From Gary Bergstrom, Extension Plant Pathologist, Cornell University
Winter wheat and barley in New York State are now past the flowering and early post-flowering stages so fungicide applications are no longer advised on winter cereals. Attention now turns to spring wheat and especially to spring malting barley crops some of which have emerged from the boot and have begun flowering. The next 10 days will be critical for farmers making fungicide spray decisions for suppression of Fusarium head blight (FHB) and protection of flag leaves from foliar diseases in spring cereals. 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. The current risk of FHB epidemics is moderate to high for spring wheat and barley over much of the state; that risk could remain high if warm, humid conditions with frequent rainfall continue through this week. Check the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/) and your local weather forecast frequently as your crop approaches flowering. FHB symptoms are beginning to appear in winter cereals so this is an excellent time to scout your winter cereal fields to assess FHB incidence and to identify fields that may be at higher risk for DON toxin contamination.
