Spray scheduling of fungicide Difenoconazole 25EC for the management of Stemphylium blight of onion (Allium cepa L.)

A field experiment was conducted during rabi season of 2015 at the Vegetable Research Centre of G.B. Pant University of Agricuture ant Technology, Pantnagar to evaluate the effect of different number of fungicidal sprays of a standard fungicide Difenoconazole 25EC for the management of Stemphylium blight of onion caused by Stemphylium vesicarium (Wallr.) Simmons. The experiment was laid out in RBD and different number of foliar sprays of difenoconazole viz. 3, 4, 5 and 6 sprays was tested starting from 15 and 30 days after transplanting right up to 90 days after transplanting with three replications of each treatment. Results of the experiment revealed that 5 foliar sprays were most effective giving the highest per cent disease control (23.37%) followed by 6 sprays. The highest marketable bulb yield (22.82 t ha-1) was also obtained in the treatment with 5 sprays. The economic analysis of treatments revealed that 5 sprays gave the maximum net return due to treatment (R68,400 ha-1) and highest percent avoidable loss (29.97%), along with maximum net benefit-cost (B:C) ratio of 5.64, followed by 4 sprays. Therefore, 5 sprays of Difenoconazole 25EC at the rate of 125 g a.i. ha-1 was found as the most effective and economical management strategy against Stemphylium blight of onion under tarai region of Uttarakhand.