In your haste to prepare a seed bed for your corn and get it planted, have you been ignoring your wheat crop. For those of you who did not get any wheat planted last year because of the late harvest, wheat may be one worry that you can ignore this year. But for those with a wheat crop coming on, the 2010 weather conditions may not only be beneficial to the wheat crop but also to the fungal invaders that may be lurking.

Foliar diseases may be present in wheat and a good scouting effort will help determine whether you have escaped them to date, or if not, your scouting will help identify potential rescue treatments. Ohio State University agronomists Pierce Paul and Dennis Mills report powdery mildew and septoria leaf blotch are beginning to appear in the Eastern Cornbelt. University of Missouri agronomist Laura Sweets reports the Western Cornbelt is also seeing those, along with tan spot, leaf, stripe, and stem rusts. If you are somewhere in between, you may have some of those fungal problems or even others if you have not yet checked.

The Ohio specialists say powdery mildew is important in May and early June in mild seasons with high relative humidity, and that has been one of the reasons that the fungus has spread so rapidly. They are urging wheat growers to scout fields with varieties that are susceptible to those diseases because of the potential for yield loss. They report, “Research has shown that if disease affects the upper two leaves by heading, yield losses can be as high as 25% on susceptible varieties.”

The Missouri specialist is also warning about yield losses with some diseases, “Leaf rust, stripe rust and Septoria leaf blight are the three most likely to cause losses on soft red winter wheat grown in Missouri. Powdery mildew can be a problem on hard red winter wheat and, under the correct environmental conditions, may also cause losses on soft red winter wheat.”

So how do you do a good job of scouting your wheat to determine if a problem exists? OSU agronomists Paul and Mills suggest, “Scout fields by pulling about 50 individual tillers randomly from throughout the field and look for the small white pustules on the lower leaves and leaf sheaths. Evaluate individual tillers by looking at the top (flag) leaf, then the second leaf. One percent of the leaf area (about 2-3 mildew pustules) on the second leaf between growth stage 8 (flag leaf emergence) and 10 (boot) is the threshold level for applying a fungicide. By the time the second leaf becomes infected, the lower leaves generally have a lot of mildew on them. Fields that needs a fungicide application will have lots of powdery mildew in the lower canopy, but mildew becomes an economic problem only if the disease advances to the upper leaves before flowering.”

Do you have resistant varieties of wheat? Paul and Mills say foliar disease management means that fungicides may not be needed when resistant varieties are grown. Match your wheat variety to this list of resistant varieties. An updated list of fungicides registered for wheat disease management can be found on the field crops disease web site.

If you have found fungus in your wheat, it likely came from residue in the field, says MO agronomist Sweets. And she says disease problems are worst when a field is planted back into the residue of the last crop with the disease. However, the rust fungi do not survive in infested residue, but are carried in on windstorms from southern states.

A wheat fungus management program designed by Sweets has several actions to take before you get to the bottom of the list with a brief discussion of foliar fungicides. Ahead of that preventative action are scouting, use of resistant varieties, rotation with other crops, manage the residue in the field, maintain good plant vigor, control volunteer wheat, and use the fungicides if warranted.

Spring environmental conditions have been conducive for the development of fungal problems in wheat that is beginning to grow rapidly with the help of good sun and moisture. There are a variety of foliar diseases that may be present in wheat. Preventative measures include the use of resistant varieties, crop rotation, a good fertility program, and finally with the use of foliar fungicides.

Source: Stu Ellis, University of Illinois