Distribution maps depicting geographical prevalence of rapeseed-mustard diseases in India

Among 50 microbes affecting rapeseed-mustard crops, 16 diseases are recognized as significant contributors to crop damage at various growth stages including downy mildew (DM) and white rust (WR) during the seedling stage, white rust at leaf development, Alternaria blight (AB) at stem elongation, Sclerotinia rot (SR) during flowering, and powdery mildew (PM) during silique development and ripening. Additionally, new pathogens such as Nigrospora oryzae, Fusarium equiseti, Alternaria citri, Erwinia carotovora pv. carotovora, and Sclerotium rolfsii have recently been identified. There was an average of 21% for WR severity, 26.6% for AB severity, 25.1% for PM severity, and 14.2% for SR incidence occurrence. In terms of per cent share these diseases account for 17.3, 32, 30, and 17%, respectively, of all major diseases affecting rapeseed-mustard crops in India. Disease initiation patterns varied depending on geographical and prevailing weather conditions. Data indicates that DM occurred between 8 and 11 days after sowing, WR (34 to 60 DAS), AB (34 to 89 DAS), SR (70 to 85 DAS), and PM (56 DAS to 90 DAS). Analysis of 20 years’ data highlights the maximum WR severity of 22.1% during the crop season 2019–2020, which is prevalent in 17 states. Among Brassica species, B. juncea exhibited the highest susceptibility to WR with an average of 27.1%, while B. carinata, B. napus, and B. rapa ssp. Yellow Sarson showed resistance. AB severity exhibited similar variations, with the highest percentage of 38.9% observed on E. sativa, followed by B. rapa ssp. Toria (37.3%), Yellow Sarson (34.9%), and B. juncea (31.1%). Conversely, B. carinata and B. napus had a low percentage of 22.1% and 26.0%, respectively, with a decreasing trend in Rajasthan, Haryana, and MP states. Since 1999, SR has emerged severely, reaching its peak incidence of 42.8% during 2014–2015, and then decreasing, probably due to changing weather and technological implications comprising judicious use of sulphur, nitrogen, and irrigation. The incidence of SR occurred in Yellow Sarson (51.2%), Toria (50.2%), Taramira (49.0%), B. napus (38.5%), and B. carinata (33.4%). Furthermore, PM severity was highest in B. juncea (43.2%), and Toria (28.6%), which has become an epidemic disease in 18 states of India, with a 10% rise in severity. These disease maps will be crucial for intellectuals to prioritize climate resilience and pathogen research.