No. 4 Article 4/April 27, 2012

Stripe Rust of Wheat Update

Stripe rust of wheat has been observed in several southern Illinois counties. In some cases the disease is present only on lower leaves; in others it is present on the flag leaf. It is important that fields in southern Illinois be scouted for stripe rust, as many wheat fields are now heading and beginning to flower (Feekes growth stage 10.5.1).

Considering the growth stage of the wheat, fungicides registered for control of Fusarium head blight (scab), such as Caramba, Prosaro, and tebuconazole products (Folicur and others), would be the ones to apply if needed for protection against stripe rust. In addition to suppressing Fusarium head blight, these products have excellent efficacy against stripe rust, and their labels allow applications during flowering (unlike other products that may not allow applications past the Feekes 10.5 heading stage).

Stripe rust pustules on a wheat leaf. Photo was taken on April 19, 2012, in a wheat field in White County, Illinois.

For wheat growers in central and northern Illinois, it is equally important to scout for stripe rust, as the disease will continue to move northward if favorable weather persists. In general, cool to moderate temperatures (<70°F) favor stripe rust.

Stripe rust symptoms first occur as chlorotic linear streaks on the leaves. Later on, yellow to orange pustules develop in a linear fashion ("stripes") within these chlorotic streaks.--Carl A. Bradley

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