• Print
• Share

Harvest and Storage Strategies to Minimize Fusarium

If you are harvesting wheat that has some Fusarium infected kernels there are some strategies that will eliminate many of these in the field and arrest the further development of this disease in storage. There is no rescue treatment available to combat the Fusarium that exists now in the wheat fields. Careful harvesting, drying and storage strategies are the farmers' best way to maximize grain quality. Following these suggestions will eliminate most of the infected kernels and stop the further spread of Fusarium infection in the harvested wheat.

• Harvest early, at 18% moisture content or higher
• Use high fan speeds to blow out infected kernels
• immediately dry infected grain over 16% M.C. in a heated air dryer to stop the spread of infection

When to Harvest

Harvest should not begin above 18% moisture content if significant Fusarium is present. High moisture grain reduces the ability to blow out the lighter Fusarium-damaged kernels.

Harvest Speed

Reducing your combine travel speed when harvesting may reduce Fusarium levels. This slower combining speed allows for increased separation of the grain by allowing the increased air blast time to separate the good kernels from the infected kernels.

Fan Speed

Many of the Fusarium infected kernels are small, shrunken and lighter than sound kernels. It is possible to blow a large proportion of these Fusarium damaged kernels out the back of the combine by increasing the fan speed to deliver an air blast above normal ranges.

Testing at Ridgetown in 1996 found that high fan speeds blew out a significant percentage of tombstone kernels caused by primary Fusarium infection. There was a tenfold decrease in Fusarium damaged kernels in the grain sample when fan speeds were operated to deliver maximum air blast. Operating cleaning fans at these high speeds causes an additional loss of good kernels, up to 2 bushels per acre (0.13 t/ha). This small yield reduction is insignificant if the crop can be made marketable, rather than being downgraded to feed, sample or salvage. To adjust your own combine, start at maximum fan speed and check the harvest sample. Reduce the fan speed if necessary and again evaluate your harvest sample for Fusarium Damaged Kernels (FDK). Table 1 shows the effect of different fan speeds on wheat yields.

Case International 1644, Harus Wheat, Essex County, July 17, 1996.
Travel speed 4.2 mph. Rotor speed 880 rpm.
Source: Dr. Art Schaafsma, University of Guelph, Ridgetown College, 1996.

Chaffer Setting

Consider adjusting the cleaning sieves (chaffer) to a more wide-open setting. This directs the air blast vertically, slowing the rearward movement of the grain mass and aiding cleaning and separation. Caution must be used to keep wheat heads and straw pieces out of the grain sample if the chaffer is opened.

Maximum Drying Temperatures

A number of different types of dryers can be used to dry wheat with heated air. To maintain milling quality you should follow the recommendation on Table 2 Maximum Recommended Air Temperatures for Drying Milling Wheat. The baking quality of wheat is damaged if the temperature of the grain reaches 60oC (140oF) for any significant length of time. The kernel temperature of the grain is not the same as the plenum temperature of the drier. Kernel temperature should be measured by putting a sample of grain in a steel can and placing the thermometer in the centre of the sample. When heated air dryers are used, it is a worthwhile precaution to have samples evaluated to ensure the dried grain meets market standards.

¹Copyright: Farm Drying of Wheat, Canadian Grain Commission, Sept 1992
²Wilcke, William F., Hellevang, Kenneth J. Wheat and Barley Drying, FS-5949-GO, 1992. University of Minnesota, Extension Service