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Corn+Soybean Digest

Roundup Ready Corn: New Kid On The Block

Roundup Ready Corn, introduced exclusively last spring by Dekalb, is being watched more closely than the late-night visitors list at the White House.

Several other companies will offer Roundup Ready corn for 1999.

"Between 800,000 and 900,000 acres were planted this year," reports Dekalb's Vernon Benes.

Farmers and weed scientists alike are indicating favorable initial results.

"On a scale of 1 to 10, I'd give the Roundup Ready corn a 10 for both weed control and crop tolerance," says Jeff Ward, Mankato, MN. "It looked fabulous."

Ward planted 250 acres of it, primarily in fields with patches of tough-to-kill perennial weeds. He applied a half-rate of Harness pre-emergence, followed by 16 or 24 oz of Roundup Ultra when corn was 12" tall. Because growing conditions were favorable and he plants in 20" rows, he had a good early canopy.

"We got complete weed control at both rates of Roundup," Ward reports. "Results could be different another year, but this year looks great."

Dekalb's Benes claims research has shown that Roundup Ready corn is tolerant to Roundup even at twice the labeled rate. He also points out that, statistically, those hybrids and the same hybrids without the Roundup Ready gene have had the same yields in research trials.

Wayne Stevenson, professional farm manager with Farmcraft Service, Oxford, IN, planted Roundup Ready corn on a new farm with heavy weed pressure. Like Ward, he applied Harness pre-emergence to get early and residual activity.

"The Harness controlled grasses and most broadleaf weeds well enough that we were able to wait until the latest possible time for applying Roundup Ultra and therefore get more of the late-germinating weeds," Stevenson notes.

In the future, he hopes to combine another product with Roundup Ultra to pick up weeds on which it's not very strong, such as velvetleaf, morningglories and yellow nutsedge.

Southern Illinois University weed scientist George Kapusta has been evaluating Roundup Ready corn for three years.

"Although Monsanto's own application tips suggest that Roundup Ready corn doesn't have the tolerance of its soybean counterpart, we have not seen a tolerance problem," he says.

Grasses are more susceptible to Roundup than are broadleaf weeds, according to Kapusta.

"Until now, we have had only two good postemergence herbicides that control grass in corn and each costs $15 to $20 per acre," he points out. "Roundup costs $10 or less and also gets many broadleaf weeds the others don't."

There has been concern about volunteer Roundup Ready corn in the following year's soybean crop. But Monsanto's Norm Probst says that shouldn't be a problem.

"There are effective herbicides that can control volunteer corn in soybeans," he says.

Weed control options for Roundup Ready corn likely will be expanded for '99, says Probst.

"Hopefully, we will have approval for three choices."

The first option would be a pre-emergence herbicide followed by Roundup for weed escapes. The second would be Roundup plus a product with residual activity, applied when weeds are 4" tall. The third, pending EPA approval, would be a sequential program with Roundup only.

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