Corn Growers to Have New Herbicide

In recent years North Dakota crop producers have been offered at least one new active ingredient per year for weed control. For 2011 it was saflufenacil, commonly known as Sharpen. It has become a popular herbicide for use in chickpeas, field pea, small grains and other crops. Sunflower growers can use it as a harvest aid/desiccant. In 2012 Bayer released thiencarbazone. It is a relative of flucarbazone (Everest 2.0) and propoxycarbazone which is contained in Olympus and Rimfire Max. Thiencarbazone is not a stand-alone product. For wheat it was combined with bromoxynil and pyrasulfotate giving excellent grass and broadleaf weed control.

For 2013, corn producers will have pyroxasulfone by Kumiai. It has the same mode of action as Dual and Outlook. It is a soil applied herbicide so it can be applied in the fall, early pre-plant, and pre-emergence. It will have some early post application for residential weed control. It controls many grass and broadleaf weed using less product than Dual and Outlook. The key value of this product is that it provides 6 to 10 weeks of activity. Three different companies will market pyroxasulfone. BASF will offer it under the name Zidua. Valent will market it as Fierce which will also contain Valor. FMC’s product is named Anthem and also contains Cadet. Registration of pyroxasulfone is pending on soybeans but has been completed for use on corn.

Pyroxasulfone has good control on foxtails, Japanese Brome, wild oat, pigweed, lambsquarter, nightshade, velvetleaf, waterhemp, kochia, buckwheat and Russian thistle. It is weak on broadleaf weeds that have large seeds like ragweed, cocklebur, wild sunflower and marshelder.

There are some carryover restrictions. It will be okay to plant corn or soybeans the following year but there will be a month restriction for all other crops. Once pyroxasulfone is cleared for registration on soybeans, which is expected later this year, crop rotation restrictions will be modified to be less restrictive on sugarbeets, canola, and possibly others.

Researchers at NDSU, over a 7 year period, have used rates ranging from 2 to 7 ounces of pyroxasulfone active ingredient (AI) per acre. The label on commercial products listed above will state a maximum of 4.25 ounces AI per acre so Rich Zollinger, NDSU Extension Weed Control Specialist, recommends using the highest rate allowed by the label for good, consistent control.

A downside of pyroxasulfone, anyway for western North Dakota, is the need for substantial rain to activate the herbicide. Zollinger has found multiple rain events will increase the activation. One inch or more rainfall is preferred. Zollinger indicates we could see pyroxasulfone registered on other crops including sunflower, safflower, pulses and potato.

Another new herbicide for 2013 is aminochlopyrachlor. It will be added to the previously popular herbicide named Glean. This new combination will be named Perspective. However, its registration will be for non-cropland only to control noxious and invasive weeds including leafy spurge.