The wheat expected to flower over weekend in southern Indiana is at moderate to high risk for Fusarium head blight (FHB), or scab, development (Figure 1).
The FHB risk assessment tool (here) is predicting that wheat that will soon flower (Feekes 10.5.1) in southern Indiana will be at moderate to high risk for FHB, depending on variety susceptibility.
If varieties susceptible to FHB have been planted, or farmers are worried about the risk of FHB development, they may want to consider a fungicide application at early flowering for suppression of FHB.
Indiana research indicates that applications of the fungicides Prosaro and Caramba are most effective at managing FHB if they are applied at Feekes 10.5.1. Other products are available, but may not be as effective.
Fungicides that have a strobilurin mode of action are not labeled for Fusarium head blight suppression.
The recent rains have delayed some fungicide applications, or may prevent applications from occurring precisely at Feekes 10.5.1. Research conducted at Purdue and other institutions indicates that fungicide applications can occur after flowering and still suppress FHB and the associated mycotoxin deoxynivalenol (DON; vomitoxin).
For more information please see Purdue Extension Bulletin BP:145-W, Revised Fungicide Spray Recommendations for Fusarium Head Blight. Although some level of efficacy may be obtained for applications occurring a few days after flowering, fungicide applications should occur as close to Feekes 10.5.1 as possible for best results.