Figure 1. A yellow patch in a wheat field in Saunders County (May 15).	Figure 2. Severe tan spot on lower leaves in a wheat field in Saunders County (May 15).

 

May 16, 2008 

Figure 3. High density of pseudothecia (sexual fruiting structures of the tan spot fungus) on wheat straw in a wheat field in Saunders County (May 15).

On May 14, leaf rust was found in trace levels in the very southern portions of Webster, Nuckolls, and Thayer counties in south central Nebraska. These counties border Kansas. The rust is expected to spread north in the coming weeks. Severity will depend on the weather and cultivar susceptibility. Leaf rust is favored by wet weather, high humidity, and temperatures ranging from 59°F to 72°F. Other diseases observed in Webster, Nuckolls, and Thayer counties were Septoria leaf and glume blotch and powdery mildew. In most cases, disease pressure was minimal.

At the Agricultural Research and Development Center (ARDC) near Mead on May 14, powdery mildew was heavy on the lower leaves and stems in wheat plots with a dense canopy.

Also see this week . . Wheat Fungicide Update Wheat Condition Update

In Saunders County on May 15, yellow patches (Figure 1) were observed in some wheat fields. This yellowing was attributed to nitrogen deficiency. In a field in which wheat was planted into wheat stubble from last year's crop, severe tan spot (Figure 2) was evident on the lower leaves and was spreading to the upper canopy. Density of pseudothecia (sexual fruiting structures of the tan spot fungus) was very high on wheat straw in this field (Figure 3).

A new Extension Circular, Fusarium Head Blight of Wheat, has been posted to the UNL Extension Web site. It can be accessed at: http://www.ianrpubs.unl.edu/sendIt/ec1896.pdf.

Jennifer Rees
Extension Educator
Dewey Lienemann
Extension Educator
Keith Glewen
Extension Educator
Stephen Wegulo
Extension Plant Pathologist