Late Stripe Rust Continues

Stripe rust on wild grass.

Dr. Xianming Chen (ARS Plant Pathologist) released an updated stripe rust forecast last Monday, April 18, 2022. Consistent with his last update from early March, no stripe rust was found on wheat in their survey of commercial fields in Benton, Columbia, Garfield, and Walla Walla Counties, WA or Umatilla County, OR. Stripe rust was observed on wild grasses at their rust monitoring nurseries at the OSU research center in Hermiston, OR and WSU research center in Central Ferry, WA; however, no stripe rust was observed at the breeding nursery in Walla Walla, WA.

Although early season predictions called for moderate stripe rust for the 2022 growing season, stripe rust continues to develop much later this season than is typical. Consequently, Dr. Chen is not recommending prophylactic application of fungicide with herbicide. Rather, continue scouting fields for the presence of stripe rust and consider fungicide application when 1-5% of plants have active rust (yellow-orange sporulation on leaves). Given the continued late appearance of stripe rust, it’s unlikely that varieties with a rust resistance rating of 1-4 will require fungicide application; however, rust may still develop on those rated 5 and above in the Washington State Crop Improvement Seed Buyer’s Guide and the Variety Selection tool on the Wheat & Small Grains website.I will provide more rust updates as the season progresses and new predictions are released. In the meantime, you can find additional information on stripe rust, including photos showing rust percentage under the Foliar Fungal Diseases in the Disease Resources section of the WSU Wheat and Small Grains website.

Tim Murray.

For questions or comments, contact Tim Murray via email at, via phone at (509) 335-7515, or by following him on Twitter @WSUWheatDoc.