I have been out in several wheat fields recently and have noticed the symptoms of head scab. This is not suprising since our region was at a high risk for developing head scab about a month ago during the warm humid weather we had.
The symptoms of head scab are easiest to see before the wheat turns. Bleached spikelets will be present in an otherwise green head, and with closer examination an orange-pink cast can be seen. Scab is important, not only because it reduces yield, but it reduces the quality and feeding value of the grain. The fungi causing scab may produce toxins (Vomitoxin) in the infected grain which are toxic to livestock and humans. This can result in price reductions or rejection of the grain at the elevator. I have been getting calls if there is anything that can be sprayed at this time. Unfortunately it is too late, at this time for fungicides. Fungicides applications for head scab must be applied at flowering, which was several weeks ago. Applications before or after flowering provide little control. Fungicide applications for control of head scab are not 100% effective, but can reduce levels of toxin to levels that will prevent a price reduction. What can you do during harvest to help the situation? If a field has head scab, harvest it using a high fan speed. This will help clean out the lighter, infected kernels. These kernels are generally higher in vomitoxin. Another option is to attempt to segregate scabby fields from clean ones during harvest.