Spatial and Temporal Variability in Wheat Yellow Rust Prevalence Across the Pak-Afghan Bordering Hindukush Region of Pakistan: A Four-Year Surveillance Study (2019–2022)

The yellow rust caused by Puccinia striiformis has been shown to be very frequent and highly diverse in the Himalayan region of Pakistan, though little is known about the disease in the Pak-Afghan bordering Hindukush region of Pakistan. We assessed the spatial and temporal variability in the prevalence of wheat yellow rust across the Hindukush region of Pakistan through a comprehensive 4-year surveillance effort (2019–2022). Covering 1145 fields across multiple districts, the surveillance provided insights into yellow rust distribution in different regions: Peshawar Valley, Western Hindukush, Northern Hindukush and Southern Hindukush. Yellow rust emerged as the primary wheat disease in the studied areas, affecting 83% of surveyed fields, with 29% exhibiting a severity of ≥ 50%. The highest incidence occurred in Peshawar Valley (98%) followed by Northern Hindukush (83%), Western Hindukush (78%) and Southern Hindukush (78%). Severity was notably high in Peshawar Valley and Western Hindukush (33% each), whereas Southern Hindukush recorded the lowest (17%). Over the years, yellow rust manifested with high pressure in 2020 (97%) and 2019 (96%), transitioning to low pressure in 2021 (79%) and 2022 (60%). Among varieties scored, Galaxy, Pirsabak-2013, Pirsabak-2005 and Pakhtunkhwa-2015 exhibited high susceptibility (ACI > 40), whereas Fakhre-Bakkar-2017, Anaaj-2017, Barani-2017 and Akbar-2019 demonstrated resistant reactions (ACI < 10). This study's findings offer valuable insights for plant breeding programmes aimed at enhancing crop productivity in the Hindukush region of Pakistan while considering the relative regional risk of the disease.