Source: Kiersten Wise, Purdue University
Fusarium head blight, or scab, is present in many commercial fields in central and northern Indiana. Incidence and severity vary from field to field, and many fields that appear to look healthy from the road still have low to moderate levels of head blight in the field. Incidence (number of infected heads) ranges from 5-60 percent or higher in areas of central and northern Indiana. Severity (amount of infection per head) ranges from 7-40 percent in these areas. The Fusarium Head blight risk model indicated that risk of infection was moderate in areas of northern Indiana during flowering, and warm, humid conditions after flowering may have allowed initial infections to progress throughout the head.
Fusarium head blight levels were much lower in southern Indiana this year, and many fields have low incidence and severity of the disease. Scouting reports from southern counties indicate that fields with late-flowering varieties did have higher levels of the disease.
Growers should be prepared to deal with DON, or vomitoxin, in fields infected with Fusarium head blight, and should scout fields now to determine the presence and level of the disease in each field. If the disease is present, increasing the fan speed on the combine at harvest can blow out the lighter scabby kernels, which contain most of the DON.
The new Purdue Extension publication Diseases of Wheat: Fusarium Head Blight (Head Scab) is available online here. This publication includes information on prevention and management of the disease, as well as information on DON advisory levels for animal feed. The publication also lists laboratories in Indiana that conduct mycotoxin testing on wheat.