A Seedling Inoculation Technique for Detecting Downy Mildew Resistance in Pearl Millet

Abstract

A seedling inoculation technique producing consistently heavy downy mildew (Sclerospora graminicola) infection ( more than or equal to 85%) on susceptible pearl millet (Pennisetum americanum) cultivars is described. It involves inoculation of seedlings in pots with an aq. suspension of sporangia applied by a microsyringe. Infection was greatest in seedlings inoculated before the first leaf unfolded and sharply decreased when the seedlings were inoculated at a later stage. The technique, which is more effective than field inoculation in producing downy mildew, resembles natural infection but allows inoculum uniformity and does not affect normal host activity. It is valuable for checking the reliability of field-identified resistance and for detecting high levels of resistance in key material