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Expression of Ergot Resistance in Pearl Millet Under Artificially Induced Epidemic Conditions. R. P. Thakur, Senior plant pathologist, Cereals Program, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India; S. B. King, and V. P. Rao. Principal plant pathologist, and research associate, respectively, Cereals Program, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India. Phytopathology 79:1323-1326. Accepted for publication 12 April 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-1323.

Resistance to ergot (Claviceps fusiformis) in pearl millet, previously identified by using an inoculation technique for field screening, was tested under artificially induced epidemics in the field and greenhouse. The epidemic conditions were created by repeated spray inoculation of protogynous panicles with an aqueous honeydew conidial suspension (1 × 10⁶ conidia/ml) under conditions of high relative humidity (>90%) or panicle wetness (>80%) and moderate temperature (20–30 C). There were no significant differences in ergot reactions under artificially induced epidemic conditions and field screening for resistant (=10% mean ergot severity) or susceptible (=30% mean ergot severity) cultivars. However, cultivars that were moderately resistant (10–30% ergot severity) in field screening showed very low ergot (<2% mean severity) that were comparable to the highly resistant cultivars, under epidemic conditions both in field and greenhouse. The results suggest that an ergot severity threshold level of 20–30% in field screening should provide adequate levels of functional field resistance under natural ergot epidemic conditions. Pearl millet cultivars with moderate levels of ergot resistance and having desirable agronomic traits may be suitable for cultivation in areas where ergot is of economic importance.