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Stripe Rust Update, June 2, 2022

Posted by jason.sprott | June 3, 2022

Xianming Chen

Stripe rust in the Palouse Region

Yesterday, I was checking fields in the Palouse region (Whitman County, WA and Latah County, ID). Winter wheat ranged from Feekes 7 to Feekes 10, and spring wheat ranged from Feekes 2 to Feekes 5.  Stripe rust was severe on low leaves (Figure 1) and reached top leaves (Figure 2) of winter wheat and started showing up on spring wheat in all our experimental fields around Pullman, which were artificially inoculated in April.  In contrast, stripe rust was hardly found in breeding nurseries and was not found in any of checked commercial fields.

Severe stripe rust on lower leaves in artificially inoculated winter wheat nurseries near Pullman (Whitman Co.) WA on June 1, 2022

Figure 1. Severe stripe rust on lower leaves in artificially inoculated winter wheat nurseries near Pullman (Whitman Co.) WA on June 1, 2022

Stripe rust reached top leaves in artificially inoculated winter wheat nurseries near Pullman (Whitman Co.), WA on June 1, 2022

Figure 2.  Stripe rust reached top leaves in artificially inoculated winter wheat nurseries near Pullman (Whitman Co.), WA on June 1, 2022

Recommendations for the eastern Pacific Northwest

As the relatively cool temperature and high moisture conditions occurred in May and forecast for the first half month of June are favorable for stripe rust infection and development, and winter wheat crop reaches the heading and flowering stages in some regions, it is critical to check fields for stripe rust.  If active rust pustules are found, fungicide should be applied before the incidence (number of plants having rust) or severity (infected leaf areas) reaches 5%.  In general, fields planted with susceptible or moderately susceptible varieties of winter wheat (stripe rust ratings 6-9) should be sprayed with fungicide before flowering.  For spring wheat, fungicide application is recommended for fields planted with susceptible and moderately susceptible varieties (stripe rust ratings 6-9) at the herbicide application time.

Stripe rust in the country

So far, stripe rust has been reported on wheat in Louisiana, Texas, Washington, Oregon, Georgia, California, Oklahoma, and Maryland and on triticale in California. Barley stripe rust has been reported in Washington and California.

2 thoughts on "Stripe Rust Update, June 2, 2022"

  1. Nick Haugerud says:

    Sripe rust was found on ‘stingray’ north of Colfax. Is that consistant with what you are seeing in your plots?

  2. Hi, Nick:

    Thank you for letting us know stripe rust on Stingray. This is expected based on our data in 2020. Although Stingray was highly resistant in our experimental fields around Pullman, it 40% stripe rust severity at Lind that year. Our greenhouse data showed that Stingray has a moderate level of high-temperature adult-plant resistance, which may not work to its best protection potential under the recent cool temperatures. If the rust pustules are actively producing spores (orange powder), consider spray with fungicide. If you have questions, please feel free to call me (Office 509-335-8086; Cell 509-432-5852).

    Best wishes,

    Xianming Chen
    Research Plant Pathologist
    USDA-ARS
    1222 ITB Johnson Hall
    Washington State University
    Pullman, WA 99164-1222
    Phone: 509-335-8086
    Fax: 509-335-9581
    E-mail: xianming.chen@usda.gov
    xianming@wsu.edu

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