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Characterization of Anastomosis Group 11 (AG-11) of Rhizoctonia solani. D. E. Carling,University of Alaska Fairbanks, 533 E. Fireweed, Palmer 99645; C. S. Rothrock(2), G. C. MacNish(3), M. W. Sweetingham(4), K. A. Brainard(5), and S. W. Winters(6). (2)(6)Department of Plant Pathology, University of Arkansas, Fayetteville 72701; (3)Department of Agriculture, Esperance Agricultural Center, PMB 50, Esperance, WA 6450, Australia; (4)Department of Agriculture, Baron Hay Court, South Perth, WA 6151, Australia; (5)University of Alaska Fairbanks, 533 E. Fireweed, Palmer 99645. Phytopathology 84:1387-1393. Accepted for publication 22 August 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-1387.

Isolates of Rhizoctonia solani anastomosis group 11 (AG-11) were collected in Western Australia and Arkansas. Some isolates from each location fruited on 1.5% water agar, 2% V8-juice agar, and soil overlay plates and produced sexual structures typical of Thanatephorus cucumeris. Mycelium of isolates of AG-11 growing on potato-dextrose agar was white to light tan when young, but became brown to dark brown with age. Concentric rings of dark and light mycelium were visible in most cultures. Mature sclerotia were tan to light brown and were scattered over the agar surface. No anastomosis reactions (C0) were observed between paired isolates of AG-11 and anastomosis groups 1, 3–7, 9, and 10. C1 anastomosis reactions were observed between some isolates of AG-11 and some isolates of AG-2, -8, and -BI, indicating a distant or “bridging” anastomosis relationship with these three AG. Isolates of AG-11 were auxotrophic for thiamine. Isolates of AG-11 are known to damage lupine, soybean, and other plants in the field, and in greenhouse and growth chamber studies were shown to damage other crops, including cotton, radish, wheat, and potato.