Screening of mustard germplasms against powdery mildew disease of mustard under natural field conditions

Powdery mildew, a disease caused by the fungus Erysiphe cruciferarum Opiz. Ex Junell is a significant threat to mustard crops in India, particularly in Chhattisgarh. This disease frequently affects Indian mustard (Brassica juncea (L.) Czern. and Coss.) and can result in substantial yield losses. A total of 25 mustard germplasms were evaluated under natural field conditions during the Rabi 2024-25. Under natural field conditions, in both leaves and siliqua, none of the germplasms exhibited an immune reaction, as all were observed to be affected by the pathogen. In leaves, seven germplasms showed moderate resistance, nine germplasms showed susceptible reactions, and ten germplasms and Varuna (Susceptible Check) showed highly susceptible reactions against the powdery mildew disease. In siliqua, thirteen germplasms showed moderate resistance, three germplasms showed susceptible reactions and ten germplasms and Varuna (SC) showed highly susceptible reactions against the powdery mildew disease. In the field condition, disease severity was recorded weekly, and the Percent Disease Index (PDI) was calculated. The PDI values ranged from 12.96 to 91.30 among the germplasms in leaves, while they ranged from 14.67 to 94.07 in the siliquae. The highest PDI value was observed in GP-10 and GP-25, while the lowest was in GP-17 and GP-6, respectively, in leaves and siliquae.