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Submitted by Northern SWW Region on 14, May 2021
Winter malting barley in New York ranges in development from boot stage to heads fully emerged. The Fusarium Risk Assessment Map (www.wheatscab.psu.edu) today indicates risk of Fusarium head blight (FHB) ranging from low to severe for FHB susceptible varieties that have fully emerged heads, depending on area of the state. The risk level is expected to decrease for heads emerging next week with a drier forecast for the next several days. Duration of leaf/head wetness is more important for FHB development than is the amount of precipitation. Maximal suppression of FHB and grain contamination by deoxynivalenol (DON) mycotoxin results when fully emerged heads of winter malting barley are sprayed with DMI (FRAC Group 3) containing fungicides Caramba, Prosaro, or Miravis Ace (latter includes FRAC Group 7 fungicide). A heads-emerged spray with these fungicides also protects upper leaves against fungal leaf blotches, powdery mildew, and rusts. Foliar sprays of any of these three produc ts up to seven days after head emergence may still result in significant FHB and DON suppression. Fungicide products containing QoI (FRAC Group 11) fungicides should not be applied to headed wheat or barley as they may result in increased levels of DON in grain. We are currently observing low levels of scald and powdery mildew in winter barley.

Winter wheat in New York ranges in development from flag leaf visible to boot stage. The critical time for an FHB fungicide decision is a week or more ahead. The DMI (FRAC Group 3) containing fungicides Caramba, Prosaro, or Miravis Ace (latter includes a FRAC Group 7 fungicide) 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 these fungicide products 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 and DON suppression can be expected. Powdery mildew is prevalent now in mildew-susceptible varieties. Check the Fusarium Risk Assessment Tool (www.wheatscab.psu.edu) and your local weather forecast frequently as your win ter wheat crop approaches heading and flowering.

--Gary Bergstrom, Extension Plant Pathologist, Cornell University