Efficacy of Fungicides against Spot Blotch Disease of Wheat Caused by Bipolaris sorokiniana (Sacc.) Shoemaker

Abstract

Spot blotch, caused by Bipolaris sorokiniana, is one of the most destructive foliar diseases limiting wheat productivity, particularly under the warm and humid conditions of the Indo-Gangetic Plains. The present study was conducted during the 2024-25 Rabi season at the Norman E. Borlaug Crop Research Centre, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, to evaluate the efficacy of different fungicides against spot blotch under field conditions. The experiment comprised eight fungicidal treatments, including triazoles, strobilurins, their combinations, and a contact fungicide, together with an untreated control. Two foliar sprays were applied at 10-day intervals after disease initiation. Disease severity was assessed as percentage disease intensity (PDI), while grain yield and the percentage increase in yield over the untreated control were recorded. Among the treatments, tebuconazole 50% + trifloxystrobin 25% (0.10%) was the most effective in reducing disease severity and increasing yield. The findings indicate that triazole-strobilurin combination fungicides provided better management of spot blotch, which may be associated with their complementary preventive and curative modes of action and systemic activity.