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Refuge reduced

THE NUMBER of refuge acres required for crops from multi-stacked seeds is decreasing thanks to new technology from seed companies. The first big drop in refuge acres comes with the new SmartStax seed that needs only a 5% refuge compared to 20% for other traited seed. Codeveloped by Monsanto and Dow AgroSciences, SmartStax will be widely available for planting next year.

Other companies are considering reduced refuges as well. Pioneer Hi-Bred and Syngenta are each working on their own “refuge-in-a-bag” product that allows the grower to plant an entire field to the bag product. These technologies will simplify refuge planting for the grower.

In addition, Syngenta plans to petition the EPA for reduced refuges for both corn borer and lepidopteran on a new stack of the Agrisure Viptera trait, the Agrisure CB/LL trait, and Herculex I trait.

Lower refuge requirements will lessen growers' concerns about potential yield loss in refuge acres that are not protected by Bt toxins in the plant, says Robert Wright, University of Nebraska Extension entomologist. “This is particularly important in cotton-growing areas where a 50% non-Bt refuge is required for Bt corn,” he says.

Plus, the new refuge-in-a-bag technologies should help bring compliance up to or close to 100%. There are some industry concerns that compliance has not been as good as it should be. Keeping a reservoir of susceptible genes in the corn rootworm population is key to preserving the longevity of these products, reports Christian Krupke, Purdue University Extension entomologist.

Refuge acres crucial

The SmartStax multi-event technology will be available from more than 150 licensees and may be planted on three to four million acres. With the percentage of required refuge acres reduced to 5% in the U.S. Corn Belt and Canada, the amount of soil insecticides used in North America will be significantly reduced. Therefore it is even more important for growers to correctly maintain the refuge acres to protect against potential insect resistance, Krupke says.

A big question is how growers will design their refuges. For the 5% requirement, most growers will probably place a block aside, planting it either before or after the acres devoted to the multi-event technology, Krupke says.

However, different refuge sizes may be required for Bt corn hybrids from different companies. “Bt corn is used on a high percentage of acres in many parts of the U. S.,” Wright says. “Because of this, there are concerns about the potential for resistance development. Since Bt proteins have many advantages over conventional insecticides, in terms of safety to the applicator and to the environment, it is important that we maintain the effective life of this technology by following approved resistance management plans.”

In the end, growers should still give priority to hybrid selection. “There are a lot of options, and granular insecticides still work fine,” Krupke adds. “Consider everything. If something's working, keep on using it. Don't get caught up in hype.”

Calculate cost-benefit

Given the good levels of in-plant trait protection against the European corn borer and corn rootworm, growers should consider both the benefits of this protection and the prices charged for the seed. To help growers calculate their per-acre costs, Mycogen Seeds has developed an online calculator (

Feedback indicates that growers lose 10 to 20 bu./acre in corn refuges compared to acres with in-plant protection in the rest of the field, says Brent Stauffacher, SmartStax product manager, Mycogen Seeds. Making up the difference in 15% (or 30% in the Cotton Belt) of producers' acreage can be attractive.

SmartStax technology combines Dow AgroSciences' Herculex Insect Protection with Monsanto's Genuity VT Triple Pro. SmartStax also offers belowground insect control by combining Monsanto's YieldGard VT Rootworm/RR2 with Dow's Herculex RW Insect Protection. Finally, SmartStax combines Monsanto's RR2 with Bayer CropSciences' Liberty-Link herbicide tolerance.

Matt Kirkpatrick, Monsanto corn traits marketing manager, observes that these multiple modes of action reduce the risk of the occurrence of insect resistance.

Monsanto is not the only company pursuing smaller refuges. Syngenta recently announced that it is compiling data to make a submission to the EPA for a reduced block refuge on a future stack of the Agrisure Viptera trait with the Agrisure CB/LL trait and the Herculex I trait.

Pioneer's refuge in a bag

The EPA is currently evaluating Pioneer Hi-Bred's corn rootworm refuge integrated in the bag. The technology is called Optimum AcreMax 1 (OAM1)insect protection system. Pioneer says that this system will have the ability to deliver higher overall farm yields because a grower won't have to plant a separate non-traited refuge hybrid.

The integrated approach will put the refuge throughout the field where it needs to be to deliver crop protection and simplicity, says Bill Belzer, Pioneer corn marketing manager. When a grower uses a refuge hybrid in a block or strip design, the refuge hybrid has to match the in-plant-protection product's maturities, herbicide tolerances and so on. The producer also needs to start and stop the planter and clean out the hoppers when planting both traited and non-traited hybrids.

An integrated approach could help eliminate these hassle factors for growers, Belzer says. Upon approval, the OAM1 system would allow a grower to plant an entire field to an OAM1 product and then plant the needed European corn borer refuge in a different field up to one-half mile away.

In testing, OAM1 products have shown performance equivalent with their Herculex Xtra counterparts. Belzer notes that the new technology would enable growers to switch over at-risk refuge acres to performance acres. “The grower would benefit from in-plant protection on formerly untraited acres,” he says.

“We're interested in reducing refuge requirements and ensuring the durability of these proven traits,” Belzer says. “Our next step is to add an additional mode of action for aboveground insects to deliver a single-bag option for refuge. Farmers are some of the best technology stewards and understand the importance of these traits. We're helping them with new options to manage this technology.”

Future refuge options

In addition, Syngenta hopes to petition the EPA and receive approval for a refuge-in-a-bag product that it calls Agrisure EZ Refuge. This product will include a stack of the Agrisure 3000GT, Viptera and Herculex Xtra traits. The petition for this product also will ask for a reduced refuge nationwide on corn borer and corn rootworm acres.

Monsanto also has been evaluating the refuge-in-a-bag concept for more than a dozen years. It reports that it had a large number of trials in fields this past summer.

“Growers tell us they want the convenience of refuge in a bag, but our first priority was to get EPA approval for the reduced refuge to 5%,” Kirkpatrick says. “We will make a final commercial decision on Genuity SmartStax RIB after all yield trials are analyzed this year.”

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