Early wheat crop in area highly susceptible to destructive fungi
Small Grains Pathologist
North Carolina State University
NORTHEASTERN N.C. – The following counties have medium to high ‘scab risk’ for wheat flowering this week: Pamlico, Craven, Beaufort, Washington, Tyrrell, Hyde, Dare, Chowan, Pasquotank, Perquimans, Camden, and Gates
The zone of high risk will likely expand over the next several days, as we get more rain.
Estimates are that as much as 65 percent of the wheat north of the Albemarle is flowering now and over the next week or so. Flowering is a window, not a moment, so the vulnerability of a field extends over the period that both primary and secondary tillers are flowering. Wheat heads are vulnerable when they extrude their anthers and for about seven days after anther extrusion.
Across the state, about 80 percent of our wheat acres are susceptible to scab, which is a destructive disease caused by the Fusarium fungi. Wheat heads and kernels display a scabby appearance caused by tufted outgrowths.
Two things growers and their advisors may not know:
Ideal timing for scab reduction by a fungicide application is early to mid-flowering — when many anthers are out but not yet wilted. However, if that is not possible, a fungicide application up to a week later should be nearly as effective for scab reduction. Applications before flowering are not effective against scab.
Strobilurin-containing products should NOT be applied after Feekes 9 (flag leaf just fully emerged). The most effective scab-targeted fungicides are Prosaro, Caramba, and Proline.
Scab risk is based on favorable relative humidity over the 14 days prior to assessment date. For example, wheat flowering on May 4, relative humidity from April 19 to May 3 determines the risk.