The forecast is currently calling a 20-40% chance of storms in parts of Delaware from Tuesday through Thursday. Most wheat is at Feekes 8-9, some is close to heading. With the rain we had in parts of the region last week, there is a chance that inoculum of FHB is starting to pick up and some additional rain may be all that is needed to release inoculum. Those individuals with fields that were heading late last week may enter flowering during this period. You have a 5 day window to hit for fungicide applications after the start of flowering without a dropoff in DON suppression.. The best fungicides for DON suppression are Prosaro, Caramba, and Proline, but Folicur and Tilt have subtle activity if nothing else is available. Fungicides for FHB suppression will also handle foliar diseases, which have been low in the canopy in most fields.
Do not use fungicides containing a group 11 active ingredient (e.g. Quilt, Aproach Prima, Stratego, Headline, Quadris, etc.) as these fungicides have been associated with increased DON levels when applied to heads. Remember that fungicide use will not get you much more than 42-45% control of DON at best unless they are applied to a moderately resistant variety, in which case 75% control is achievable.
--Nathan Kleczewski, Extension Specialist, University of Delaware
For more details, go to the FHB Risk assessment tool at http://www.wheatscab.psu.edu