A change of seasons is upon us. The leaves are beginning to drop from some trees and the day lengths are getting noticeably shorter. September has brought with it cooler day and nighttime temperatures and average 4-inch soil temperatures even dipped into the high 50’s yesterday. These favorable environmental conditions have allowed existing turf the chance to recover and newly sown seed the opportunity to germinate and begin to cover.
The fall is also a great time to clean up unwanted creeping bentgrass. Because of all the rainfall and submerged conditions we experienced during the summer months, creeping bentgrass had an opportunity to gain a competitive advantage and may have spread into areas where it wasn’t present before. Luckily, creeping bentgrass can be controlled with Tenacity herbicide.
Tenacity is a systemic herbicide with pre- and post-emergence activity on many grass and broadleaf weeds. Tenacity is also capable of selectively removing creeping bentgrass from Kentucky bluegrass, perennial ryegrass, tall and fine fescue. Multiple applications of Tenacity are required for complete control of creeping bentgrass.
Tenacity works by inhibiting HPPD enzymes which aid in the synthesis of carotenoids. Carotenoids help to protect the plant from excess light energy received from the sun. Without these protective carotenoids, the excess energy causes new growth to turn “bleach” or turn white and eventually kills susceptible plants.
I have done quite a bit of work with Tenacity. Below are some pictures from my research and from golf courses who have used the product.
| Plot of turf adjacent to a creeping bentgrass putting green after recieveing one application of Tenacity herbicide. The bentgrass (susceptible) turns white, while the Kentucky bluegrass remains unaffected. |
| Here, Tenacity was applied to an intermediate cut of Kentucky bluegrass to clean up creeping bentgrass that had invaded from the fairway. Bleaching of the bentgrass appears after just 1 application. |
| Applying tenacity next to monostands of creeping bentgrass needs to be done with caution. Here, spray drift from the adjacent treated turf caused bleaching symptoms on a creeping bentgrass green. Bentgrass will not be completely controlled after one application but the “bleaching” symptoms can be unsightly in the wrong spot. |
| Multiple applications of Tenacity are needed for complete control of bentgrass. Here, three applications have killed the majority of creeping bentgrass in a stand of Kentucky bluegrass. |
For more information about Tenacity herbicide and its various uses visit the Syngenta Tenacity page.
Have creeping bentgrass in your yard? Read how Harold Enger, our lawn care expert, tells a reader the three best ways to eliminate it.
“I have question about creeping bent grass. It’s all over my lawn in splotches. I watched your video about it but you didn’t mention what I could use to get rid of it. Help! I just want a gorgeous lawn and am at a loss with it. Thanks in advance.”
Thank you for sending in your question. Controlling bentgrass can be a daunting task. My recommendations are based on the assumption that your lawn is composed mostly of bluegrass, ryegrass or turf type tall fescue. If you have other varieties of grass in your lawn, please let me know and I can provide you with recommendations to use for those grasses.
Dealing With Bentgrass – Expert Lawn Care Advice
There are three ways you can get rid of creeping bentgrass:
First method is to spray the individual spots with a non-selective herbicide like Round-Up.
This will kill off the bentgrass, but it will also kill the desired grasses, so only spray where the bentgrass is growing. You should spray about 6 inches beyond the patches to make sure you control the stolons, or above-ground runners, that may spread out into the lawn, but are often not visible. It will require two applications. Once the grasses die, you can either reseed or re-sod the spots. The best time to use Round-Up is when the grass is actively growing and not under heat or drought stress.
