Cultural and morphological variability among Rhizoctonia solani f. sp. sasakii isolates: An incitant of banded leaf and sheath blight of maize

Abstract

The genus Rhizoctonia is a ubiquitous soilborne necrotroph that inflicts damage on a wide range of economically important crops. Investigation on Rhizoctonia solani f. sp. sasakii isolates causing banded leaf and sheath blight of maize was undertaken to study the morpho-molecular variation and vegetative compatibility. During the survey, fourty pathogen isolates were collected from diverse geographical locations and their cultural and morphological specificity was studied followed by their molecular distinctiveness. Cultural and morphological characters viz., mycelial growth, colony colour, colony texture, hyphal width and angle of branching revealed the occurrence of variability among the isolates. Based on their growth on PDA medium, pathogen isolates were classified into slow (< 20 mm/day), moderate (30 mm/day) and fast (40 mm/day). Colony colour ranged from white to light brown and colony texture being sparse to cottony fluffy. All the isolates recorded a hyphal width of 2-4 µm and produced light to dark brown coloured sclerotia. Based on number of sclerotia produced, isolates were grouped into poor (3-10), moderate (11-30) and high (> 30).