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Characterization of Rhizoctonia solani AG-8 from Bare Patches by Pectic Isozyme (Zymogram) and Anastomosis Techniques. G. C. MacNish, Department of Agriculture, Esperance Agricultural Centre, PMB50, Esperance, WA, Australia 6450; D. E. Carling(2), and K. A. Brainard(3). (2)(3)University of Alaska Fairbanks, Agricultural and Forestry Experimental Station, 533 East Fireweed, Palmer 99645. Phytopathology 83:922-927. Accepted for publication 1 April 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-922.

Isolates of Rhizoctonia solani AG-8 collected from Rhizoctonia bare patches at two locations in Western Australia were characterized by pectic isozyme (zymogram) and anastomosis techniques. All isolates collected from the same patch at the same time and at different times up to 10 mo apart were members of the same zymogram group. Anastomosis techniques demonstrated that these multiple isolates from the same patch were members of the same clone, as indicated by the clonal anastomosis reaction. Anastomosis reactions also indicated that isolates from the same zymogram group but from different patches in the same field or farm may or may not be members of the same clone. In general, patches with the same zymogram group and in close proximity to one another are more likely to be of the same clone than are patches separated by greater distances. Thus, the zymogram technique demonstrated the existence of distinct groups (currently five) within R. solani AG-8, and the anastomosis technique demonstrated there may be many different clones within each zymogram group. In general, the chance of isolates collected from patches caused by the same zymogram group being members of the same clone decreases as distance between patches increases. However, clonal relationships have been detected between isolates of the same zymogram group collected from patches separated by hundreds of kilometers in Australia and in one case in Oregon. Some possible explanations for the spread of clones are presented.

Additional keywords: anastomosis group.