Management of onion twister disease through foliar nutrients and fungicide applications

Abstract

A field experiment was conducted at Haveli Farm, College of Horticulture, Bagalkot, during the Kharif seasons of 2023-24 and 2024-25 to evaluate the effect of integrated nutrient management (INM) on twister disease severity and yield of onion (Allium cepa L., cv. Arka Kalyan). Eight treatments involving foliar application of micronutrients viz., Boron (B), Zinc (Zn), Sulfur (S), Potassium nitrate (KNO₃), calcium nitrate and commercial micronutrient mixtures combined with a combi fungicide product (Azoxystrobin 11% + Tebuconazole 18.3% W/W SC) were tested in a randomized complete block design with three replications. Disease severity was assessed using a 0-5 scale, and per cent disease index (PDI), percent disease reduction over control (PDROC), bulb yield (t/ha) and economic returns through incremental cost-benefit ratio (ICBR) were measured. Across both seasons, foliar application of Boron 20% @ 1 g/l with fungicide (Azoxystrobin 11% + Tebuconazole 18.3% W/W SC) (T2) consistently recorded the lowest disease severity (PDI 23.38% and 21.35%), highest PDROC (55.46% and 57.47%), maximum bulb yield (27.37 and 30.95 t/ha) and superior economic returns (ICBR 1:2.46 and 1:3.24). Other nutrient-fungicide combinations, including calcium nitrate, potassium nitrate and micronutrient mixtures such as Arka Vegetable Special, also significantly reduced disease incidence and improved yield. These results indicate that integrating targeted foliar nutrients with fungicide applications provides an effective, economically viable and environmentally sustainable strategy for managing twister disease in onion.