As their combines slice through corn fields, they are discovering high yields, despite a spell of dry weather last July.
The market is also strong this year. Corn prices are up, adding a positive profit margin to this year's crop.
Not all is perfect, however. A unique problem is plaguing some area corn fields. In acreages that are severely affected, portions of harvested corn may need to be destroyed.
The problem is aflatoxin.
"I don't know if disease is the right word to describe it," said Kevin Myron of Ag Opportunities in Vermillion. "It's a toxin that develops on severely stressed corn. It typically comes along in drought years, or in severely stressed corn – perhaps in corn that has been hailed on – but we're seeing an incredible amount of aflatoxin corn showing up this fall."
The South Dakota Corn Growers Association (SDCGA) sent an alert to local farmers through the media in late October, urging them to check their fields.
It also has launched a widespread educational effort to alert corn producers to check for aflatoxin before clearing fields.
Farmers should take the time to test for aflatoxin, according to the SDCGA, particularly before storing corn as crop insurance will not cover losses in the bin. Insurance ends at harvest.
Counties in South Dakota where aflatoxin has been found include Clay, Lincoln, Turner, Union and Yankton.
Growing conditions were ideal for aflatoxin to develop during dry and hot conditions in July followed by recent multi-day rainfall received throughout the state.
Myron has had several conversations with SDCGA staff members.
"Unfortunately, I've had to learn quite a bit about this," he said. "I've been in this business 15 years and never had to deal with this. This is one of the first widespread cases of this I've had to deal with."
Myron noted that the Food and Drug Administration has established accepted uses for corn affected with aflatoxin.
The tests that detect it in corn measure the levels of the toxin in parts per billion (ppb).
Corn that tests in a range between zero to 20 ppb is generally accepted.
Corn containing aflatoxin at a range of 21-300 ppb may be fed to finishing feeder pigs at 200 ppb or less, and beef in feedlots can tolerate up to 300 ppb. There is zero tolerance for aflatoxin in dairy products.
There is no permitted use, however, for corn that tests over 300 ppb. It is recommended that corn that contains that much aflatoxin be destroyed.
Reid Jensen, president of the SDCGA, said its crucial that farmers contact their insurance agents before beginning harvest.
"Testing for aflatoxin before combining may slow producers down a bit but would save them thousands of dollars in losses due to discounted or rejected grain because of aflatoxin contamination," he said. "Producers must act now to prevent grain losses."
Myron noted that the fungus can't be detected simply by looking at the corn.
"That's where this is a real challenge," he said. "There's no magical machine that can test for this. You basically have to use a lab-type test to detect it."
There are three processes used to test for aflatoxin.
"This may sound funny, but one of the ways you can test aflatoxin is using a black light," Myron said. "You scan that over the corn, and one of the components of the aflatoxin will light up as a bright fluorescent yellow."
A black light, however, isn't foolproof, he said. There's a chance that, in some samples, the fungus won't be detected using this method.
"We scan every load with a black light, and then we do strip tests," Myron said. "They take about 15 minutes to do. You grind up the corn, mix it with a chemical, and then put these strips in the sample. It will give us a pass or fail for being over or under 20 parts per billion."
Corn samples that test over 20 ppb are sent to a licensed federal grader for a more accurate reading.
Fortunately, aflatoxin is covered under federal crop insurance. "But to be covered under the insurance, if farmers intend to store the corn in a bin, they have to determine if it has aflatoxin prior to putting in the bin," Myron said. "Aflatoxin will intensify in storage, particularly if it is wet, so it is recommended to farmers who are combining that the corn be dried within 24 hours."
The harvested kernels should be dried down to 13 percent. The accepted level for safe storage of unaffected corn is 15 percent.
According to Robert Berg with the SDSU Southeast Experiment Station in Beresford, crop insurance groups claim that farmers will automatically lose their crop revenue protection coverage entirely if infected corn is stored in a bin.
Adjusters can still work with farmers, but only if the grain is still in the field or on the truck.
The presence of aflatoxin has made this a busier than usual time for farmers, insurance adjusters and farm marketplaces like Ag Opportunities.
Myron's tasks this fall include not only testing for the fungus, but also trying to find places that may utilize affected corn.
"We are accepting it (corn with aflatoxin)," he said. "We have three feedlots we are working with that will take it. That's after calling 55-plus feedlots."