From Gary Bergstrom – Extension Plant Pathologist – Cornell University
The previously consistent forecast of ‘low’ risk of Fusarium head blight is now changing to ‘moderate’ or even ‘high’ risk in several locations in New York State following rains this week, with more rain forecast in the days ahead. While nearly all winter barley and most winter winter fields have flowered and are beyond the growth stage for fungicide application, some late planted winter wheat has just begun flowering or is about to. 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). There is an application window of approximately 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. Leaf rust has been observed on wheat in northwestern New York and should be expected in other parts of the state as well. Triazole applications at flowering should provide adequate protection against early developing rust, powdery mildew, and fungal leaf blotches on flag leaves. Check the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/) and your local weather forecast frequently. I will also comment on conditions later this month as we approach flowering of spring cereals.
