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Producers advised to protect yields using pre-emerge herbicides

By Staff | Mar 27, 2009

CARROLL – With the increased price of inputs for the 2009 growing season, it’s more important than ever to squeeze every bushel of yield possible from a crop, said Mark Licht, an Iowa State University Extension agronomy field specialist based in Carroll County.

Using pre-emerge herbicides in a weed control program can provide a maximum return on investment, in addition to resistance management and increased flexibility in application timing.

“Farmers want to make sure they have effective weed control to protect yields, so pre-emerge herbicides will be utilized more this year,” said Mark Licht, an Iowa State University Extension field agronomist based in Carroll County.

The more researchers learn about weed control, it becomes clear that weeds must be controlled earlier rather than later, Licht said. When weeds are permitted to thrive early in the season, they steal vital moisture and nutrition from the growing crop.

According to Syngenta, weeds that are allowed to compete with a soybean crop to only the 2-inch stage have already stolen more than 16 bushels per acre.

A residual pre-emergence herbicide for early-season weed control also broadens the application window and holds weed pressure back, allowing more flexibility for post applications, Licht said.

Managing resistance

The wide adaptation of Roundup Ready technology also raises the importance of addressing herbicide resistance in weeds, said a recent survey conducted by ISU. In it, Iowa farmers agreed that glyphosate is effective and provides adequate weed control, although many producers admitted they are using increasing rates to get this control, Licht said.

Most pre-emerge applications will add an additional mode of action to a weed control program, which can help manage resistance issues.

“The message is simple,” said Mike Roegge, a University of Illinois Extension educator. “For the most efficient use of Roundup Ready crops, use a pre-emerge herbicide to reduce the opportunities for weed resistance, as well as give you more time to apply the post emerge glyphosate.”

Roegge also recommends applying the post-emerge application of glyphosate based upon weed size to achieve the highest economic return.

Numerous research projects have been conducted to determine the optimal time to apply post-emerge glyphosate.

“They’ve all shown pretty much the same results,” Roegge said. “Control weeds in corn when they’ve reached the 4-inch stage, and in soybeans when they’ve reached the 6-inch stage. Delaying from these intervals guarantees a yield decrease, because the weeds are much more competitive than the crop is.”

You can contact Darcy Dougherty Maulsby at yettergirl@yahoo.com.

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Producers advised to protect yields using pre-emerge herbicides

By Staff | Mar 27, 2009

CARROLL – With the increased price of inputs for the 2009 growing season, it’s more important than ever to squeeze every bushel of yield possible from a crop, said Mark Licht, an Iowa State University Extension agronomy field specialist based in Carroll County.

Using pre-emerge herbicides in a weed control program can provide a maximum return on investment, in addition to resistance management and increased flexibility in application timing.

“Farmers want to make sure they have effective weed control to protect yields, so pre-emerge herbicides will be utilized more this year,” said Mark Licht, an Iowa State University Extension field agronomist based in Carroll County.

The more researchers learn about weed control, it becomes clear that weeds must be controlled earlier rather than later, Licht said. When weeds are permitted to thrive early in the season, they steal vital moisture and nutrition from the growing crop.

According to Syngenta, weeds that are allowed to compete with a soybean crop to only the 2-inch stage have already stolen more than 16 bushels per acre.

A residual pre-emergence herbicide for early-season weed control also broadens the application window and holds weed pressure back, allowing more flexibility for post applications, Licht said.

Managing resistance

The wide adaptation of Roundup Ready technology also raises the importance of addressing herbicide resistance in weeds, said a recent survey conducted by ISU. In it, Iowa farmers agreed that glyphosate is effective and provides adequate weed control, although many producers admitted they are using increasing rates to get this control, Licht said.

Most pre-emerge applications will add an additional mode of action to a weed control program, which can help manage resistance issues.

“The message is simple,” said Mike Roegge, a University of Illinois Extension educator. “For the most efficient use of Roundup Ready crops, use a pre-emerge herbicide to reduce the opportunities for weed resistance, as well as give you more time to apply the post emerge glyphosate.”

Roegge also recommends applying the post-emerge application of glyphosate based upon weed size to achieve the highest economic return.

Numerous research projects have been conducted to determine the optimal time to apply post-emerge glyphosate.

“They’ve all shown pretty much the same results,” Roegge said. “Control weeds in corn when they’ve reached the 4-inch stage, and in soybeans when they’ve reached the 6-inch stage. Delaying from these intervals guarantees a yield decrease, because the weeds are much more competitive than the crop is.”

You can contact Darcy Dougherty Maulsby at yettergirl@yahoo.com.

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