Evaluation of epidemiological factors against Bipolaris sorokiniana (Sacc.) Shoemaker on Wheat Spot Blotch

Abstract

Wheat (Triticum aestivum L.) belongs to the Poaceae family. It is India's second most important cereal crop, after rice in India and after maize in the world. Wheat is a self-pollinated, C3 plant that is grown primarily in temperate countries but also at higher elevations in tropical climates during the winter. It is grown in the mid-winter months of November to April. Spot blotch; Bipolaris sorokiniana (Sacc.) Shoemaker is a major disease of wheat in India. The experiments were conducted during the Rabi season of 2022-2023 and 2023-24. In this experiment, we did epidemiological studies on three wheat varieties; HD 2967, A 9-30-1 and Agra Local at SIF, ANDUA&T, Ayodhya. The disease favoured by moderate to warm temperatures (18-32°C) and particularly by humid, damp weather. Spot blotch is probably the most serious leaf blight disease of wheat in the mega-environment characterized by high temperature (coolest month >17°C) and high relative humidity. HD 2967 is highly resistant, with a PDI peak of 24 in both years and low RPD values. Suitable for places with similar weather conditions, reducing the impact of Spot Blotches. A 9-30-1 is highly susceptible, with PDI ranges of 88 and 89 in both years. RPD peaks show rapid disease progression under favorable conditions (warmth and wetness). Agra Local; similarly susceptible, with PDI peaks of 89 and 88 in both years, but slightly slower early progression than A 9-30-1. Agra Local and A 9-30-1 exhibit rapid PDI increases under warmer, wetter environments (e.g., weeks 9 and 13), whereas HD 2967 is less affected, most likely due to genetic resistance. Rainfall and warmer temperatures appear to be the primary causes of Spot Blotch development, especially in susceptible cultivars. HD 2967 variety is preferable for Spot Blotch prone areas in India due to its lower PDI, RPD and slower disease progression.