Wheat harvest is just around the corner. Based on the cool, wet weather, there are indications that we may see higher than normal levels of fusarium head blight (FHB) in certain areas. While at this stage we cannot eliminate the problem there are thing that can be done to limit the impact of FHB on the harvested crop. Fusarium can be a significant grading factor and the associated discounts (which can be very significant) are meant to allow wheat to compete with corn in the feed trade.
The key at harvest is to try and prevent infected kernels from going into storage. Here are a few suggestions:
- Scout each field to determine the rate of infection between fields as well as patterns within each field such as low areas or fungicide treated versus untreated area. If there are differences consider harvesting them separately.
- Use higher fan speeds to try and blow infected kernels out the back of the combine. The infected kernels tend to be smaller, lighter and more shrunken than healthy kernels. Research at University of Guelph – Ridgetown found there was a tenfold decrease in Fusarium-damaged kernels in the grain sample when fan speeds were operated on a high setting. However, this strategy of higher fan speeds can result in healthy kernels also going out the back. The same study at Ridgetown showed, up to 2 bushels per acre of good kernels were also lost. You may need to decide if you want to trade better grade for a lower yield. As well, higher fan speeds will not remove all the damaged kernels. Later infected kernels may still be plump and not blown out the combine.
- Reducing harvest speed may reduce Fusarium-damaged kernel levels. The slower speed deduces grain volume and allows increased separation of the grain at the fans, removing more of the infected kernels.
- Harvest at slightly higher than normal moisture contents. Target harvest at 18% moisture and then heat dry the grain to at least 14%. This will help limit the development of the disease as moisture fall, but still allow good separation in the combine as higher moisture grain (> 18%) reduces the ability to blow the lighter damaged kernels.
- After harvest, gravity table grain separation can be effective in removing light-weight, damaged kernels. The increased marketability of the cleaned grain may pay for the cost of the clean-out process.
- Dry infected grain going into storage to at least 14% in a heated air dryer. This will stop further disease development. To maintain quality, do not allow the temperature of the grain to reach 60°C (140°F) for any significant length of time.
- Fusarium levels vary between fields as well as within the field. If there are differences, harvest and bin harvested grain separately. This will allow good quality grain to keep marketability as well as manage the poorer quality grain more efficiently.
While FHB can affect both yield and grade, there are steps to take to limit this impact. Some scouting, harvest management and ensuring proper storage can go along way to maintaining grade and profitability.