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Stripe Rust in North Dakota (06/01/17)

The first report of stripe rust for the 2017 growing season was found in winter wheat located in Dunn County (found by Ed Cuskelly – Helena Chemical Company).

Stripe Rust in North Dakota

The first report of stripe rust for the 2017 growing season was found in winter wheat located in Dunn County (found by Ed Cuskelly – Helena Chemical Company). Pustules were found on the oldest leaves located in the lower and middle canopy. The trend of early stripe rust reports continues for the state as the disease was identified on May 23rd in 2016 and June 1st in 2015. Conducive conditions for stripe rust development include cool temperatures and periods of prolonged leaf moisture from morning dews and rain (6 hours or more). Although warm temperatures above 80°F will hinder stripe rust development, field observations have indicated the pathogen may continue to produce viable spores.

Identifying Stripe Rust

Early-season observations of the stripe rust pathogen include yellow-orange spores appearing in segments on infected leaves (Figure 1). Infections that manifest in the middle canopy or upper canopy will have the characteristic linear yellow orange pustule extending longitudinally along the leaf (Figure 2). In both cases, pustules will possess a yellow-orange color differing from the reddish-brown pustules of the leaf rust pathogen (Figure 3). Rust diseases are often first noticed in areas of the field with prolonged periods of moisture including low spots or along shelterbelts.

Next Steps

Make sure to scout fields and have knowledge on the level of resistance in the variety being grown. Stripe rust ratings for both winter wheat and spring wheat can be found in NDSU variety selection guides(A1196-16 ND HRWW and A574-16 ND HRSW). If a moderately resistant or resistant stripe rust variety is being grown, a fungicide application at flag leaf for stripe rust management is not recommended. However, if a susceptible or moderately susceptible variety is being grown and stripe rust has been confirmed in the field, a fungicide application at flag leaf may be recommended especially if conducive conditions are present. Fungicides at tillering (herbicide timing) will protect the leaves that were available at the time of the application, but as the wheat plant continues to grow, the newest leaves are left vulnerable to infection.

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Andrew Friskop

Extension Plant Pathology, Cereal Crops


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