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ExpressSun Option Pays for N.D. Growers in 2007

Friday, February 1, 2008
filed under: Weeds

There’s a dirty 10-letter word in Paul Ivesdal’s vocabulary: marshelder. For years, the northeastern North Dakota producer has struggled to control heavy infestations of this broadleaf in sunflower fields.

That changed dramatically in 2007, however, when Ivesdal seeded about 550 acres — a third of his total sunflower acreage — with an ExpressSun™ variety. The difference was, in his term, “unbelievable” in one field with a very high marsh-elder population. “I would not have had any yield in that field if I hadn’t sprayed Express®,” Ivesdal states. He adds that on one field edge where he was a little late in turning on his spray boom, the ground was overcome by marshelder to the point where the sunflower rows were not even visible.

Ivesdal, who also counts on Express to control wild chamomile and other broad-leaves in his sunflower fields, plans to increase his ExpressSun usage to about half his sunflower acreage in 2008. While it did add to his seed cost, using the ExpressSun variety easily paid for itself in final yield, he emphasizes.

Clients of Mike Hutter, a veteran crop consultant and owner of Northern Ag Management at Westhope, N.D., planted about 700 acres in the ExpressSun variety last year. He expects that figure to jump substantially in 2008. “I have one client who has already secured 1,800 acres” of ExpressSun seed, Hutter relates.

Weed control is the driving motivation behind his Bottineau County growers’ planting of ExpressSun, Hutter affirms. Canada thistle is one of the main targets — one for which the Express option provides a nice insurance policy. “If you were unable to apply a preharvest or postharvest glypho-sate treatment [to wheat or barley ground] the fall previous to sunflower — and we were extremely dry in Bottineau County in the fall of ’07 — you may not know what to expect from Canada thistle” in the sunflower year, Hutter points out. “By planting an ExpressSun variety and spraying with Express, you have an ‘ace in the hole’ to pull out of the toolbox if you need it.”

The other feature Hutter likes about being able to spray Express on sunflower is it “separates the grass control from the broadleaf weed control, postemergence.”

That’s different from a Clearfield® program, he notes. “When you grow Clearfield, you have a product — Beyond® — that is for both grass and broadleaf control. But it doesn’t give you a chance to tailor the rates of the grass herbicide differently than the broadleaf.

“Whereas with Express, you would add your own Assure II or other grass herbicide along with whatever rate of Express you need,” depending upon the weed species targeted and their levels of infestation.

One caution: “Express will not control kochia,” Hutter adds. Given how much resistant kochia presently exists across the sunflower production region, “I feel we still have to start with a Spartan treatment — as we would if we were growing Clearfield sunflower.” As an ALS-inhibitor, Express will not control ALS-resistant weeds.

Last year was the first for which the ExpressSun option was available to growers. Pioneer Hi-Bred offered one ExpressSun variety — 63N81 — on a limited basis to Upper Midwest growers in 2007. For 2008, Pioneer is introducing two more hybrids with the herbicide-tolerant trait. One is a mid-oleic NuSun variety; the other a high-oleic hybrid. Seeds 2000 is the only other company offering an ExpressSun variety this year. Its Firebird is a medium- to late-maturing NuSun hybrid.

The Express-tolerant trait is incorporated through traditional plant breeding methods, so ExpressSun hybrids are considered to be “non-GMO” products. Express herbicide (with TotalSol™ soluble granules) is a member of the sulfonylurea family of herbicides. It has been widely used in wheat and barley for about 15 years for postemergent control of broadleaf weeds.

EPA’s 2007 labeling of Express for use on sunflower was the culmination of a cooperative effort by DuPont, the National Sunflower Association, universities in major sunflower-producing states, USDA’s IR-4 project (which helps conduct research on pesticides for “minor” crops), and the North Dakota Minor Use Fund (which financed the required residue trials). The ExpressSun trait has also been approved by Canadian regulatory agencies for use on sunflower in that country.

Express is applied postemergence at rates of between 0.25 to 0.5 oz/ac, with a maximum of 1.0 oz/acre per use season. A methylated seed oil adjuvant is used at a rate of one gallon per 100 gallons of spray solution. Recommended minimum spray volume is five gallons by ground or two gallons by air. Express can be applied anytime between sunflower’s one-leaf stage up to (but not including) bud formation. There should be at least a two-week interval between applications. — Don Lilleboe
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