Studies on Management of Alternaria blight of Mustard

Abstract

Mustard an important oilseed crop belonging to Crucifereae family occupies nearly 70 percent of total oilseed area under cultivation. Several biotic and abiotic factors have been identified for the low productivity of mustard in India. In the biotic factors, Alternaria blight is serious problems for the successful cultivation of mustard crop in India. In the present investigation extensive studies on management of Alternaria blight of Mustard” (Alternaria brassicae). Alternaria blight is the most severe yield destabilizing factors causing reduction from 35 to 45 per cent and inflicts very severe losses upto 70 per cent in yellow and brown sarson. The symptoms of Alterrnaria blight appeared as brown and grayish with typical concentric rings on the leaves. In later stages of disease development, several spots coalesce produce leaf blight symptoms in several attacks the spot coalesce which result into withering and shedding of leaves. Circular to linear, dark brown lesion also develop on stem and pods, which are elongated at later stage. Infected pods produce small, discolored, shriveled and grey to brown in colour seed. Studies were conducted on the efficacy of seven fungicides and seven botenical extracts against Alternaria brassicae under in vitro condition. In seven fungicide, five fungicide viz. Mancozeb 75% WP, Propiconazole 25% EC, Azoxistrobin 25% EC, Hexaconazole 5% EC and Carbendazim 50% WP+Mancozeb 75% WP were found to 100% inhibit mycelial growth of Alternaria brassicae at 50, 75, 100 ppm concentration after after 7th day incubation. In botanical extracts the maximum mycelial growth inhibition was recorded by 66.57%, 72.22% and 77.77% in Turmeric rhizome extract followed by 59.36%, 68.83% and 72.55% in Garlic clove extract at 2, 5 and 10% concentration after 7th day incubation. Study on effect of different date of showing on disease incidence and severity of Alternaria blight of Mustard, and yield q/ha starting from 15th Oct to 25th November at 10 day intervals. The minimum percent disease incidence, severity and maximum yield was recorded 21.60% ,18.20% and 17.20 q/ha in 15th October sown crop followed by 22.60%, 24.30% and 15.90 q/ha in 25th October sown crop respectively. Experiments were also conducted for integrated management of the disease under in field condition. The lowest percent disease incidence, severity and highest yield was observed 6.00%, 6.60% and 19.00 q/ha foliar application Propiconazole 25% EC @ 0.1% concentration followed by 9.7%, 8.10% and 17.64 q/ha in foliar application of Cymoxanil 8 % + Mancozeb 64% WP @ 0.1% respectively.