Are you seeing a different type of grass growing into your lawn? One of the most problematic weeds a good number of homeowners encounter is unwanted bermudagrass or centipedegrass that will aggressively invade a zoysia lawn. You may notice this around the edges of your lawn, where your yard borders with a neighbor’s yard or even in a few bare spots in your lawn. There are a few tried and true methods that will get rid of these unwanted grasses, however, it should be noted that the best way to get rid of these grasses is to choke them out with a healthy lawn or use an herbicide to spot treat small invasions. Read on to learn how to kill bermuda grass in zoysia.
How Bermudagrass and Centipede Spread
Bermudagrass spreads with the use of both stolons and rhizomes while centipedegrass spreads with just stolons. A stolon is an above-the-ground stem that creeps along the surface of the soil and subsequently grows a clone of the original plant on the end of it. The clone plant then sends down roots and establishes itself as an independent plant before repeating the process. Rhizomes, also called “creeping rootstalks” or just “rootstalks”, are modified stems that run underground horizontally, often just underneath the surface of the soil. Rhizomes strike new roots downward into the soil and also shoot stems upwards. You can learn more in What are Stolons and Rhizomes?.
Although the image above demonstrates St. Augustine grass spreading, it shows how an above-the-ground stolons spreads across the soil to different areas around it.
You may not see bermudagrass in your lawn, but it is still common for homeowners to spot a bermudagrass seed head in the middle of their lawn. This indicates that bermudagrass is spreading with the use of its rhizomes underneath the soil’s surface.
Pictured above: A bermudagrass seed head.
With that being said, it may be difficult to distinguish if bermudagrass is creeping into your lawn at all. A helpful tip is to wait until the early morning when a lot of dew has accumulated on the leaves of grass. This magnifies the look of bermudagrass blades. If you take a look at the images below, you will see how morning dew really makes bermudagrass stand out in your lawn.
Pictured above: Dew on bermudagrass that has invaded different areas of zoysia landscapes.
Choke Out Weeds With a Healthy Lawn
The best way to control bermudagrass, centipedegrass or any other type of weed in your lawn is to have a strong, thick turf to begin with. A strong turf will outcompete weeds and keep them from showing up. This comes in time with appropriate cultural methods such as proper mowing heights, an appropriate irrigation schedule and a fertilizer regimen. According to our Zoysia Homeowner Maintenance Guide, you should keep your zoysia between .5–2 inches in height throughout the year. Zoysia also requires about one inch of water per week including rainfall. Be careful not to overwater your grass as this will promote the possibility of disease.
A regular fertilizer regimen will also keep your zoysia full of the nutrients it needs to stay strong and healthy throughout the different seasons of the year. Sod University recommends Lawnifi®, a fertilizer program that uses Catalyst TechnologyTM to send nutrients to your lawn and other plants efficiently. It consists of three individual fertilizer boxes for each of the active growing seasons: spring, summer and fall. Each box also contains three separate bottles of fertilizer with differing nutrient ratios. Lawnifi also has a granular formula, Lawnifi Foundation, for those who prefer granular fertilizer. Learn more about Lawnifi by reading our Why Use Lawnifi Fertilizer? blog on Sod University. Sod Solutions also offers homeowner maintenance guides for your EMPIRE® Zoysia, Geo® Zoysia and InnovationTM Zoysia.
Other useful tips that may help you are using mulch to choke out bermudagrass and centipedegrass by preventing it from reaching any sunlight, or filling in any bare spots with zoysia grass plugs. Bare spots may be caused by shade or disease, but either way, they provide opportunity for weeds and other unwanted grasses to invade because there is no competition for soil space. Filling those spots in with other plants helps your grass further outcompete unwanted weeds.
How to Kill Bermuda Grass in Zoysia Lawns
Sometimes, in more extreme cases, there is nothing left to do but use chemicals to fight off the unwanted grass. It is important that you apply an herbicide during the right time of year, however. Applying herbicides in the summer, specifically when temperatures exceed 85 degrees, isn’t recommended because it will burn your lawn and damage your grass. You can read more about this in The Best and Worst Times for Herbicide Applications.
There are two general types of herbicides: selective and non-selective. A selective herbicide treats the weeds it is labeled to treat. A non-selective herbicide will kill any plant it comes in contact with—including your grass—so be careful with these. If you have a zoysia lawn, selective herbicides that contain the active ingredients fenoxaprop or fluazifop will treat the bermudagrass and centipede without damaging your lawn if it is applied properly. A suggested herbicide a lot of specialists recommend for bermudagrass and centipedegrass invasions is Fusilade II Herbicide.
Spot Treating with a Non-Selective Herbicide
As previously mentioned, a non-selective herbicide will kill any plant it comes in contact with. This includes your grass or other nearby plants in your garden. Popular non-selective herbicides contain the active ingredient glyphosate. If you choose to use a non-selective herbicide, you will also want to apply it while walking backwards out of the sprayed area. If you walk through areas where you’ve applied the non-selective herbicide, you may get it on your shoes and leave footprints throughout the rest of your lawn. If you don’t like the idea of using glyphosate as a non-selective herbicide, you may find our blog on Alternatives to Glyphosate for Weed Control useful.
Pictured above: An image demonstrating what it looks like to walk through a lawn with glyphosate on a homeowner’s shoes.
For more information on weed control, read our Weed Control blog or our popular article on Identifying Common Lawn Weeds. Sod University also has a blog on How to Keep St. Augustine Out of EMPIRE Zoysia Lawns. Although this blog specifically discusses removing St. Augustine from EMPIRE, the same tips and tricks can be applied to all zoysia grass.