Fargo, North Dakota
August 4, 2005
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. |