CULTURAL AND MORPHOLOGICAL CHARACTERIZATION OF Rhizoctonia solani ISOLATES ASSOCIATED WITH DAM

Abstract

A total of 50 isolates of Rhizoctonia solani was isolated from infected roots and stem base of diseased cotton seedlings collected from different locations throughout Bangladesh. Of them 29 were isolated from samples of Hill cotton. Out of 29 samples of Hill cotton seedlings 16 were collected from 16 locations of Bandarban district, 10 from 10 locations of Rangamati district and other three from 3 locations of Gazipur district. Rest of 21 isolates were associated with samples of 4 American cotton varieties namely CB-3, CB-5 and CB-9, CB-I a grown in the district of Gazipur, Dhaka, Rangpur, Pabna, Kushtia, Meherpur and Natore. The isolates were designated with first letter of district names and first two letters of upzilla names from where the diseased samples were collected along with a serial number. A series of experiments were conducted for characterization of 50 isolates of R. solani associated with cotton grown in different locations of Bangladesh. A total of 50 isolates of R. solani were found to infect the colton seedling. Remarkable cultural and morphological variations were found among the isolates. Three types of mycelium and colony structures viz compact, slightly fluffy or fluffy were observed. The colony color was very light brown, light brown, brown and dark brown. Pattern of sclerotia distribution was throughout the plate, at centre, periphery and irregular.