If you decide to plant insect-resistant corn hybrids in 2007, it is important that you also plant refuge acres, not only to meet EPA requirements, but for good stewardship of the technology.
Seed industry representatives say refuge compliance is now in the 92 to 95% range. But they are concerned that producers may not fully understand their refuge requirements, especially when planting the new stacked-trait Bt hybrids.
Bt corn hybrids all require a 20% corn refuge (50% in cotton areas) to prevent pest resistance. Depending on the Bt trait, the planting requirement for the refuge differs. Plant a corn rootworm trait, and the refuge must be planted in an adjacent field because the corn rootworm mating is localized. The refuge for the corn borer Bt trait can be planted one-quarter to one-half mile away. However, if you plant a stacked-trait Bt hybrid (one with corn rootworm and corn borer traits), you must adhere to the refuge requirement for the corn rootworm.
Entomologists stress that the refuge is necessary to ensure that at least some of the target pests survive and have the opportunity to breed with any pests that may have developed a resistance to either trait, especially the corn rootworm, which has a history of developing resistance.
Pest resistance pressure
The resistance issue becomes magnified this year as the corn industry anticipates a significant increase in Bt/corn rootworm acres as well as a shift to corn on corn. All the ingredients now exist for a significant increase in pest resistance pressure.
“University extension entomologists continually remind producers that it is indeed very important to utilize these refuges, especially as we look ahead and project more corn acres in 2007,” says Michael Gray, professor of entomology at the University of Illinois and co-director of the North Central Region Integrated Pest Management Center. “We have several rootworm and corn borer events in the market now and a tremendous adoption of the technology. The selection pressure will only increase as we increase the number of Bt acres and the number of acres being planted to stacked hybrids.”
Of major concern is proper adherence to the Bt refuge requirements. “There are some producers who are not in compliance, either unintentionally or intentionally,” says Marlin Rice, professor of entomology at Iowa State University. “If they are not following the refuge requirement, that's a big disappointment.”
Resistance, whether to insects or weeds, does occur over time. “Some people thought glyphosate would last forever,” Rice says. “But we're seeing more and more glyphosate-resistant weeds popping up across the Midwest. A good technology can be used and abused.”
That's why the companies that own the various Bt technologies are trying to educate producers on how and why to plant refuge acres. The Bt technology owners — Monsanto, DuPont/Pioneer, Dow AgroSciences and Syngenta — have teamed up in an Agriculture Biotechnology Stewardship Technical Committee to deliver a consistent message on the importance of refuge management.
“As we continue to introduce new traits and new technology, we are increasing our efforts to ‘respect the refuge,’ including launching a campaign with the same name to communicate refuge requirements and the benefits of stewarding our technologies,” says JoAnn Carden, Insect Resistance Management (IRM) coordinator for Monsanto. “Over the past three years, compliance has been on the increase.”
Dow AgroSciences has launched a number of educational activities to make sure that producers understand the IRM obligations. The company indicates that it will continue to provide rootworm control options to growers for refuge acres or to those growers who desire a traditional means of insect control in corn. “There remains a market for at-plant, soil-applied insecticides, and we want to provide quality alternatives to growers,” says Hank King, marketing specialist for U.S. insecticides.
Lance Bailey, product stewardship manager at Pioneer Hi-Bred International, says the company has focused its efforts on ensuring that the refuge requirements are being met. “The first area of confusion has been the distance requirement,” Bailey says. The second message is the use of stacked traits in the refuge. Most producers are familiar with the 20% refuge requirement. However, it is possible to plant 60% of a stacked trait, 20% corn borer and 20% corn rootworm and still meet the refuge requirements. “It's more complex, and that's why we're working to educate our sales reps and customers,” Bailey says.
The seed industry has attempted to simplify the refuge requirements for the Bt traits and to provide producers flexibility. “We didn't want to confuse growers with varying refuge management requirements,” says Paul Bertels, director of biotechnology for the National Corn Growers Association (NCGA). “Our message to the EPA was simple: Let's make the program consistent.”
Burrus Hybrids has addressed the refuge management issue aggressively. “As we have continued to sell more technologies, each spring we get more and more calls from customers asking about refuge management,” says Tom Burrus, president. “They're at the seed shed making their planting decisions and trying to determine what hybrids belong together. It can sometimes be a long time from when the seed is ordered to when it is poured in the planter.”
Burrus says, to assist producers, the company will make specific hybrid recommendations that start with the herbicide decision. “Most producers use only one system for corn, so to narrow the field of choices, we ask our customers what type of herbicides they use,” Burrus says. “Although that's not part of the refuge decision, it narrows the product choices.”
Although the EPA mandates record keeping and company audits, the ultimate responsibility for managing the technology falls on the shoulders of producers. “Many producers buy from more than one company,” says Tom Strachota, CEO of Dairyland Seed. “So it is ultimately up to the producers to ensure they are managing their refuge properly.” Nearly 300 corn companies are licensing the various insect protection technologies.
What happens to growers who decide to skip the refuge requirement and get caught by the EPA? Growers who are not in compliance will receive additional education from the license-holding companies to stress the refuge need and ensure that one is planted. If, in the second year, the grower again is found not in compliance, he or she will lose access to the technology.
“That has occurred this year,” Monsanto's Carden says. “We have a handful of growers who have lost access to our technology by not adhering to IRM and refuge recommendations.”
Producers can expect constant reminders on the importance of refuge management. “We are going out with a renewed effort this spring to remind producers to meet their refuge requirements,” NCGA's Bertels says. “If we don't, we're in jeopardy of losing this technology. A lot of growers don't realize that the Bt technology is no different than a chemical — it's a regulated product.” And as with other products, the EPA has rules for its use.
“A lot of the Bt technologies will come up for reregistration in 2008,” Bertels says. “And if we see our refuge compliance slip, we really don't know how the EPA will react, and I don't think we want to find out. There could be tighter restrictions on the technology, or even limited use. That's why we want to reinforce the IRM message so that compliance doesn't lapse.”
If resistance were to be discovered, it would be a black eye for the industry, says Christina DiFonzo, field crop entomologist at Michigan State University. And that could put additional pressures on any other new technologies in the pipeline.
Protect and preserve
THE BEST way to preserve the benefits of Bt technologies is to properly use and manage corn refuge acres. The first, and most important, step is to scout to determine if you have a rootworm or corn borer problem, and at what level. “A lot of producers may see lodged corn and think they have a rootworm problem, and that may not be the case,” says Christina DiFonzo, field crop entomologist at Michigan State University. “There are a lot of environmental factors that may hinder root development. The only way to know for sure is proper scouting.”
Michael Gray, professor of entomology at the University of Illinois, says 2006 fall surveys of European corn borer showed very low numbers in several areas of the state. He says, “That raises the question that producers should be asking: Do I need a Bt hybrid for corn borer control in 2007?”
Corn rootworm can be trickier. “I think that most producers don't scout for corn rootworms,” Gray says. “Lodging can occur for a variety of reasons, and the only way to assess damage or whether the infestation has reached an economic threshold is through scouting.”
Refuge acres can be managed with traditional insecticides, including seed-applied and soil-applied insecticides. “We encourage growers to manage their refuge acres for the best yield potential,” says Steve Knodle, Syngenta's Agrisure traits marketing manager. “That includes proper scouting to identify your pests, the economic thresholds, and which pests need to be controlled.”
It's also important that the hybrids planted on the refuge are of the same maturity as the insect technology hybrids and that they're planted at the same time.
It is possible to plant only Bt hybrids. For example, 60% of your corn can be planted to a stacked-trait hybrid, 20% to a corn borer hybrid, and 20% to a corn rootworm hybrid. That would meet the refuge requirements.
What you can't do is mix technologies and think you've planted a refuge. For instance, if you're planting 80% to a Herculex Xtra hybrid, you can't plant YieldGard on the refuge acres or vice versa.
For more information, visit www.ncga.com/biotechnology/IRMCenter/index.asp; www.herculex.net; www.ipm.uiuc.edu; www.monsanto.com/monsanto/us_ag/content/stewardship/ irm/2004/yieldgard.pdf; and www.monsanto.com/monsanto/us_ag/layout/stewardship/default.asp.