Development of Tolerance and Cross-tolerance in Macrophomina phaseolina Against Fungicides

The study on development of tolerance and cross- tolerance in Macrophomina phaseolina revealed that a common trend of increasing colony diameter of the test fungus was observed in successive generations against all the test fungicides but the rate of increase was not same from generation to generation. The percentage increase in colony diameter of test fungus was varied from 6.2-52.8 % for propineb 70 WP, 1.6-104.8% for prochloraz 45 EC, 5.0-90.7% for flusilazole 40 EC and 7.2-100.0%for difenocenezole 25 EC The development of cross-tolerance in M. phaseolina has been evident among the four fungicides, viz., propineb 70 WP, prochloraz 45 EC, difenocenezole 25 EC and flusilazole 40 EC, exhibited positive cross-tolerance against other than the fungicides which was already adapted to M. phaseolina.