FHB Update from NY, 05/22/19

Some winter malting barley in New York is beginning to emerge from the boot and this is a critical time to consider a fungicide application. The Fusarium Risk Assessment Map (http://www.wheatscab.psu.edu/riskTool.html) indicates a moderate to high risk of Fusarium head blight (FHB) for several areas of New York. Maximal suppression of FHB and grain contamination by deoxynivalenol (DON) mycotoxin results when fully emerged heads of winter malting barley are sprayed with full label rates of Caramba or Prosaro fungicides. A heads emerged spray with these triazole fungicides also helps protect upper leaves against fungal leaf blotches, powdery mildew, and rust. Foliar sprays of Caramba or Prosaro up to seven days after head emergence may still result in significant FHB and DON suppression. Unfortunately, Miravis Ace, a new fungicide product with activity against FHB, will not receive NYSDEC label approval in time for use on small grain crops this season. Fungicide products containing strobilurins should not be applied to headed wheat or barley as they may result in increased levels of DON in grain.

Winter wheat is generally a week or more behind in development from winter barley planted on the same fall date. Winter wheat in New York varies from stem elongation to flag leaf visible stages. We should reach the critical fungicide application window for winter wheat over the next two weeks. The triazole products Caramba and Prosaro are the most effective fungicides for suppression of FHB and DON contamination when applied at flowering (emergence of yellow anthers on heads). A flowering application of triazole fungicide should be based on Fusarium head blight (FHB) risk as well as the risks of powdery mildew, rusts, and fungal leaf blotches in the upper canopy based on scouting of individual fields. There is an application window of approximately 7 days from the beginning of flowering in which reasonable FHB suppression can be expected. Check the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/) and your local weather forecast frequently as your winter wheat crop approaches heading and flowering.

--Gary Bergstrom, Extension Plant Pathologist, Cornell University

For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu

For the latest news and updates from the U.S. Wheat & Barley Scab Initiative, go to https://www.scabusa.org