Screening of Maize Genotypes against Southern Leaf Blight (Bipolaris Maydis) during summer in Rampur, Chitwan

Screening of 20 maize genotypes against Southern Leaf Blight of maize (Bipolaris maydis (Nisik) Shoemaker) was carried out in RCBD in National Maize Research Program, Rampur, Nepal during June to September, 2015. The area of research field was 315 m2. Each genotype had two rows per plot of 7.5m2 with two replication. Disease incidence was taken for three times at 43, 53 and 63 DAS. Disease scoring was done as percentage of leaf area infected on individual plant at 7 days interval starting from 58 days after sowing for 5 times and disease severity and mean AUDPC was calculated. Also the yield was calculated. Shade house experiment was carried out in a Completely Randomized Design with 3 replication on 20 genotypes by artificial inoculation at 3-4 leaf stage with a pure culture suspension of Bipolaris maydis (4x104conidia per ml) .and disease incidence and survival days of plant were recorded. Among the genotypes disease severity varied in the field. Highly significant differences were observed among the genotypes for Southern Leaf Blight severity, Area Under Disease Progress Curve and grain yield. Genotypes with mean AUDPC values from 200-250, 250-300 and above 300 were categorized as moderately resistant, moderately susceptible and susceptible. Disease severity was highest on genotype Rampur 24, 07 SADVI and lowest on BGBYPOP, RML-32/RM-17 and RAMS03F08. Highest maize yield (4.44 ton/ha) was recorded on RML-32/RML-17 and least (1.41 ton/ha) was obtained in ZM-627.In shade house, Rampur-24 followed by 07 SADVI, Rampur 27 died earlier and RML-32/RML-17 and BGBYPOP survived to the longest periods after inoculation. Disease Susceptibility pattern was similar in both field and shade house condition. The genotypes RML-32/RML-17, BGBYPOP, RAMS03F08 and TLBRS07F16 could be developed as resistant varieties to Southern Leaf Blight of maize and also as high yielders during summer under Chitwan and similar conditions