Winter weed control in dormant bermudagrass

By |  November 24, 2014 2 Comments

Patrick McCullough, Ph.D., is an extension turf weed scientist at the University of Georgia. He conducts numerous weed control trials each year to help him make weed control recommendations to superintendents. McCullough can be reached at pmccull@uga.edu for more information.

Q: What winter weed control strategy do you recommend for dormant bermudagrass greens?

In Georgia, one application of a preemergence herbicide such as bensulide or oxadiazon in mid or late September, will control the major flush of annual bluegrass (Poa annua) seed germination that occurs from early October to early December. Bensulide or oxadiazon are recommended because they are safer than other preemergence herbicides on ultradwarf bermudagrass.

TranXit (rimsulfuron) or Revolver (foramsulfuron) can be used for postemergence annual bluegrass control later in the winter or early spring. Other postemergence herbicides used for annual bluegrass control on bermudagrass greens should only be used at your own risk.

Q: What strategy do you suggest for a creeping bentgrass green and collar with bermudagrass surrounds?

Use caution when making any herbicide application to dormant bermudagrass surrounds so overspray, drift, tracking or lateral movement of the herbicide doesn’t reach the creeping bentgrass turf. Many superintendents will leave a 20- to 30-foot untreated buffer zone around the creeping bentgrass green and collar to provide a margin of safety.

In recent years, many superintendents have applied Specticle (indaziflam) to the bermudagrass surrounds. Specticle is a good preemergence herbicide and provides good early postemergence control of annual bluegrass, giving superintendents a little more application timing flexibility in the fall. Xonerate (ambicarbazone) can be applied to the untreated buffer between the collar and the untreated part of the surround to control annual bluegrass and other annual winter weeds. Xonerate is fairly safe on creeping bentgrass, so any drift or tracking to the green would be less injurious than most other herbicides used for postemergence annual bluegrass control in
bermudagrass.

Q: What winter weed control strategy works well in dormant bermudagrass tees and fairways?

First, apply a preemergence herbicide in September. A dinitroaniline (DNA) herbicide will work well for this application. Many superintendents in Georgia follow up with a single application of simazine, atrazine or simazine plus glyphosate, as needed, in December to March. These herbicides are inexpensive and provide good control of emerged winter weeds. They control many winter broadleaf weeds and annual bluegrass.

There are a few things to consider when using simazine, atrazine or simazine plus glyphosate in winter. Simazine can be applied when the bermudagrass is nearly dormant, but atrazine and glyphosate must be applied when the bermudagrass is 100-percent brown and dormant, or injury may result that will affect spring green-up.
Another factor to consider is annual bluegrass resistance to simazine and atrazine. On some courses in the South, annual bluegrass biotypes have shown resistance to simazine and atrazine due to their use year after year. In these situations do not use simazine or atrazine alone for postemergence control of annual bluegrass. Tank-mixing triazine herbicides with other modes of action, such as glyphosate, could improve the potential for control if resistance is suspected.

Also, don’t apply Xonerate if you suspect your annual bluegrass biotype is resistant to simazine or atrazine. Xonerate has the same mode of action as simazine and atrazine, and an annual bluegrass plant that is resistant to them will also be resistant to Xonerate.

If annual bluegrass resistance to simazine, atrazine or Xonerate is suspected, consider using sulfonylurea herbicides, Kerb (pronamide), or SureGuard (flumioxazin) for postemergence control. These herbicides have a different mode of action than simazine, atrazine or Xonerate and will improve your potential for success.



2 Comments on "Winter weed control in dormant bermudagrass"

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  1. George Nord says:

    Clark,
    Hey, G. Nord here. (Purdue ’81 Turf Grad). Hope all is well.
    Here’s my question…..We accidentally over applied glyphosate to 95-100% dormant fairway bermudagrass (S. Indiana).
    We applied 96 oz per acre on March 15, 2018. Do you have any experiments your people have done to show what effects this would have on green up or turf kill? We have been lucky I hope since we’ve had cold wet weather following our application.

    Thanks! Boiler Up!!

    George

  2. Danny says:

    Is there anything out there to control or kill
    Virginia Butt?? Nut?? Weed in Bermuda grass??? Natchez Ms
    Thanks

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