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POSTERS: Epidemiology II

P-248 - Diminishing effects of heat stress on the development of stripe rust (Puccinia striiformis f. sp. tritici) on winter wheat

Tuesday, August 5, 2025
9:30 AM - 10:15 AM HST
Location: Exhibit Hall 3
Abstract Text: Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), has led to over $240 million in losses in Kansas wheat fields over the past five years. Historically, stripe rust development has been favored by cool, wet weather with periods of high temperature suppressing disease development. However, recent field observations suggest that the suppressive effects of high temperatures on Pst may be diminishing. Understanding the response of Pst to heat stress is crucial for determining disease risk and the need for fungicide applications to manage stripe rust. This study examines the response of 17 Pst isolates collected in Kansas between 2010-2023. Isolate response to heat stress was investigated by exposing inoculated plants to periods of heat stress (7 days at 22-35°C) under controlled conditions. The latent period and disease progress of Pst infections were compared with plants that had remained in a favorable environment (12-20°C). Results identified that contemporary Pst isolates (2017-2023) had significantly shorter latent periods (13.3 vs. 18.6 days, p< 0.0001) and faster rates of disease progress (p< 0.0034) following heat stress than historical isolates (2010-2016). These results will inform the development of disease forecasting models used to evaluate the risk of stripe rust in the Great Plains region of North America.