Time-temperature relationships for the inactivation of sclerotia of Macrophomina phaseolina

Abstract

The viability of sclerotia of Macrophomina phaseolina was tested in both wet and dry soil under simulated elevated temperatures in either constant, cyclic or short temperature regimes. In wet soil viability was reduced to zero by a constant temperature of 55βC and above for 1 day or a minimum oven temperature of 50βC for 3 days. Viability of sclerotia was destroyed by a 2 h temperature cycle for 7 days at 60β or 14 days at 55βC. At 50βC up to 11% sclerotia remained viable after 21 days. In dry soil at 60βC, a 7-day constant temperature or a 21 days 2 h temperature cycle reduced sclerotial viability by 88 and 76%, respectively. Data on time and temperature relationships on loss in viability of sclerotia in soil can be used to predict efficacy of soil solarization.