Arkansas weed control: Check wheat for ryegrass, cheat

Scout closely now for both ryegrass and cheat in wheat. If you have a problem and want to control it, now is the time.

I get a lot of calls about both weeds in the spring when it is too late to do anything about them.

If you have a ryegrass problem and have no reason to suspect that it is Hoelon-resistant, it is much easier to control with Hoelon or Achieve now while it is small, and often you can use lower rates in the small ryegrass. I have always done as well with 1.33 pint per acre of Hoelon applied from mid-November to mid-December, as I have with the higher rates applied at the same timing.

The 1.33 pint-per-acre rate applied mid-November to mid-December has been much better than higher rates applied in the spring.

In a lot of work with Hoelon, we have never gotten any consistent increase in control by adding either surfactants or crop oils.

With Achieve, I usually just use 0.6 pound per acre (of 40 DF product) and add the Super Charge adjuvant as recommended.

If you have Hoelon-resistant ryegrass, I hope you used Finesse as a pre-emergence treatment as I discussed in recent articles. If you did not and you have the problem, our research indicates that the rate of 3 ounces per acre of Sencor applied to two- to three-leaf wheat, followed by a labeled rate for your soil texture at the two- to three-tiller stage, will allow you to make a crop.

Results with this treatment have been quite good. Be sure you have a variety with good Sencor tolerance.

If cheat is your problem, Sencor is the only effective herbicide available. You have the option of using the rate of 3 ounces per acre at the two- to three-leaf stage of wheat growth or the labeled rate (from 0.25 to 0.5 pound per acre, depending on soil types) at the two- to three-tiller stage.

As long as we have used a wheat variety with good tolerance, wheat injury has never been a problem in our trials. We have had no more injury with the low rate at the early timing than with the high rate later.

The weed control for the low rate applied early has often been better than weed control with the later application.

The problem we had controlling cheat with Sencor is it was too big by the time the wheat got to the tillering stage. The low rate applied early allows you to hit it when it is in the two- to three-leaf stage of growth. Do not add any type of adjuvant, surfactant or crop oil to the Sencor.

Proper identification is necessary if you are to get good weed control. Spotting a problem is easier in drilled wheat than in broadcast wheat. Field history can be one of the most important weed ID tools.

Ryegrass is easy to identify. It seldom occurs in scattered infestations. It will usually be thicker than “hair on a dog's back” if it is there. It is also very slick, smooth, and shiny, and usually it is red at the base.

Cheat is much more difficult to distinguish from some other of the junk grass like little barley. It will be pale green and very hairy or fuzzy. I will admit I have trouble identifying it.

Field history should really be taken into account with cheat. If you had a cheat problem the last time the field was in wheat, that is likely what it is.

Ford Baldwin is an Arkansas Extension weed scientist. e-mail: [email protected].

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