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(left) Figure 1. Leaf rust (above) Figure 2. Barley yellow dwarf (above) |
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| Figure 3. A cultivar susceptible to leaf rust showed a yellow to brown cast |
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| Figure 4. Stripe rust |
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| Figure 5. A field at UNL's Agricultural Research and Development Center exhibits a severe epidemic of stripe rust. |
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| This Saunders County wheat field is severely stunted and heading at a height of approximately 1 foot. |
June 1, 2007
As of May 31, the major diseases in many wheat fields in south central and southeastern Nebraska were leaf rust (Figure 1) and barley yellow dwarf virus (Figure 2).
Fields planted with cultivars susceptible to leaf rust are showing 100% disease incidence (percentage of diseased plants) and more than 70% disease severity (percentage of diseased leaf area) on flag leaves. In Gage County on May 31, a field planted with a cultivar susceptible to leaf rust showed a yellow to brown cast (Figure 3).
Stripe rust (Figure 4) is not showing up in grower's fields as much as leaf rust. However, in a research field at UNL's Agricultural Research and Development Center (ARDC), there is a severe epidemic of the disease on cultivar 2137. In many areas in the field, flag leaves are showing up to 100% chlorosis due to stripe rust (Figure 5).
In Saunders County on May 25, a 10-acre section of a field had severely stunted wheat. Most of the wheat was heading at a height of approximately 1 foot and displayed symptoms of wheat streak mosaic virus (Figure 6).
Many fields are also showing severe symptoms of Septoria leaf blotch especially on the lower leaves.
On June 1, barley yellow dwarf virus, Septoria leaf blotch, and black chaff were confirmed on samples sent to the Plant and Pest Diagnostic Clinic from Perkins County.
Other diseases present in wheat fields include tan spot, powdery mildew and loose smut. White heads due to the stem maggot also have been identified in wheat fields.
For more pictures of wheat diseases observed this season, see the May 11 CropWatch story, Wheat Disease Update: Leaf Rust Confirmed in Nebraska and the May 18 story, Stripe Rust Found, Leaf Rust Widespread in Nebraska Wheat.
Stephen Wegulo
Extension Plant Pathologist, Lincoln
Tamra Jackson
Extension Plant Pathologist, Lincoln
Keith Glewen
Extension Educator, Lincoln
