BIO-SAFETY MANAGEMENT AND CHEMICAL INVESTIGATION OF RADISH ROOT TOWARDS ALTERNARIA BLIGHT OF MUSTARD (Brassica napus)

Abstract

An investigation was carried out at Hajee Mohammad Danesh Science and Technology University, Dinajpur during the period of 2008-09 to explore the possibility of controlling Alternaria blight of mustard caused by Alternaria brassicae and A. brassicicola. A promising mustard variety BARI-9 was used in this investigation. A total of eight management practices viz., aqueous radish root extract (1:1), aqueous radish root extract (1:2), petroleum ether radish root extract (1:1), petroleum ether radish root extract (1:2), BAU-Biofungicide(0.2%), Iprodione2 spary (0.25%)and Iprodione-3 (0.25%)spary including a control (plain water spray) were applied as foliar spray. The Alternaria symptom wass appeared on lower leaves at 27-days old plants and spraying were started from the time of disease initiation with 7 to 14-day interval. Among the treatments, Iprodione-3-spray showed superior performance in controlling Alternaria blight of mustard. Iprodione-3 spray reduced leaf area diseased, siliqua area diseased, percent plant infection, percent leaf infection, percent siliqua infection and number of spot per siliqua by 69.92%, 66.41%, 35.08%, 65.17%, 80.13% and 57.23%, respectively and increased seed yield by 55.68% over control. The second best performance against Alternaria blight was obtained from Iprodione-2 spray. Radish root extracts was sprayed with 7-day interval. Other than Iprodione, petroleum ether radish root extract (1:1) performed best in controlling the disease. Spray of petroleum ether radish root extract (1:1) reduced leaf area diseased, siliqua area diseased, percent plant infection, percent leaf infection, percent siliqua infection and number of spot per siliqua by 34.87%, 44.39%, 20.07%, 27.33%, 34.07% and 39.13%, respectively and increased seed yield by 35.93% over control. BAU-Biofungicide was sprayed twice with 14-day intervals and also showed significant result next to radish root petroleum ether extract (1:1) and increased seed yield by 25.64% over control. Regarding the economic consideration, iprodione-2 spray gave the maximum return (BCR=3.57) while the control treatment showed the lowest return (BCR=0.82). Petroleum ether radish root extract (1:1) as eco-friendly management practice exhibited good performance next to Iprodione (BCR=1.96). In laboratory investigation with Thin Layer Chromatography (TLC) of petroleum ether radish root extract towards antifungal compounds showed one distinct compound and mixture of compounds. The distinct compound showed high Ry value indicate non-polar type. Therefore, it may be concluded that Alternaria blight of mustard can be controlled with petroleum ether radish root extract (1:1) as foliar spray reducing maximum disease incidence and providing satisfactory higher seed yield in the sense of environmental pathology.