Pathogenic variability in Exserohilum turcicum and resistance to leaf blight in sorghum

Leaf blight caused by Exserohilum turcicum is a widely prevalent and economically important disease of sorghum in relatively cooler and humid regions of the world. Disease management through host plant resistance is the most effective strategy, but this requires information on population biology of the pathogen and the effect of environment. We studied pathogenic variability and disease resistance to leaf blight in sorghum through a collaborative Sorghum Leaf Blight Virulence Nursery (SLBVN). The SLBVN consisting of 20 diverse sorghum lines were tested at three locations in India for 1-3 seasons (2007-09). Leaf blight severity recorded at the soft-dough stage of the crop varied significantly among lines, years and locations, indicating potential differences in virulence of E. turcicum populations at different locations. Some sorghum lines showed differential reactions while lines (IS 2683, IS 3490, IS 9303, IS 10775, IS 12466, IS 18668, IS 19163, IS 25400 and IS 26863) exhibited resistance stability across environments (locations × years). These lines could be potential sources of resistance for utilization in leaf blight resistance breeding program.