The Enid News and Eagle, Enid, OK

October 5, 2013

Weeds have a start on wheat in some areas

By Roger Don Gribble, Extended Forecast
Enid News and Eagle

ENID, Okla. — Wheat producers are evaluating their stands and determining plans for the 2014 harvested wheat crop.

Producers have had above-average moisture conditions, but it’s been dry in a few locations. In a few areas, wheat has yet to emerge or be planted. What are emerging are some annual grassy weeds in the planted crop. Cheat, ryegrass, rescuegrass, downy brome, rye and jointed goatgrass have emerged and are off and running ahead of wheat.

Depending on where you are standing in northwest and north central Oklahoma, the weed species will be different. There seems to be more jointed goatgrass west and north of Enid and more rescuegrass to the west and south of Enid. For everyone else, far and away downy brome seems to be the species of highest density.

Over time, herbicides such as Olympus, Olympus Flex, PowerFlex, Finesse Grass and Broadleaf, Maverick and Beyond have done an excellent job of controlling cheat, but have been weak on downy brome control.

Most herbicides have been applied in the spring with a topdress application of nitrogen. In the spring, we have limited success with trying to control downy brome, so producers have allowed downy brome to become a much more populated weed in wheat. Downy brome matures much earlier than our other weedy grasses and will shatter more seed onto the ground, so rarely would producers receive a dockage figure at harvest.

There are a couple of suggestions that could be made to reduce the yield loss to downy brome. The first would be the use of crop rotations. The work done at the North Central Research Station at Lahoma indicates less grassy weeds where the three crop in two years rotations have been implemented. It seems the herbicides used in either the summer crop rotation or those used as the rotation moves to the double crop behind wheat, there is a reduction in the downy brome species. When the rotation moves back to wheat, we have not needed a weed control product for downy brome. These experiments are working with a no-tillage system, but tillage also is an excellent option for controlling downy brome.

As a second option and more targeted to producers in continuous wheat production would be the herbicide technologies currently used.

The slight adjustment would be to move that herbicide application into the fall of the year rather than the traditional spring season. This holds true with our usual cheat control products mentioned earlier. Not only is our cheat control better in the fall applications, but our downy brome control also is greatly improved. Not always, but usually, we see an improved yield from wheat when weed competition is reduced with the fall herbicide applications.

As always, weed control of grassy weeds is better when both the wheat and the weeds are actively growing. Since moisture conditions are more favorable than in previous years and planting and emergence of the crop are going well, scout your fields and if needed, plan a grassy weed control application in the late October to early November timeframe.

Please contact your Oklahoma Cooperative Extension Service ag educator located in your county for additional information on weed control in wheat.

Gribble is Oklahoma Cooperative Extension Service northwest area agronomist.