Corn producers are beginning to harvest their crop in Colquitt County, and so far I have been hearing some good yields (220 bu +). This corn crop has seen its fair share of difficulties due to a period of hot, dry weather followed by a very rainy weather pattern. We’re hoping for a safe and successful harvest season.
Below is information from the UGA publication Reducing Aflatoxin in Corn during Harvest and Storage. Here’s an excerpt:
Research shows most Aspergillus infection occurs on corn in broken and damaged kernels and in foreign material. Damage to the grain seed coat permits easy entrance of molds and fungi, and promotes rapid development of storage rots at high moisture and temperature levels. Heat and drought stress can cause seed coat fractures and increase the opportunity for infection to occur. Aflatoxin can develop within 24 hours in mold- and fungi-infected corn stored under these conditions, even though corn was previously free of aflatoxin.
Harvesting must be done in such a way to prevent damage to the seed coat and to assure maximum cleaning of grain, since damaged seed and foreign material contribute to the development of aflatoxin. The following practices will reduce the likelihood of this problem.
When corn reaches maturity, harvest immediately and dry mechanically. Harvest should begin when the moisture level reaches 28 to 30 percent. Studies have shown that most corn hybrids will normally lose about 0.5 to 0.6 percent moisture per day during the dry-down period. You can reduce field exposure by at least 1 to 2½ weeks by harvesting above 22 percent moisture compared to letting corn dry in the field to 15 percent or less. This will require immediate drying, however.
Irrigated corn generally has fewer problems with Aspergillus infection due to better growing conditions (less drought and heat stress, etc.). If corn is irrigated, harvest the crop outside the pivot separately and store it separately to reduce chances of contaminating good corn. Be sure the clean the combine before harvesting the irrigated corn.
Set combines to minimize grain damage. Set fans higher to clean out light-weight cracked grain and undeveloped kernels. Slowing header seed reduces kernel damage. Ears in contact with the ground for some time usually exhibit higher than normal aflatoxin levels and should not be picked up, if possible.
Combine cylinder/rotor speed should be slow enough and concave clearance as great as possible to provide adequate threshing. Less damage to seed coat occurs with these settings. Install filler plates between cylinder bars to reduce physical damage.
Do not hold high moisture grain in wagons or trucks longer than 6 hours. Place high moisture corn being held for drying in a holding bin using forced air to keep it as cool as possible.
Use sound sanitation practices in handling grain. Clean augur wells and pits, and clean around dump stations before and after each use. Minimize physical damage by conveyors or from dropping the grain into tall bins.
Drying temperature and drying time may have an effect on the development of aflatoxin in stored grain. Slow drying with low heat over long periods could promote aflatoxin development.