Bob Fanning
Plant Pathology Field Specialist
Reports of ergot continue to come in from around the state, with numerous loads of wheat being rejected at South Dakota elevators. A local seed conditioning facility recently cleaned a few loads of spring wheat which was contaminated with ergot in order to make it marketable. One load of uncleaned wheat contained 0.16% ergot by weight, over 3 times the acceptable level. As stated in a recent column, the USDA Federal Grain Inspection Service grain standard, used by elevators, grades grain as undesirable when the level of ergot exceeds 0.05% by weight. The standard cleaning process, normally conducted to prepare harvested wheat for planting, lowered the level to 0.05% ergot by weight, which is acceptable, and allowed the grower to market the grain. If the standard cleaning process fails to reduce the level of ergot to where it can be accepted, a gravity table may also be used as the ergot bodies are lighter than wheat kernels. The figures below show 500 gram samples of wheat from a different load and the ergot that was removed from each by hand. The standard sample size to assess the ergot content of a load of wheat is 1000 grams, which is about one quart and weighs about two pounds. Although the size and weight of ergot bodies vary, a general guideline is that 10 ergot bodies in a 1000 gram sample is about 0.05% ergot by weight.
Figure 1. 500 gram sample of spring wheat before cleaning – 0.088% ergot by weight.
Figure 2. 500 gram sample cleaned wheat – 0.04% ergot by weight.
Figure 3. Large foreign material removed in the cleaning process, containing a high percentage of ergot
Once a wheat crop is infected with ergot, there is not much a producer can do other than have it cleaned in hopes of being able to market the grain. There is expense involved, particularly if a second cleaning is needed, even more so if a gravity table needs to be part of the process, but that is better than having a crop you can’t sell. If the crop is yet to be harvested, one suggestion is to scout the field to see if certain areas have higher concentrations of ergot and harvest them separately. That may reduce the number of bushels that need to be cleaned to make them marketable. Also stated in an earlier column, “ergotty” wheat can also be improved by mixing it with grain which is free of ergot, but this approach should be taken with caution by individual producers in order to avoid contaminating clean grain. Wheat containing a high percentage of ergot may need to be cleaned before mixing with sound grain to ensure a marketable product, or if it is severely infested, may best be destroyed.
This article was written collaboratively by Bob Fanning, Emmanuel Byamukama, and Connie Strunk.
Source : SDSU