Evaluation and standardization of growth stage of wheat against spot blotch caused by Bipolaris sorokiniana

EVALUATION OF WHEAT GENOTYPES FOR SPOT BLOTCH (Bipolaris sorokiniana Sacc.) RESISTANCE AT KHAIRAHANI, CHITWAN

“…Scoring of disease at suitable growth stage is very important to understand the disease epidemiology and assess the crop loss which helps in developing disease management strategy (Deepshikha et al, 2017). After all the genotypes were at heading stage, double digit scoring was done visually, five times at a weekly interval (90 DAS, 97 DAS, 104 DAS, 111 DAS and 118 DAS).…”

“…It is a disease caused by hemibiotrophic fungus Bipolaris sorokiniana (Sacc.) Shoem which is most active under high relative humidity and temperature along with low fertility status (Deepshikha et al, 2017;Basnet et al, 2022;Duveiller and Dubin, 2002). Growth of B. sorokiniana is favored by moderate to warm temperature i.e.…”

“…The disease occurs in seedling stage and the severity of disease increases as the plant gets older (Alam et al, 1998). The early symptoms exhibited by spot blotch infected plants are small, round, brown colored lesions that eventually enlarge to form larger elongated blotches in susceptible varieties which may further coalesce resulting necrotic patches (Deepshikha et al, 2017;Gupta et al, 2018;Kumar et al, 2020). Though these are the identifying characters of the disease, confirmation of the pathogen can be done only after the laboratory test.…”

“…Spot blotch has expanded to cooler, traditional irrigated rice-wheat cropping areas due to adaptation of the pathogen, climate change and broad host range (van Ginkel and Rajaram, 1998). Hence, there is need of identification of resistance source for developing spot resistant wheat varieties (Joshi et al, 2007;Deepshikha et al, 2017). A lot of breeding and pathology resources are being spent for developing high-yielding spot blotch resistant wheat genotypes in warm wheat growing environments of South Asia (Sharma and Duveiller, 2006).…”

“…Even in the resistant genotypes the disease severity increase due to delayed seeding and cause high yield loss (Duveiller et al, 2005). Resistance of the cultivar and the climatic condition during the crop period highly influence the yield loss by spot blotch (Deepshikha et al, 2017).…”