INDUCED SYSTEMIC RESISTANCE PROTECTS PEARL-MILLET PLANTS AGAINST DOWNY MILDEW DISEASE DUE TO SCLEROSPORA-GRAMINICOLA

Three-day-old seedlings of pearl millet (Pennisetum glaucum), when roo t-dip inoculated with different concentrations of zoospores of Scleros pora graminicola, had increasing degrees of downy mildew disease incid ence with increasing inoculum load. Inoculation of plants with 6000 zo ospores ml-1 caused infection in all plants but resulted in only 18% d isease as evidenced by external symptom manifestation. The plants trea ted to this suboptimal level of zoospores, when challenged after 4-6 d ays with 40 000 zoospores ml-1 remained predominantly healthy compared with the controls, suggesting induction of resistance by the suboptim al dose of inoculum used. The resistance induced was systemic and prot ected tillers and inflorescences.