Efficacy of Bio-agents and Neem Oil against Alternaria porri (Ellis) in Onion (Allium cepa L.)

Onion (Allium cepa L.) is one of the important cultivated vegetable crops and can be grown in temperate, tropical and sub-tropical climates. It is the important vegetable and spice crop and known as “Queen of the kitchen”. Area, Production and Productivity on onion in India (2020-21) was 16.54 million ha, 26.92 million Tones and 19.40 t/ha. There are many diseases and pests affecting onion. Among the diseases, majorly purple blotch, downy mildew, Stemphylium blight and basal rot attacks the onion and among the pests, onion thrips, red spider mite, onion fly attacks the onion. Among them, purple blotch of onion is one of the most severe diseases, which is caused by Alternaria porri which causes heavy losses in the onion. The treatments viz., Trichoderma viride, Pseudomonas fluorescens, Bacillus subtilis and neem oil were tested under field conditions against Alternaria porri during Zaid for their efficacy against the growth and disease parameters and an untreated plot will serve as control. At desired interval of days (45,60,75 DAT) readings were taken for growth parameters and disease intensity. Based on single trail, it was observed that among all treatments, seedling treatment with Trichoderma viride + Pseudomonas fluorescens + neem oil @ 5% showed the most significant results with maximum growth parameters and minimum disease intensity results followed by Trichoderma viride + Bacillus subtilis + neem oil @ 5% and the minimum growth parameters and maximum disease intensity was shown in untreated (control) plot.