Case Details
Powdery mildew in wheat
Submitted by Mike Rankin on 5/15/2000
Field is one leaf away from flag emergence. Undercanopy is loaded with powdery mildew (both leaves and stems) but top of canopy still looks ok. Given the price of wheat, etc., is best approach to act now with fungicide, wait for flag emergence, or do nothing regardless? I always have a tough time knowing which way to go when it comes to fungicides for wheat. Too much depends on unknown weather conditions.
Reply by Craig R. Grau on 5/18/2000
The problem is powdery mildew. This appears to be more severe than usually observed. An applicaton of Tilt fungicide would likey result in a yield increase. The price of wheat may be a limitation to many growers. Fields that have received high rates of N will likely have more powedery mildew than less intensely managed fields. Tilt must be applied by flag-leaf stage before ligule of flag leaf emerges. Only one application per year is allowed by the label. Leaf rust of wheat is severe in states to the south of Wisconsin. I have not observed leaf rust but inoculum is likely here and a matter of time before symptoms appear. Tilt will protect against leaf rust. We have postively detected soilborne mosaic and wheat spindle streak virus in Racine county. Both viruses are transmitted by a soil inhabiting fungus. The fungus itself is not pathogenic but it transmits the virus via the roots. Early planted winter wheat fields are more likely to have a problem than fields planted in late September or early October. Soilborne mosaic virus is a significant problem in Oklahoma, Kansas and Nebraska. I suspect there are differences in how winter wheat varieties react to both viruses but I do not have information at this time.
