Variation among isolates of Macrophomina phaseolina causing root rot of groundnut

The fourteen isolates of Macrophomina phaseolina were studied for their discernible characters such as the colour of mycelium, pigmentation of substrate, type and amount of mycelial growth, number of sclerotia, virulence and nutritional requirement. All the isolates were found to be pathogenic though they differed in the per cent disease incidence. The isolate BKN was highly virulent as compared to other isolates. The mycelial growth of isolates of M. phaseolina on Czapekís dox agar basal medium with different carbon, nitrogen sources, temperature and pH varied.