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Wheat Leaf Rust Found in North Dakota (07/04/19)

Wheat leaf rust was found at very low levels in winter wheat plots in Cass County

Wheat Leaf Rust Found in North Dakota

Wheat leaf rust was found at very low levels in winter wheat plots in Cass County (Figure 1). As a reminder, wheat rust (leaf, stripe and stem) pathogens do not overwinter in North Dakota (ND). Rust pathogen spores arrive in the state along the ‘Puccinia Pathway”, which means spores are blown into the state from southern states. The greatest amount of yield loss from wheat rusts occurs when rust is reported at early growth stages (tillering and jointing) on a susceptible variety. At later growth stages (heading and beyond), yield loss potential is reduced.

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Scab Risk Update

The recent rain events, prolonged morning dews, and moderate to high humidity have increased scab risk for susceptible varieties in several areas in ND (Figure 2). Areas under moderate to high risk include pockets in northwest ND, northeast ND, and southeast ND. With the given forecast, scab risk will likely stay elevated for these areas. Although growth stage varies in the state, several spring wheat fields will be entering flowering stages soon and several barley fields are heading. As a reminder, the best time to apply a fungicide in wheat and durum is when at least 50% of main stems are at early-flowering, and for barley at least 50% of the main stems are at full-head (spike). Recent research suggests that a fungicide application made within 7 days after early-flowering in wheat or full-head in barley can still provide good scab and DON/VOM suppression.

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Andrew Friskop

Extension Plant Pathology, Cereal Crops

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