From Gary Bergstrom, Extension Plant Pathologist, Cornell University
Much of the winter wheat and barley in New York State has initiated flowering in the last few days and the remainder of fields are likely to flower over the next week. So the next week remains critical for farmers making fungicide spray decisions for suppression of Fusarium head blight (FHB) and protection of flag leaves from foliar diseases. The triazole products Caramba and Prosaro are the most effective fungicides for suppression of FHB and deoxynivalenol (DON) toxin contamination when applied at wheat flowering (emergence of anthers on heads) or at full head emergence in barley (anthers begin to appear on barley before heads emerge from the boot). A flowering application of triazole fungicide should be based on Fusarium head blight (FHB) risk as well as the risks of powdery mildew, rust, and fungal leaf blotches in the upper canopy based on scouting of individual fields. There is an application window of approximately 5-6 days from the beginning of flowering in which reasonable FHB suppression can be expected. Fungicide products containing strobilurins should not be applied to headed wheat or barley as they may result in increased levels of DON in grain. So far the risk of FHB epidemics forecast by the model has remained low through the early flowering period. And the forecast for precipitation remains low for the next few days. But I urge growers to check the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/) and your local weather forecast frequently as your crop approaches flowering. We will consider the risk of FHB infection of spring wheat and barley in New York in a few more weeks.
