Producers harvesting grain with significant levels of fusarium head blight (scab) may need to take extra steps to improve the quality of their harvested grain, according to a North Dakota State University agricultural engineer.

"Some areas in the state have shown a significant incidence of scab in small grains. The disease can cause a major reduction in test weight and grain quality," says Vern Hofman of the NDSU Extension Service. Scab can be identified by a pink discoloration on the kernels and shriveled kernels.

"Running the combine-cleaning fan at the high end of the speed range may help blow some of the lighter kernels out, but past experience has shown that a more intense cleaning than what the combine can do will be needed," Hofman says. Other combine adjustments should be made as recommended in the operators manual and final adjustments made based on field conditions.

The best cleaning may require a fanning mill (for air cleaning) and a gravity table, Hofman says. A gravity table will separate grain by test weight. However, in heavy scab infestations, a gravity table may not provide significant improvement in grain quality if many moderately infected kernels are present. Infected kernels are approximately the same size and density as uninfected kernels.

Cleaning infected grain with a fanning mill will reduce scab and vomitoxin levels, but air cleaning will result in a significant loss of nonscabby grain as well because of the air levels needed to get rid of the scabby grain, he says. To determine if cleaning is going to be profitable, producers should compare the price for scabby grain to the cleaned-grain price, minus the cleaning cost. Cleaning may pay for some producers and not for others, Hofman notes. The scabby portion may be sold for ruminant livestock feed so long as it does not contain prohibitive levels of vomitoxin. It also may be a good idea for growers to harvest portions of fields with high levels of the disease separately from those that have low infection rates. That strategy is more easily accomplished while straight combining than when swathing. This strategy requires producers to keep heavily infected grain in separate bins.