Wheat plot tours (Figure 1) continued this week in western Nebraska. Varying levels of diseases were present at all locations. At the UNL Henry J. Stumpf Wheat Center in Perkins County on June 19, the predominant diseases at moderate to high levels were bacterial leaf streak (Figure 2) and leaf rust (Figure 3). Fusarium head blight (Figure 4) was also at this location and at the West Central Research and Extension Center near North Platte in Lincoln County on June 18, but at low levels.

At the High Plains Ag Lab near Sidney in Cheyenne County on June 21, there were trace levels of leaf rust and low levels of bacterial leaf streak. Plots in a grower’s field in Deuel County on June 21 had low levels of fungal leaf spots (tan spot and Septoria leaf blotch) and trace levels of take-all (Figure 5).

On June 21, a follow-up disease survey was conducted in Deuel and Garden counties in the southern Panhandle. A wheat field in Deuel County that had severe wheat streak mosaic symptoms in May (see May 18 Wheat Disease Update) had prematurely dried down (Figure 6). In Garden County, one field on the survey route had moderate to severe wheat streak mosaic (Figure 7).

Management

It is too late in the growing season to apply a fungicide to control fungal diseases (leaf rust, fungal leaf spots, Fusarium head blight). Bacterial leaf streak, wheat streak mosaic, and take-all cannot be controlled once they occur. In future cropping seasons, losses caused by these diseases can be reduced by

• choosing resistant or tolerant varieties,
• controlling volunteer wheat before planting in the fall (wheat streak mosaic),
• rotating crops (take-all, fungal leaf spots, Fusarium head blight) and
• applying a fungicide during the growing season (leaf rust, fungal leaf spots, Fusarium head blight).