Evaluation of aggressiveness of different isolates of Rizoctonia solani causing sheath blight disease of rice collected from different districts of Chhattisgarh

Abstract

Awareness of the pathogenicity and aggressiveness nature of each pathogenic microbe is necessary not only to understand the expression of symptoms, but also contribute to the sheath blight disease control programme. The intensive survey of sheath blight infected farmers fields during the kharif 2015-16 at forty one locations of fifteen districts of Chhattisgarh plane were carried out and the disease samples were collected at maximum tillering stage of rice. Sheath blight and banded blight symptoms were examined for detail study. Naturally infected plant samples of sheath blight have been obtained from the fields in the laboratory for isolation and purification of sheath blight fungus. The pathogen was isolated on PDA and the subcultures were purified using a single hyphal tip cutting method and kept on PDA at 28 ± 2 °C. Samples infected with the sheath blight disease of paddy were collected from different districts of Chhattisgarh for systematic study of sheath blight symptoms in rice. The total number of fifty-eight isolates were confirmed by the proof of the Koch postulates and classified in the category as weakly aggressive, moderately aggressive, aggressive and highly aggressive. The seven isolates were recorded as highly aggressive and the maximum PDI 98.15 was shown by the isolate no. RS57.