Management of Fusarium Head Blight of Wheat: Are "Premium" Fungicides Needed on Resistant Varieties?

Fusarium head blight (FHB; a.k.a. “scab”) is the most important disease of wheat in Kentucky. The fungus that causes this disease (Fusarium graminearum) is always present every year, surviving mostly on corn residue. The greatest problem associated with FHB is the reduction in grain quality. The FHB fungus will produce a toxin known as deoxynivalenol (DON) that contaminates grain. When elevators detect grain with at least 2 ppm DON contamination, severe dockage can be applied (or in severe cases, outright rejection of grain may occur). Severely- infected grain may also have low test weight, which additional dockage can be applied. For sustainable wheat production in Kentucky, it is important to continue to seek economical, but effective, methods of managing FHB and DON. Currently, the fungicide “toolbox” for managing FHB is bigger than it ever has been before, with additional new fungicide products to be submitted for registration within the next couple of years (from BASF and Bayer CropScience). The current products available to manage FHB include Caramba, Miravis Ace, Prosaro, and tebuconazole products (Folicur and others). As shown with previous research, under high disease pressure, fungicides alone may not be effective enough to protect against losses, and the greatest level of disease control comes from integrating the use of resistant varieties and effective fungicides. Even with new “premium” fungicide products available with greater efficacy, it is still true that their use on resistant varieties will result in greater overall disease control vs. using these “premium” products on susceptible varieties. As observed under high disease-pressure, mist-irrigated field research trials, FHB-resistant varieties really stand out to be the most important and first FHB management practice that wheat farmers must utilize. For the most-resistant wheat varieties available, do they require a “premium” fungicide or will a tebuconazole product be adequate enough to use on these most resistant varieties? This proposal will evaluate the effect of different fungicide products on a set of wheat varieties that vary in their susceptibility to FHB. The fungicide products evaluated will include Caramba, Miravis Ace, Prosaro, tebuconzole, and two new experimental fungicides that will be submitted for registration within the next couple of years (from BASF and Bayer CropScience). Our hypothesis is that on the most resistant wheat varieties, overall control of FHB achieved with a “premium” product will be similar to that achieved with tebuconazole, but that on susceptible varieties, the overall control of FHB will be superior with “premium” products vs. tebuconazole. These field research trials will be conducted under a high disease pressure environment (corn stubble on soil surface and mist-irrigation utilized to keep wheat heads wheat).