Weird weather, from too dry to too wet to downright deadly from a series of tornadoes that left debris spread across thousands of acres of North Carolina farmland, has delayed corn planting statewide.

Planting a couple weeks later than ideal likely won’t have much impact on the final state yield of corn, says North Carolina State Corn Specialist Ron Heiniger. However, it will put corn at much higher risk of aflatoxin in the crop and can significantly impact quality and price of the 2011 crop.

The veteran North Carolina State University researcher says work he’s conducted recently with a new product, Aflaguard, offers great hope for farmers who were forced to plant corn late this year.

Avoiding economic shortfall associated with aflatoxin-infested corn, he says, is important to take advantage of today’s high grain prices to growers.

Aflatoxin is a toxic metabolite produced by the fungi, Aspergillus flavus and A. parasiticus. Aspergillus spores can infect corn ears and kernels through silk channels, wounds caused by birds, hail and a variety of ear-feeding insects or through other openings in the seedcoat such as silk cuts and stress cracks.

Hot, dry weather is a well known trigger for Aflatoxin development. Late planting exposes corn plants to more prolonged periods of heat and dry weather in the upper Southeast.

Aflatoxin is more likely to occur in the field in years characterized by high temperatures and drought, and may also occur in grain not properly dried or stored.

Hail damage is another source of stress more typically associated with corn that is exposed longer to mid-to-late summer heat. Corn ears damaged by hail are prone to develop fusarium ear rot and aspergillus ear rot.

Some things help

There are a few things farmers can do to help overcome the risk of aflatoxin in late-planted corn.

Selection of regionally adapted hybrids with drought tolerance, combined with high grain quality is a good first step. Though relatively few corn acres in the upper Southeast are irrigated, timely application of water is another way to reduce risk.

At harvest time growers can minimize aflatoxin risk by combining corn when it is first ready. Setting combines to minimize broken and lightweight kernels will help, as will rapid drying and separate storage of grain from irrigated fields versus dryland fields.

In corn, aflatoxins are measured and regulated in parts per billion. One part per billion is equivalent to one second in 32 years or one kernel of corn in a 10,000 bushel bin.

A good target for farmers to shoot for is 20 parts per billion of aflatoxin. Though some uses, such as feed for mature cattle, can be 200-300 parts per billion, sticking to the 20 part per billion limit will pay off for farmers.

In most states, corn with aflatoxin levels of 20 parts per billion or higher cannot be sold for transport across state lines. Limitations for use of aflatoxin infested corn extends even to ethanol production, because of the risk of contaminating distillers grain, a by-product of the ethanol production process.

A five-year comprehensive study on the cost of aflatoxins to the U.S. food industry is in its final stages and scheduled for release in September.

A separate USDA case study in corn estimates that the total measurable annual loss to the U.S. corn industry is $192 million. Of this amount, market losses make up $163 million, livestock health losses $4 million, and sampling and testing costs $25 million.

In addition, “intangible” economic losses, including the costs of grower disposal of contaminated corn, sampling errors, losses on a geographical basis, and losses associated with aflatoxin concentration in the production of ethanol, increase the average annual loss due to aflatoxin in corn to over $200 million.

Best option

Clearly, the best option for farmers is to not get aflatoxins in their corn. In the past, other than praying for rain, there wasn’t much a farmer in the Southeast could do to prevent aflatoxin problems.

“Whenever we plant later and get into more heat and drought stress during silking and pollination, that’s where we set the stage for aflatoxin. Planting later is typically the ticket for getting aflatoxin in corn,” says Heiniger.

The North Carolina State corn specialist says he began working with Aflaguard three years ago. It’s basically a naturally occurring strain of aspergillus flavus that doesn’t produce a toxin. It contains the same fungus, but it doesn’t produce the damaging toxins that cause problems in corn, peanuts and a number of other crops.

“Basically what happens with Aflaguard is that you apply it to a field and it takes over the field — it doesn’t kill harmful aspergillus flavus fungi, it just dominates the field and essentially crowds out these damaging strains of fungi,” Heiniger says.

“In our tests, we put down contaminated corn we know has aspergillus in it, so we’re sure we have plenty of fungal spores in the air. We treat these fields with Aflaguard and compare them with check plots to see how much of the harmful fungi are crowded out.

“Across the state, the results have been startling. We had six replicated tests and three more with side-by-side tests in farmer’s fields. In fields treated with 5-10 pounds per acre of Aflaguard, we find virtually no aflatoxin. The company that sells it  (Syngenta) advertises 87 percent control, but we are seeing 98-100 percent control in our tests,” Heiniger says.

For growers who raise swine or poultry or farm organically, this is a premium product. Livestock growers are going to remove virtually all the aflatoxin and will help a producer grow a healthier, better producing animal, Heiniger says. For farmer-feeders this product is just about a no-brainer, he adds.

In the past, mills have historically used a binding agent because they knew they would likely get a little aflatoxin in corn they buy from North Carolina. Heiniger says he and his Extension colleagues are trying to convince mills they don’t need these binding agents, at least not on corn treated with Aflaguard.

The North Carolina State corn specialist says he would ideally like to work with Syngenta, the company that markets Aflaguard, to set up a monitoring site, most likely a website that gives growers a rating on how likely contamination is to occur.

An ideal situation

“Last year, for example, we had high temperatures and dry weather coming into silking season. In a year like that every grower should consider using it, because the chance of aflatoxin occurring is very high under those conditions.

“On the other hand, a year like 2003 when we had cool, damp weather the first few weeks of June, during the prime silking and pollination period for our corn crop, the chances of aflatoxin developing were very low,” he says

One drawback of using Aflaguard is application method. Because corn is so high at the time the product is applied, it must be applied by air, or by a specially built high clearance ground sprayer.

Heiniger says they are looking at different application rates and liquid formulations of the product this year.

With corn roughly head high, it’s going to be difficult to do anything other than fly it on, but if we back the application date up a little before corn gets so tall without losing efficacy of the product, that would help growers.

“We worked with Syngenta last year to look at different liquid formulations of the product. We didn’t get quite as good results as with the dry formulation, but there’s nothing magical about dry versus liquid, it’s just a matter of getting the formulation to maximize product efficacy,” he adds.

“With the cost of the product ranging in the $20 per acre range, when you factor in the higher cost of aerial application, farmers would be more likely to use it, if they had some way of knowing when their crop is at higher risk,” Heiniger says.

“The active ingredient in the product is naturally occurring and causes only good things to happen, so from an environmental standpoint it is ideal. There is nothing fancy or transgenic about this product.

“For sure aspergillus fungal spores still get in the corn, but these are good spores that don’t cause any problems,” Heiniger says

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