Aflatoxin worries piling up

Aflatoxin worries piling up

By: Jeff Caldwell 08/27/2012 @ 9:59am

There are a lot of expectations for a quick corn harvest this fall. That's reasonable, some farmers say, given the crop's going to be short and dry. But, on the contrary so far, some early loads to the elevator show it may not be as quick and relatively painless as many had hoped.

Blame aflatoxin. The fungal disease loves hot, dry years like this one, and now that more combines are starting to roll, there are signs that harvest won't be as brief as once thought. Farmers say they're already seeing more testing for the disease -- which can be potentially fatal for livestock when consuming infected corn -- and in addition to making it possible for some loads to be turned away by the elevator, it's adding time to the process of taking grain to town.

"Every single load is getting a DNA test to check for aflatoxin. Takes about 10 minutes," says Agriculture.com Marketing Talk senior contributor Hobbyfarmer. "They are practicing on the old corn to get a hang of the procedure. Good thing there is a very short crop here. Ten-plus-minute wait after leaving the scale. Twenty parts per billion is the threshold for rejection."

That 20-ppb threshold has always been a bone of contention; that can amount to a mere handful of kernels in some truckloads, making testing a hit-or-miss affair, some farmers say. But, that's the rule, and it makes it important, if you think you have a field that's got mycotoxins present, to take the right steps, says Marketing Talk veteran contributor WCMO.

"If you think you have aflatoxin, have been told you have aflatoxin or just want your corn 'officially' checked, then stop what you are doing and call your insurance agent pronto," he says. "An insurance adjuster can sample your unharvested field, or obtain samples while you are harvesting, or give you additional instructions. You are not allowed to pull your own samples, and insurance probably cannot accept aflatoxin determinations from your local elevator. If you harvest the field and put it in the bin, the adjuster cannot pull samples for aflatoxin from the bin."

There are ways to make an educated determination whether your fields need to be tested before you run the combine, though. For one, scout for Aspergillus ear rot first, as that disease is a common precursor to aflatoxin. Start with your fields that have historically been susceptible to ear-feeding bugs like the corn earworm, says University of Nebraska Extension plant pathologist Tamra Jackson-Ziems. Open husks to "view a large number of ears," then look for "the presence of dusty yellow-green to olive-green spores along the edges of kernels when scouting, she says. And, start with fields where you suspect your crop's incurred the most drought damage.

"Ear rot diseases and aflatoxin are not evenly distributed across fields or in the grain, so scouting and/or sampling should include a substantial portion, at least several acres," she says. "The presence of the fungus in kernels does not always correlate well with the presence of aflatoxin, nor does the absence of visible fungal growth necessarily indicate the absence of aflatoxin."

If you do need to harvest a field where you've confirmed Aspergillus ear rot and you suspect that's caused aflatoxin to thrive, make sure you keep it segregated from the rest of your grain; keep it aerated and cooled to prevent further fungal growth, Jackson-Ziems says. If you have the storage capacity, grain can be commingled later on to thin out the concentration of aflatoxin.

But, don't wait until you've got the grain in the combine before you take action, adds Hobbyfarmer. Though you do have a few options after harvest, it's best to be proactive and get a full picture of your aflatoxin risks before you turn a wheel.

"If you have an aflatoxin issue, don't wait until harvest before you know the severity of the issue. There are levels that will cost you if you harvest before knowing what you are dealing with. My guess is it is not going to be the issue it is hyped to be, but there are always exceptions," he says. "You can take your own for testing to see where you are at before you make that million-dollar mistake and wind up with a completed harvest and unsellable crop in the bin and no insurance because of it."