Published: October 27, 2005 10:31 am      

Aflatoxin attacks corn

CLINTON — First it was a near-record lack of rainfall. Then it was record-breaking summer heat. Then insects came and ate the corn silks in some fields, thus preventing the corn tassels from pollinating the ears.

Now that the corn is being harvested, some of it is being rejected at the elevator because it tests positive for aflatoxin.

According to an Iowa State University Extension Service Web site, aflatoxins are a group of chemicals produced by certain molds on corn kernels. Aflatoxins are carcinogenic and can cause cancer in both animals and humans.

They also can be fatal to livestock if eaten as part of a feed ration.

As a result of the seriousness of the problem, a lot of testing is being done in Clinton County, according to Virgil Schmitt, extension service crop specialist for Eastern Iowa — but test results are not always reliable.

The first indication of possible aflatoxin contamination is a yellow-green or gray-green mold that is visible on the corn, he said. But the aflatoxin itself is inside the kernels.

“If we see the mold, it may or may not have produced aflatoxin. On the other hand, it’s possible for the mold to be growing inside the kernel and you don’t see the evidence on the outside,” Schmitt said. “It’s really kind of a messed-up deal.”

The first test is done with a black light. If that indicates possible aflatoxin, a sample of the corn is sent to a laboratory for more sophisticated testing.

“In theory, crop damage from aflatoxin is covered by insurance, as long as the contamination is found before the corn goes into storage or is offered for sale,” Schmitt explained. “But there is, with some frequency, a scenario where an insurance adjuster takes a sample of corn and it comes back negative for aflatoxin, but still the farmer can’t get it sold because it tests positive at the elevator.

“And Federal Risk Agency rules say an adjuster can’t go back into the field a second time (to test again), which means the farmer is out of luck. We’re trying to get that position reversed, but that’s where it is at this time.”

Some farmers have fared far worse than others when it came time to sell their crop.

“I haven’t gotten much of a feel for the big picture on aflatoxin in Clinton County yet,” Schmitt said, “but I’ve heard instances where 80 percent of the loads were rejected on some days. Then, again, I’ve heard of 20 to 25 percent being rejected.”

There are places a farmer can sell corn contaminated by aflatoxin, Schmitt said, although he said he did not know what the price spread would be. Those businesses sometimes blend diseased corn with other corn to reduce the level of aflatoxin and make it safe to feed. The rejected corn also can be used as an energy source for furnaces.

“I wouldn’t want to get it into my house,” Schmitt said, “but if you have a unit that sits outside, it’s an excellent energy source. The aflatoxin is totally destroyed by the fire, so there is no pollution.”

Turning to the subject of the yields sitting in fields waiting for harvest, Schmitt said it’s still too early to tell.

“But what I’m hearing is that yields are better than most people thought they would be, with a lot of variability depending on whether a field got a little pop up shower and what the soil type was.”

The 2005 growing season delivered “almost a quadruple whammy” to farmers, he concluded.

“Normally, if you have a low yield the price goes up. But this year there is so much corn elsewhere that supply and demand didn’t work. So Clinton County farmers have a combination of low yields and low prices.

“Then, with Hurricane Katrina messing up the barge traffic up and down the Mississippi River, the difference between our low price and the price at Chicago is at a near-record spread.

“And on top of that, you throw in the aflatoxin and fuel prices going through the roof — it’s going to be a real challenge for people.”

Some help, in the form of low interest (3.75 percent) loans, is available from the Farm Service Agency for farm operators who suffered major production losses due to the drought.

A brighter picture in Clinton County is the yield of soybeans that survived the early summer drought and responded to August rains. Beans on sandy soil were already brown before the rains came, but those on better soil are yielding close to the five-year average, according to Schmitt.

And aflatoxin does not invade soybean fields.