Management of Alternaria blight of rapeseed-mustard

Field experiments were conducted during 2007–08 to 2009–10 crop seasons to identify effective and economic fungicides and resistant genotypes for the management of Alternaria blight caused by Alternaria brassicae (Berk) Sacc. and Alternaria brassicicola (Schw.) Wiltshire. Three sprays of Quintal (Iprodione 25% + Carbendazim 25%) @ 0.2% with disease intensity, 24.44 and Area Under Disease Progress Curve (AUDPC), 399.40 resulted in highest disease reduction followed by 0.15% concentration of the same fungicide with 27.33% disease intensity and 545.25 AUDPC. The next effective fungicide was Tilt (Propiconazole 25 EC) @ 0.1% and 0.075%, respectively. Maximum yield of 1433.33 Kg/ha and test weight of 6.09g were also recorded with Quintal (0.2%) followed by Tilt (0.1%), respectively. These treatments avoided maximum loss 35.46% and 32.32%, respectively. Three sprays of Propineb (Antracol 70 WP) @ 0.2% recorded benefit-cost ratio of 8.58 proved most economical. Genotypes NUDB-26-11, HNS-004, ONK-1, PHR-2 proved resistant and genotypes DMH-1, EC-339000, PBN-2004-1, Kiran, GSL-1, EC-338997 proved moderately resistant against Alternaria blight. As an friendly management, the extracts of ten plants species were found effective in inhibiting the growth of the pathogen in vitro, and degree of inhibition varied from 33.20 to 67.60% at 5% and 48.90 to 77.80% at 10% concentration, respectively. Maximum inhibition (77.80%) was recorded with leaf extract of Eucalyptus sp., followed by leaf extract of Dhatura (72.20%) and bulb extract of garlic (64.40). Eucalyptus also inhibited spore germination up to 100% at both the concentration proved most fungitoxic against the pathogen, followed by Tulsi (92.60%) and Garlic (76.10%) at 10% concentration.