Wheat Disease Update: Leaf Rust and Scab Found

Wheat Disease Update: Leaf Rust and Scab Found

Photo of severe leaf rust

Moderate to severe wheat leaf rust

Figure 1. (Left) Severe leaf rust on a flag -1 leaf of a susceptible cultivar in the state variety trial at Havelock Farm in Lincoln on June 3.
Figure 2. (Above) Moderate to severe leaf rust on the flag leaf of a breeding line at Havelock Farm in Lincoln on June 3.

Photo of a low level of leaf rust

Figure 3. A low level of leaf rust in a grower's field in Lancaster County on June 4.

 

June 5, 2009

Photo of fusarium head blight
Figure 4. Fusarium head blight.
Photo of a moderate incidence of head blight
Figure 5. A moderate to high incidence of Fusarium head blight in a grower's wheat field in Lancaster County on June 3.

 

Leaf rust and Fusarium head blight (scab) were found June 3-4 during surveys of a state variety trial, breeding nurseries, and growers' wheat fields in Lancaster and Saunders counties. Leaf rust severity was high on a susceptible cultivar and a breeding line (Figures 1 and 2) at UNL's Havelock Farm in Lincoln, but was at trace to low levels (Figure 3) at the Agricultural Research and Development Center near Mead and in three growers' fields.

Because leaf rust arrived in Nebraska rather late and is at low levels in growers' fields, it is not expected to cause economic yield losses.

Fusarium head blight (Figure 4) was found at moderate to high levels in several areas of a grower's field in Lancaster County (Figure 5). This is the only field where scab was found at significant levels during field surveys conducted the last three weeks in south central and southeastern Nebraska. Other fields had negligible (less than 0.1% incidence) or no scab, likely due to a prolonged period of dry weather before flowering.

Stephen Wegulo
Extension Plant Pathologist