Alyssa Koehler, Extension Field Crops Pathologist; akoehler@udel.edu
Most barley is wrapping up heading. Over the past few days wheat heads have started to become visible. The forecast looks dry over the next week, which is good for limiting FHB pressure. Most of the region is currently at low risk in the Fusarium Risk Tool, with pockets of medium to high risk right at the coastline (Figure 1).
If you are planning for wheat fungicide application, scout frequently and apply when wheat is flowering (Feekes 10.5.1). When we have colder nights, like this week, it can sometimes be quite a few days from when heads become visible until flowering actually begins. Look for yellow anthers in the center of the wheat head to signal the start of flowering (Figure 2). Once wheat is flowering, fungicides are most effective when applied within a 4-5 day window. Anthers can remain attached after flowering, but become a pale white. Fungicide products should be applied at the manufacturers recommended rate with nozzles angled 30-45° from horizontal (30 degrees is better than 45). Nozzles angled both forward and backward or twinjet nozzles that spray in two directions give better contact with the head and increase fungicide efficacy. For ground sprays, fungicides should be applied in at least 10-15 gallons of water per acre; aerial applications are recommended at 5 gallons per acre.
Figure 1. FHB Risk Model for April 28, 2022 (wheatscab.psu.edu)
Figure 2. Wheat at beginning flowering (Feekes 10.5.1) with yellow anthers at the center of the head