Our area is at high risk for scab (Fusarium head blight) this year. If infected, all or part of the head will have a white, bleached appearance. Kernels may be absent or shriveled and shrunken. Scab occurs when wet conditions and moderate temperatures are present during flowering and early grain fill. One concern when scab is present is the production of mycotoxins. Non-ruminant animals, like pigs, cannot tolerate grain infected with mycotoxins in their diet. Ruminant animals, like cattle and sheep, are more tolerant of low concentrations.
Be cautious when saving seed wheat from a field showing signs of scab. The fungi that causes scab will remain in the seed and can cause problems in the following crop. Crop rotation and residue management are effective ways to reduce the occurrence of scab. The disease occurs more frequently in wheat planted into corn, grain sorghum or wheat residue.
To determine the effect the disease will have on yield, count the number of heads in a square foot. Multiply that by 43,560 square feet per acre. Count the number of kernels per head on several heads and take the average. Multiply it by the number of heads per acre to find the number of kernels per acre. On average, there are 15,500 kernels per pound in soft red winter wheat. If the wheat kernels are small use a larger number, if kernels are large, use a smaller number. Divide the number of kernels per acre by the number of kernels per pound. Divide by 60 pounds per bushel to determine the bushels per acre. Estimate the yield in several places within the field to find a representative yield for the field.
For more information, contact Valerie Tate, agronomy specialist for the University of Missouri Extension at email@example.com or at 660-895-5123. MU Extension programs are open to all.
Valerie Tate is an agronomy specialist for the University of Missouri Extension.