Influence of Cropping Systems on Macrophomina phaseolina Populations in Soil. S. K. Singh, Post-doctoral Fellow, Legumes Pathology, ICRISAT, Patancheru P.O., Andhra Pradesh 502 324, India. Y. L. Nene, and M. V. Reddy. Deputy Director General, and Senior Plant Pathologist, Legumes Pathology, ICRISAT, Patancheru P.O., Andhra Pradesh 502 324, India. Plant Dis. 74:812-814. Accepted for publication 1 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0812.

Cumulative effects of 15 crop combinations and rotations on populations of sclerotia of Macrophomina phaseolina in soil were studied during the fifth year of a Vertisol cropping system experiment at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Center in Patancheru, India. Higher counts of sclerotia were recorded in the intercropping systems of sorghum (Sorghum bicolor) or cowpea (Vigna sinensis) with pigeon pea (Cajanus cajan) than in single-cropping systems. The highest counts of sclerotia were recorded in plots where sorghum was intercropped continuously with pigeon pea in both the rainy and postrainy seasons. An increase in the populations of sclerotia was also recorded when rainy season sorghum was followed by either safflower (Carthamus tinctorius) or chickpea (Cicer arietinum). Cropping systems with fallow in the rainy season, followed by sorghum or chickpea in the postrainy season, stabilized the inoculum density of M. phaseolina.