Although many wheat fields appear to be a week to 10 days or more away from harvest maturity, those in particularly dry areas are progressing quickly. A few fields in south-central South Dakota have already reached maturity, but as they began to harvest the crop, the producers quickly learned that the test weight was very low. One field produced wheat that weighed 47 lbs. /Bu. As test weights drop below 60 lbs. /Bu, discounts begin to mount. The lowest test weight that wheat can be marketed at grain elevators is 50 lbs. /Bu., with discounts in the neighborhood of $0.70/Bu at that level.
There are several potential reasons for wheat being low in test weight, including drought, root and crown rots, viral diseases, fungal or bacterial foliar diseases, scab, etc. It is difficult to determine the test weight of a wheat crop until it is mature and harvested, but the presence of a substantial percentage of shriveled kernels should raise a red flag.
If wheat is low in test weight, one strategy may be to open the sieves on the combine and turn up the wind in hopes of blowing some of the lighter, shriveled kernels out the back. Harvested wheat that is light might also be cleaned aggressively in an attempt to gain test weight. If the majority of the kernels are lighter and shriveled, the potential of gaining much test weight by is likely to be limited. If using either of these strategies, producers would need to compare the benefit of gaining test weight against the yield loss due to blowing the light seeds out the back of the combine or aggressive cleaning.
The remaining options are to harvest the wheat to sell as feed wheat at a significant discount, or harvest as hay. Unfortunately, crop insurance may not offer substantial coverage for wheat that is low in test weight. The adjustment for light wheat doesn’t reach significant levels until the bushel weight drops into the low 40 lb. /Bu range. If producers suspect they may have wheat that is low in test weight, they should contact their crop insurance agent to evaluate their options before cutting for hay or harvesting the crop as grain. If considering harvesting the crop as hay, check herbicide, fungicide or insecticide labels of any products that have been applied for the pre-harvest interval or if the label allows harvesting as hay.