Weed Science 101: Making new technologies work: Part III

It may take cotton growers a while to get used to spraying one- to two-leaf cotton with 2,4-D. But that’s what producers will need to do with the new Enlist Duo herbicide if they are to use the new technology successfully.

Researchers at the Northeast Research Station showed farmers the results of spraying the new Roundup Ready Xtend and Enlist cotton and soybeans with dicamba and 2,4-D at the its annual field day. (Note: Enlist cotton has not been deregulated, but researchers received a variance that allowed them to plant and spray the crop and destroy it after the field day.)

“We sprayed the Enlist cotton with 75 ounces of Enlist Duo herbicide per acre early post,” said Donnie Miller, weed scientist and resident director at the station. “The cotton was about one- to two-leaf. It took out the initial flush that came out; reduced the competition we had; and you can see how good the cotton looks.

“Now it’s ready for us to come in and make another application – one that we would have already made if this was a normal production field (and not crop-destruct),” Dr. Miller said. “But I just wanted to show how good a jump we can get the cotton with an early application and limit that competition.”

Dr. Miller said the new technologies provide good control of a broad spectrum of weeds in cotton and soybeans that contain the Roundup Ready Xtend and Enlist traits. But early weed control will continue to be important.

“Weed competition starts early so we want to jump on it early,” he said. “As I said these technologies are going to conform to the principles of weed science, and they’re going to limit competition only when you get them out there early enough.”

The researchers delayed applications in some of the plots by 10 days, Miller said. Those 10 days had an impact on the height of the cotton.

“The first treatment we put out the weeds were small, and we cooked it within five days,” he said. “Everything was brown out here. In this plot, we waited – we sprayed this about seven days ago – and this barnyardgrass is purpling and it may or may not die. So you have to make these applications when weeds are small.”

How small should they be? “We’re talking small, very small,” says Dr. Miller. “Four inches is a big pigweed.”

To learn more about the LSU AgCenter and its Extension and research facilities, go to http://deltafarmpress.com/government/lsu-agcenter-escapes-major-budget-cuts-thanks-rural-legislators.

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