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4 points to ponder for 2014 corn

If growing corn were akin to being a student, you’d be nervous now because final exam time is quickly approaching. The results of your corn-growing strategies will soon become apparent from your combine cab.

While you’re harvesting this fall, scan from the bird’s-eye view of your cab for any problems that have surfaced this year. Lessons learned can help you plan 2014 strategies. Following are four points to look for this fall.

1. Analyze weed escapes

Corn has an edge on soybeans in that its early canopy can halt many weed escapes. Still, watch for escapes in drowned-out spots and skips. These areas may consist of weeds that didn’t get sprayed. However, escapes may be due to herbicide resistance. Areas void of crop competition give weeds like glyphosate-resistant waterhemp room to thrive and multiply.

“Last year, I was able to see firsthand, for the first time on my farm, true resistance to glyphosate,” says Pat Duncanson, a Mapleton, Minnesota, farmer. “I had some waterhemp I wasn’t able to control. I ended up doing some hand-weeding to slow the progress of this weed and to keep it manageable as a small problem. It changed my attitude overnight; it was no longer a problem that would happen someday.”

2. Critique Your Weed Control  

Everyone likes to see a clean field at harvest. Still, this might not be a true indicator of weed-control success. Waiting too long to control weeds can ultimately rob your crop of yields, even if you kill them with postemergence herbicides.

That’s why weed scientists and agronomists are big fans of preemergence residual herbicides. They nix weed growth right at the outset of the cropping year.

Unfortunately, Mother Nature often had other plans during last spring’s soggy weather. Some of you likely couldn’t apply them in waterlogged fields. For those of you who could, though, preemergence residual corn products probably curbed waterhemp until the corn canopied.

“Multiapplication timing using preplant herbicides along with Roundup Ready or Liberty Link technology can control weeds that germinate at different times,” says Mike Owen, Iowa State University (ISU) Extension weed specialist.

Including preemergence residual herbicides can snuff weeds before they start. Weeds even as early as

V2 corn can slice yields by 5%, according to 2008 ISU trials.

3. Think about next year’s hybrids

Picking the right genetics can boost your bottom line more than any other input. “That is the engine,” says Jeff Hartz, marketing director for Wyffels Hybrids. “Then, you find the right trait platform.”

Harvest is a good time to determine which hybrids worked and which did not.

“If someone came to me with a great genetic corn that was non-Roundup resistant, it would be difficult for me to use,” says Duncanson. “So, I first look at genetics, but then I also look at the trait package. Most of the time, I can get the trait package in the genetics I want. Picking the right genetics in the right trait package could be the cheapest input on a per-acre basis,” he says.

4. Monitor corn rootworm resistance

Downed corn that you eye from your combine cab could signal myriad maladies. One unfortunate possibility may be rootworm-trait failure. ISU researchers first confirmed corn rootworm resistance to the Cry3Bb1 protein contained in Monsanto’s Yield Gard hybrids in 2011. Since then, it was confirmed in Illinois in 2012, with performance problems also surfacing in Minnesota, Nebraska, and South Dakota.

It’s important to note that the trait still works in most cornfields. Rootworm resistance has not surfaced in Herculex RW hybrids containing the Cry34/35Ab1 protein or in the Agrisure RW trait containing the mCry3A protein. However, repeated use of the same control measure in the same crop can inevitably lead to resistance, just as it has with herbicide-resistant weeds.

Following are four steps you can take to forestall corn rootworm resistance to traits.

  1. Rotate to soybeans. “The number one way to control resistance is to reset the clock,” says Chuck Kolbet of Monsanto. Planting soybeans breaks corn rootworm life cycles in many areas. That isn’t the case, though, for regions struggling with extended diapause or the western corn rootworm variant. In these situations, corn rootworm has outfoxed the corn-soybean rotation.

  2. Rotate corn rootworm-resistant traits. “If you use the same product several years in a row in the same crop, you can get resistance,” says Bruce Hibbard, USDA-ARS entomologist based in Columbia, Missouri. Farmers can also fend off resistance by planting pyramided trait packages containing multiple Cry proteins. If one mode of action fails, another control mode contained in the pyramid can curb rootworm.

  3. Apply soil insecticides. “Granular soil insecticides banded over the row are the only control measure that corn rootworm has not resisted,” says Hibbard.

  4. Select naturally tolerant rootworm hybrids. “Some hybrids naturally have bigger root systems,” says Hibbard. “If rootworms emerge, more roots enable them to better endure rootworm feeding.”

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