Quackgrass Control in Turfgrass
by Ron Calhoun, Michigan State University Extension Department of Crop and Soil Sciences, originally posted on May 5, 2006
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Everyone has their favorite weed that they struggle to control in turf, but when it comes to the really tough to control weeds, quackgrass often tops the list. The first step in controlling any pest is proper identification and there is no better place to start identifying turf weeds than with the resources at: www.msuturfweeds.net.
Once you’ve identified that quackgrass is your weed of interest, there are several options for trying to discourage, remove or eliminate it from turf.
Option 1: Management
Many folks have effectively “eliminated” quackgrass by masking its presence in the lawn. This is usually accomplished by increased nitrogen fertilization and increased mowing frequency. (Just what everyone wants, mowing more often!) This approach has been implemented with relative success by more than a handful of turf managers. The idea is that the quackgrass only has a competitive advantage when the desirable grass sits idly by. By increasing the vigor of your lawn you will choke the quackgrass, make it darker green and, for the most part, make it disappear. This method could be accomplished by fertilizing your lawn with 0.25 to 0.5 lbs. N\1000 sq. ft. every two weeks during the growing season. If this ends up being one of those dry summers, you would definitely want to suspend this program because unless you’re irrigating, the turf will not be able to use the nitrogen. If you follow this program, you will notice that the quackgrass patches are much smaller next spring.
Option 2: Mechanical removal
Due to the perennial nature of quackgrass and its well-developed rhizome system, it is very difficult to remove by mechanical means. Methods include digging up the offending patches, including several inches of soil and replacing with new topsoil and reseeding. However, the rhizomes of quackgrass can grow 6 to 8 feet deep in the ground, and these rhizomes could potentially “push” new plants to the surface.
Another option is solarization. This method uses clear plastic fastened securely to the ground over the quackgrass areas. Be sure to cut the plastic slightly larger than the patches. Leave the plastic in place for five to seven days in the spring or summer when the weather is nice. The plastic will help trap the heat close to the soil surface and hopefully devitalize the plant material. After removing the plastic, you may reseed the area.
Option 3: Non-selective chemical removal - Roundup!
Use a non-selective herbicide like Roundup to kill the patches. Keep in mind that non-selective means that it kills whatever plant it touches. This method will create dead patches in your lawn that can be re-established. In our opinion you will need to apply the Roundup twice. Make the second application 14 days after the first. Seven days after the second application you can rough up the area and sow your new grass seed.
Option 4: Selective chemical removal
If your lawn is primarily Kentucky bluegrass, there is a selective herbicide that will remove the quackgrass without killing the rest of your lawn. This product is only available to professional lawn care operators, and they need to make two applications on a 14-day interval. The name of the product is Certainty.
Option 5: Do nothing
Obviously quackgrass is green and takes mowing. You may decide after looking at the other options that it is better than bare soil.