Regional variability in leaf rust infestation across the Hindukush region of Pakistan as revealed through a four years surveillance effort made during 2019 to 2022

Abstract Despite the importance of leaf rust disease across Pakistan, limited information is available regarding its status in the Hindukush region of Pakistan. This study was designed to investigate the disease status in the region through the surveillance effort made during 2019 to 2022. The surveillance was comprised of 25 districts across four different regions viz: Peshawar Valley (5 districts), Southern Hindukush (7 districts), Western Hindukush (7 districts), and Northern Hindukush (6 districts). Although the disease observed was very low, it varied over years and across the different geographical locations. The incidence of the disease was high in Southern Hindukush (8% fields infected) and Peshawar Valley (4% fields), while the disease was observed with low frequency in Western Hindukush (1% fields) and Northern Hindukush (0% fields). The disease was observed in the maximum fields during 2022 (5%), followed by 2020 and 2021 (each with only 3% infected fields), while the disease was not observed during 2019. The average co-efficient of leaf rust infection was recorded the maximum for local land races (7.3), while it was found the minimum for most of the surveyed varieties (0.0). Although most of the recently developed varieties were observed with no leaf rust, sporadic appearance was observed on some host varieties like Pirsabak-2005, Pirsabak-2013 and Shahkar-2013. The overall low co-efficient of infection for the surveyed varieties could be either due to resistance in these varieties or the lack of favorable environmental conditions for the disease development. The information provided in the study could help breeders in identifying desirable wheat lines while considering the prevalence of the disease in the region.