Characterization and Pathogenicity of Rhizoctonia spp. from Onion in Amasya, Turkey

Forty-two isolates of Rhizoctonia spp. were obtained from onion in Amasya, Turkey. Of these, 29% were Rhizoctonia solani (AG-4), 69% were Waitea circinata var. zeae (Rhizoctonia zeae) and 2% were binucleate Rhizoctonia (AG-B). Most of the isolates were recovered from rhizosphere soil. In pathogenicity tests on onion, R. solani AG-4 caused the greatest disease severity, those of W. circinata var. zeae were moderately virulent but binucleate Rhizoctonia isolates were of low virulence. This is the first report of binucleate Rhizoctonia AG-B and W. circinata var. zeae occurring on onion in Turkey