Stripe Rust Widespread in Southeast and South Central Nebraska
|Figure 1. Low severity of stripe rust on an upper leaf in a field in Thayer County on April 18.||Figure 2. Lower leaves with moderate to high stripe rust severity in a state variety trial in Saline County on April 18.|
April 20, 2012
|Also see Timing Critical to Treating Stripe Rust in Wheat|
A survey of wheat fields in southeast and south central Nebraska on April 18 showed that stripe rust is widespread in this region. Fields were surveyed in seven counties (Saline, Jefferson, Thayer, Nuckols, Webster, Adams, and Clay). Stripe rust was found in all counties and in nearly all fields surveyed. Incidence (percentage of diseased plants) ranged from trace to about 50%. Severity (percentage of leaf area diseased) ranged from low (Figure 1) to high (Figure 2). High severity was observed mostly on lower leaves in “hot spots” in the field and low severity was observed on upper leaves including the leaf immediately below the flag leaf.
Figure 3. A spot of wheat stunted by barley yellow dwarf in a field in Nuckols County on April 18. This field had numerous such spots including some that were large in size.
Environmental conditions (cool temperatures and moisture) during the last one to two weeks have been and continue to be conducive to stripe rust development. Stripe rust can develop and spread rapidly under these conditions. Fields should be scouted regularly for stripe rust and other diseases such as tan spot, Septoria leaf blotch, and powdery mildew. The decision to apply a fungicide should be based on the amount of disease in the field, yield potential, and susceptibility of the variety planted. A list of fungicides for wheat diseases has been compiled by the North Central Regional Committee on Management of Small Grain Diseases (NCERA-184).
Fungicides are most effective if applied when disease levels are still low. With stripe rust already present in many fields, it is recommended that a fungicide with both preventive and curative activity be applied. All fungicides in the table have preventive activity. Fungicides that have good curative (and preventive) activity are those that have an active ingredient (a triazole) that ends in “–zole”.
Other diseases observed during the survey were tan spot, Septoria leaf blotch, powdery mildew, and barley yellow dwarf (Figure 3).
Extension Plant Pathologist