper, radish, sugar beet, and cabbage varied considerably, from nonvirulent to highly virulent. In general, anastomosis groups lacked host specificity. The optimum growth temperature for isolates tested varied from 20 to 30 C.