August 31, 2012

As most rain-fed corn producers are well aware, this year’s hot dry conditions have resulted in lower yields with moderately lower test weights. They have also brought concerns about potential mycotoxin contamination in the grain.

Bin Tips

Given the potential for molds and mycotoxins from this year's crop, be sure to extend some extra care to cleaning up harvest equipment now and grain bins later.

• Next summer, clean out grain and grain dust from bins after they're emptied.
  
  
• If the bin contained moldy grain, spray disinfectant on all inside surfaces. Use a solution of 3/4 cup of household bleach per each gallon of water.  (That's equivalent to 1 gallon of bleach to 20 gallons of water.) Remember that chlorine fumes are dangerous and this clean-up job requires good ventilation.  Also, never mix bleach with ammonia or vinegar.

The only way to know if there are mycotoxins in your grain and which specific mycotoxins are present is to have representative samples tested by a certified lab. If the initial screening indicates the presence of mycotoxins, quantitative tests should be run to determine the level of contamination.

Grain Storage Management

Many species of fungi cause mold in grain. Most become associated with the grain in the field, but may continue to grow and reproduce if grain is stored under the wrong moisture and temperature conditions in the bin. If there is a chance molds that produce mycotoxins may have contaminated the bin, dry the grain to 14% moisture. If it will be stored for over a month, dry it down to 13%.

If the corn is found to have any level of mycotoxin contamination, partially fill the bin — one-fourth full is a good place to start — so the fan will produce higher airflow rates (cfm/bu) and dry the grain quicker. If equipped, run a couple rounds with the stirring system, then run a few rounds each time you add 4 or more feet of corn into the bin to equalize the moisture content and prevent over-drying the bottom of the bin. However, don’t overstir as it can cause cracks in the seed coat that can allow fungal organisms to enter the kernels

In addition to getting the corn dry, you need to cool the grain whenever air temperature allows. This will slow the growth rate of the fungal organisms. Run the fans at every opportunity when the air temperature is 10 degrees below the grain temperature in the bin. Continue running fans until the grain is 30° F but there is no need to get it colder than 30°F.

Resources

For more information on grain storage, see the Grain Storage Management section of the Lancaster County website.

Tom Dorn
UNL Extension Educator