Delaware and parts of Maryland are now in a moderate to high risk level for scab. I expect this risk to continue through the weekend with heavy rains expected tonight and Friday. Fields entering flowering are at the highest risk for scab. The best fungicides for scab are Prosaro, Caramba, and Proline. Do not apply products containing a strobilurin (e.g. Aproach Prima, Quilt, Stratego, Headline, Quadris, etc.) as strobilurins have been associated with elevated DON levels when applied to the head and scab occurs. There is a 5-6 day window after the majority of a field is flowering and conducive weather occurs to make a fungicide application and maximize efficacy. Ground rigs should have nozzles angled at least 15 degrees in the forward direction and apply at least 10 gallons per acre, with 15-20 being optimal. Aerial applicators should apply at 5 gallons per acre. Shoot for 300 to 350 micron droplet size. Prosaro, Caramba, and Proline will control foliar diseases.
--Nathan Kleczewski, Extension Specialist, University of Delaware
For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu