Some characteristic of Rhizoctonia spp. in sharp eyespot of wheat

Abstract

Isolates of Rhizttctonia sp. with multinucleate and binucleate cells were obtained from sharp eyespot lesions on wheat culms in Olsztyn region. (NE Poland). These isolates were compared to isolates of AG-4 and GAG-1 testers with reference to cultural morphology of colony, growth rate, hyphal anastomosis and pathogenicity to wheat seedlings. The wheat binucleate isolates were similar in morphology of colonies and anastomosed with the Ceratubasidium anastomosis group GAG-1 tester isolates of R. cerealis. Growth rates on PDA ranged from 9 to 11 mm/24h for wheat isolates and from l to 11 mm/24 h for tester isolates GAG-1 of R. cerealis. The wheat multinucleate isolates were similar in morphology of colonies and anastomosed with Rhizoctonia solani Kühn group AG-4 tester isolate. R. solani AG-4 isolates were morphologically distinct from the R. cerealis isolates. These isolates on PDA were dark and grow rapidly (20-30 mm diam./24 h/20°C) and significantly contrasted with slowly growing white-creamy isolates of R. cerealis (GAG-1). Isolates of R. solani (AG-4) and R. cerealis (GAG-I) developed sharp eyespot lesions on culms and white head symptoms typical of the disease. None of the wheat isolates of R. cerealis (GAG-I) caused root-rot on wheat seedlings. In the present work the classification system of vegetative groups of Rhizoctonia spp. in present work is also discussed.