Disease scenario and virulence pattern of major wheat pathogens occurring in indo-gangetic plains of West Bengal, India

Owing to climate change, the disease dynamics have been altered across important wheat growing belts of our country. Considering the importance of wheat in West Bengal, a survey was conducted across different districts of the state in the year 2019-20 and 2020-21 for monitoring the present status of foliar diseases of wheat. In the year 2019-20, seven locations across two districts, Nadia and Murshidabad, were surveyed while twenty locations across six districts were surveyed in the following year. In 2019-20, high spot blotch severity (43.21%) was observed in four locations of Nadia district, while Karimpur of Nadia (24.69%) and Jalangi in Murshidabad district recorded lower severity (24.69). Highest leaf rust severity score was recorded in Jalangi, Murshidabad (100 S), while lowest severity was observed in Karimpur Parisha in Nadia district (20 S). In 2020-21, highest spot blotch severity (59.26%) was recorded in two locations (Jalangi, Dhanirpur-Bhaduripara) of Murshidabad district, while lowest disease severity (9.88%) was observed in BaraAduliya (Krishnanagar) of Nadia. Highest rust severity (80 S) was observed in Nadia District while lowest severity (20 S) was recorded in four locations of Nadia (Bara Aduliya, Krishnanagar, Magurakhod, Bhajanghat), one in Birbhum (Tarapith) and Murshidabad (Raninagar). Pathogen identification revealed rust pathotype 77-9 (121R60-1) was most abundant in both the consecutive years, while isolate WB7 of Bipolaris sorokiniana (Accession no. MT804348) was most aggressive among the isolates collected. The identified pathotypes can be used further for screening of genotypes.