Watch for Leaf Rust on Winter Wheat By Laura Sweets

Leaf Rust

Reports of leaf rust on winter wheat in Arkansas have been filtering into the state for the last few weeks. In fact a recent report from Gene Milus, Plant Pathologist at the University of Arkansas, indicates the leaf rust in southwest Arkansas is at very high levels in fields in which the wheat is at the Feekes 5.0 stage of growth.

So far I have not seen this disease on winter wheat in Missouri, and have not received any reports that it has been found in the state. However, it would certainly be wise to scout fields looking for symptoms of leaf rust.

Leaf rust starts as small yellow to light-green flecks on the upper leaf surfaces. These flecks develop into the small, circular to oval-shaped, orange-red pustules characteristic of leaf rust.

As fields are being scouted for leaf rust, it would also be wise to look for septoria leaf blotch on the lower leaves of wheat plants. Look for light yellow flecks or streaks on the lowest leaves. These flecks expand into yellow to reddish-brown, irregularly shaped blotches. Dark brown specks (fruiting bodies or pycnidia of the causal fungus) may be scattered within the centers of mature lesions.

Now is the time to be scouting fields to determine which leaf diseases are present, as well as the level of their severity. It would be unusual for foliar fungicides to be applied this early in the season, but knowing what is showing up and the incidence and severity of these diseases is crucial in making management decisions later in the season.

Laura Sweets Ag Ext-Plant Sciences 573-884-7307