From Gary Bergstrom, Extension Plant Pathologist, Cornell University
Most, but not all, spring barley and wheat fields in New York State are now past the flowering and early post-flowering stages. This week remains critical for farmers making fungicide spray decisions for suppression of Fusarium head blight (FHB) and protection of flag leaves from foliar diseases in late flowering 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 low to moderate for spring wheat and barley over much of the state but precipitation patterns have been highly variable across the state. Check the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/) and your local weather forecast frequently as your crop approaches flowering. 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.
