Lakshman SS, Rao S Chander and Godke MK
Sunflower is a new emerging oilseed crop which can grown through-out the year. In West Bengal this crop mainly grow in rabi season which suffers many biotic stresses, out of which soil borne diseases are of great economic importance. A field study was conducted by AICRP on Sunflower, Nimpith Centre to identify the best management approaches to overcome the yield loss due to wilt of sunflower. It was observed that most of the fungal and bacterial antagonists tested were found effective against soil borne diseases in-vivo conditions. The isolates of fungal antagonists Trichoderma viride (Tv), and Trichoderma harzianum (Th) and one isolate of bacterial antagonist Pseudomonas fluorescens (Pf) were found very effective to control this seed borne disease when used as bio-agents. The above antagonists (bio-agents) with their combinations found highly effective against all the soil borne pathogens causing the sunflower wilt under in vivo conditions were used for seed, soil and seed+soil treatments to observe their effectiveness on seed germination, seedling emergence, early seedling growth and resistance of wilt incidence in sunflower cv. DRSH-1. Post studies further revealed that seed+seedling+soil application of the antagonists resulted in lesser wilt incidence compared to only seed or soil application of these antagonists resulting higher seed yield in farmer’s field. The lowest mortality of sunflower plants either in seedling stage or in mature stage also observed when the bio-inoculants were used in combination (T. harzianum+P. fluorescens (5.0g/lit 5.0g +5.0g/ kg of seed) and when the combination was used as seed inoculants and also used for spraying at the crown region before first and second irrigation. The data across of the years of study on demonstration fields, indicated that economic advantage in terms of the Benefit: Cost (B:C) ratio of the farmers under improved method of sunflower cultivation with seed treatments and application of bioinoculants results higher Benefit: Cost (B:C) ratio higher was recorded 1.41 (2014-15) and 1.45 (2015-16) which were much higher compared to conventional cultivation systems/ Farmer’s Practice, 1.06 (2014-15)-1.18 (2015-16). The conclusion of the present study is that T. viride, P. fluorescens and T. harzianum and their combinations have significant role on to effective management of sunflower wilt in West Bengal.
