METHODS FOR SCREENING MAIZE AGAINST DOWNY MILDEW PERONOSCLEROSPORA-SORGHI

Methods of inoculum delivery and timing of test-row planting were asse ssed for efficacy in promoting development of downy mildew (Peronoscle rospora sorghi) in susceptible maize, and For cost of implementation i n terms of personnel and labour. Direct inoculation of pre germinated seed of spreader rows resulted in consistent and high incidence of dow ny mildew infected plants and required substantially less labour and i noculum than the spray inoculation of spreader rows. The optimum time to plant test rows was around 15 days after inoculation of spreader ro ws. Eight breeding lines were screened for resistance to downy mildew using the revised inoculation method. After one cycle of screening wit h the new method, resistance levels improved by a range of 0-44% over the previous cycle.