Georgia growers emphasize weed control in wheat

With interest in wheat production in the Southeast running at an all-time high, many growers are paying more attention than usual to practices such as weed control that’ll help guarantee higher yields.

In Georgia, producers have especially shown interest in the wheat herbicides Prowl H20 and Axiom, says Stanley Culpepper, University of Georgia Extension weed Scientist.

Prowl H20, says Culpepper, can be applied to wheat postemergence at 1.5 to 2.5 pints per acre as long as the wheat is between the first leaf stage and the flag leaf being visible.

“Prowl does not control emerged weeds but can provide residual control of sensitive weed species if the herbicide is activated by rainfall or irrigation in a timely manner,” says Culpepper.

Data on Prowl’s ability to control broadleaf weeds like henbit, chickweed, etc., is currently limited with hopes of generating more data this winter, he adds. The Prowl H20 label does allow for mixtures with any labeled postemergence herbicide for wheat.

Culpepper says he believes the following are the two greatest uses for Prowl H20:

• First, a mixture of Prowl H20 with a postemergence (Hoelon, Osprey, Axial) annual ryegrass herbicide. In theory, with this application, the postemergence herbicide would control the emerged ryegrass and the Prowl H20 would provide residual control. However, it is worth mentioning that most ryegrass growers see at harvest is not ryegrass emerging after the postemergence herbicide treatment, but rather from ryegrass that was not controlled with the postemergence herbicide because the ryegrass was too large when treated. Prowl H20 will not help in this situation.

• A second use for Prowl H20 in wheat would be in a situation where the wheat emerges while the ryegrass is late to emerge. Growers could apply the Prowl H20 over one-leaf wheat and if activated by rainfall or irrigation, it would provide residual control into the season improving the likelihood of making “timely” postemergence applications.

Finally, says Culpepper, after years of section 18s and enormous efforts by Bayer CropScience, the EPA, and the Georgia Department of Agriculture we finally have a label for Axiom in wheat but for wheat only.

For 2007, the availability of this product and the application timings limited its use. “However, this product will play a very important role in 2008 by providing a herbicide with great broadleaf activity and most importantly provide a herbicide with an alterative mode of action, thereby delaying the resistance of ryegrass to all postemergence ryegrass herbicides, including Hoelon, Axial and Osprey,” he says.

Growers wanting to use Axiom need to review the label very carefully, says Culpepper. “First there are specific cultivars that are listed on the label as being tolerant. Secondly, the application rate varies greatly based on soil type. Most Georgia growers will be using 6 to 8 ounces of the product per acre, but again this should be determined from the label. “Axiom should be applied in wheat from the spike stage up to the three-leaf growth stage. If used properly, the herbicide can provide excellent control of radish, henbit and chickweed,” he says.

Ryegrass control by Axiom will vary based on its stage of growth at application timing, notes Culpepper. “If the application to wheat is during the spike wheat stage and this is prior to ryegrass emerging — assuming herbicide activation by rainfall or irrigation — good ryegrass control can be noted. However, if the ryegrass is emerged at the time of application, control will be much less,” he says.

Culpepper reminds growers to review rotational restrictions before using Axiom.

e-mail: [email protected]

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