Scabby wheat heads
Print
EmailEditor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Fusarium head blight (head scab) is making more of a showing than the national head scab model predicted and more than this observer suggested only days ago. Weather patterns in some parts of the state led one to suspect that there would be some “hot spots.” Currently, however, scabby heads are appearing on a larger geographical scale.
Fields
that are now included on the suspect list are those that began
flowering on or after Memorial Day (May 31), and those that received
abundant localized showers since the time of heading.
An occasional scabby head is usually not a concern. Nonetheless, if the
incidence of scab is more than approximately one or two percent (one per
three foot of row), there is justifiable concern, especially for soft
white wheat. However, even at this level it does not necessarily mean
that it will lead to excessive DON levels.
Fields that received a fungicide treatment may still hold scabby heads. Albeit, it is probably reasonable to expect the scab incidence (number of scabby heads) and severity (the amount of the head showing evidence of scab) to be reduced by half or more.
There may be some confusion when looking at light colored heads. Where there is a single, completely bleached, barren head, the cause is more likely due to early damage to the tiller by an insect or disease. Where there is a cluster of bleached heads, the cause may be a root disease such as take-all. Scabby heads are usually bi-colored with some florets infected and some not. The best time to assess scab incidence is just as the wheat begins to turn.
