There have been a few reports of virus-like symptoms on winter wheat so far this spring. See last month’s issue of the Integrated Pest and Crop Management Newsletter for more detailed information on the common virus diseases of winter wheat in Missouri.

There have also been a few reports of leaf rust and stripe rust on wheat in the southern United States. It is a little early for these diseases to be showing in Missouri, but with the recent periods of wet weather, it would be wise to begin scouting wheat for leaf rust, stripe rust and Septoria leaf blotch.

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.

Stripe rust may develop earlier in the season than leaf rust. The pustules of stripe rust are yellow to yellowish-red, and occur in obvious stripes or streaks running lengthwise on the wheat leaves.

Septoria leaf blotch may begin as 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