Response of Late Maturity Maize Lines and Hybrids to Southern Corn Leaf Blight Disease Caused by Bipolaris maydis

To evaluate resistance of maize late maturity lines and hybrids to southern corn leaf blight disease (Bipolaris maydis), an experiment was performed in randomized complete block design with three replications in Karaj and Sari during 2013, using seventeen maize lines and hybrids. Artificial inoculation was carried out two times, first by injection of spore suspension into the whorls of the plants at 3-4 leaf stage, and the second by inoculation of infected sorghum seed with the pathogen into whorls by bazooka at 6-8 leaf stage. Disease severity on leaves of inoculated plants was scored one month after the second inoculation. The results of analysis of variance and means comparison indicated significant differences among lines and hybrids for disease severity. Among eight hybrids, only KSC 708 (A679 × K19) exhibited resistance response (R). Five lines were moderately resistant (MR) among them two commercial lines MO17 and K19 had disease severity less than 10%. Based on the results of this experiment, two latter lines were recognized as favourable sources of resistance to the disease. Line K19 is the paternal parent of hybrid KSC 708 (A679 × K19) which was resistant in this investigation.