Management of purple blotch and Stemphylium blight of onion in Tarai and Bhabar regions of Uttarakhand, India

Abstract

Purple blotch [Alternaria porri] (Ellis) Cif.) and Stemphylium blight [Stemphylium vesicarium] (Wallr.) E. Simmons) of onion cause serious problems in onion seed crop in Tarai and Bhabar region of Uttarakhand. In present study different bio agents and fungicides have been evaluated in vivo against both the diseases. The severity of both purple blotch and Stemphylium blight varied in both Tarai and Bhabar region and even more pronounced in Tarai region than in Bhabar region. A correlation was observed in between the severity of both the diseases with the yield in seed crop. The minimum disease severity of purple blotch and stemphylium blight with the foliar spray of mancozeb (@ 0.3%) + monochrotophos (@ 0.05%) were observed 2.67% and 2.57% respectively with the total yield of seed was1844.44 kg/ha over check 893.33 kg/ha in 2011. While with the foliar spray of neembicidine (@ 0.3%) disease severity of both the diseases were 5.57% and 4.78% respectively providing a yield of 1827.78kg/ha in seed crop of onion in 2011. Amongst the applied bio-agents, the foliar spray of Trichoderma harzianum (@ 1%) the disease severity of purple blotch and stemphylium blight were recorded 15.44% and 13.11% respectively which was found to be most effective in delaying the disease appearance and providing a yield of 1134.44kg/ha in 2011. However, all the treatments helped to reduce both the diseases in comparison with check.