Integration of cultivar resistance and fungicide application for control of wheat stripe rust

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat. The disease is mainly controlled by growing resistant cultivars and applying fungicides when necessary. To determine potential yield loss and fungicide response, major cultivars grown in the US Pacific Northwest and susceptible checks were tested in complete split-block design experiments. From 2002 to 2012, stripe rust caused yield losses ranging from 18% to more than 90% and from 5% to more than 50% with an average of 44% and 33% on susceptible winter and spring wheat checks, respectively. Without fungicide application, the commercially grown cultivars with various levels of stripe rust resistance could reduce potential yield losses to 2–21%, with an average of 8% for winter wheat, and to 0–27% with an average of 13% for spring wheat. Significant or insignificant effects of fungicide applications on yield increase were determined for each cultivar, and the results were used to guide stripe rust management by selecting resistant cultivars to grow and appropriately applying fungicides under different levels of stripe rust epidemic. The results should be useful for developing wheat cultivars with high durable resistance, and for improving chemical control in order to minimize yield losses and maximize profits while protecting the environment by reducing use of fungicides.