Biological characteristics of the pathogens from wheat sharp eyespot and corn sheath blight in hebei province

The biological characteristics of 130 and 21 Rhizoctonia isolates collected from wheat and corn in different areas of Hebei province in 2005 were tested.The result showed that the Rhizoctonia growth on different medium was clearly different.The order of growth speed on different medium was PDA mediamaize mediawater agar media.The Rhizoctonia can grow well on PDA medium with pH 4-9,the optimum pH value was pH6.The O-KOH dyeing results indicated that 122 isolates out of 130 Rhizoctonia isolates from wheat were Rhizoctonia cerealis with percentage of 93.85%,8 isolates were Rhizoctonia solani with percentage of 6.15%;2 isolates and 19 isolates out of 21 Rhizoctonia isolates from corn were Rhizoctonia cerealis with percentage of 9.52% and Rhizoctonia solanis with percentage of 90.48%,respectively.The pathogenicity of some typical isolates was valuated by artificial cross-inoculation.The results showed that the virulence of different isolates were different,the virulence of Rhizoctonia on original host was higher than that on the other hosts.