How to Get Rid of Bermuda Grass in Zoysia

Bermuda grass creeping into a zoysia lawn is one of the most frustrating warm-season turf problems because both grasses share similar growth habits, similar color, and similar tolerance to many herbicides. The most effective approach is repeated applications of a grassy-weed herbicide called fluazifop, ideally tank-mixed with triclopyr, timed to early spring or early fall when bermuda grass is actively growing but vulnerable. Even with the best chemical program, expect the project to span two or more growing seasons before bermuda grass cover drops to acceptable levels.

Why Bermuda Grass Is So Difficult to Kill in Zoysia

Both bermuda grass and zoysia are warm-season, perennial, spreading grasses. They green up around the same soil temperatures, go dormant at roughly the same time, and share enough physiology that most broad-spectrum turf herbicides either kill both or spare both. A product that targets “grassy weeds” in cool-season lawns will often damage zoysia just as badly as bermuda grass, which is why the standard advice for cool-season turf does not transfer here.

Bermuda grass also has an aggressive underground rhizome system. Even when top growth is visibly scorched by a herbicide, the rhizomes can store enough energy to push new shoots weeks later. Research has confirmed that turf managers dealing with bermuda grass contamination in zoysia will likely need applications over multiple years because bermuda grass keeps regenerating from those deep rhizomes.¹ This is not a one-and-done project.

The Go-To Herbicide Combination

The chemistry that works best belongs to a class of herbicides called ACCase inhibitors, sometimes referred to by the abbreviation AOPP (aryloxyphenoxypropionates). Of these, fluazifop-P-butyl (sold under names like Fusilade II and Ornamec) is the most widely studied for bermuda grass removal in zoysia. It can provide selective grass-weed control with limited injury to zoysiagrass.² Fenoxaprop (the active ingredient in Acclaim Extra) is a close second in the same herbicide class.

On their own, these herbicides give moderate bermuda grass control. When fluazifop, fenoxaprop, or similar AOPP herbicides were applied alone in trials, bermuda grass control ranged from roughly 40 to 70 percent, and turf coverage of the bermuda grass still sat between about 18 and 50 percent.³ That is decent suppression, but not the kind of result that makes bermuda grass disappear from your lawn. The real gains come from adding triclopyr to the tank mix.

Why Triclopyr Changes Everything

Triclopyr is a broadleaf herbicide (commonly sold as Turflon Ester). It does not kill bermuda grass by itself in the way it kills clover or dandelions, but it does something unusual when combined with fluazifop or fenoxaprop: it both increases bermuda grass suppression and decreases injury to your zoysia. In trials, adding triclopyr to the AOPP herbicides bumped bermuda grass control into the 64-to-79 percent range and reduced bermuda grass turf coverage to as low as 8 percent. Meanwhile, zoysiagrass injury dropped to between 1 and 18 percent with the tank mix, compared to higher injury when the AOPP herbicides were used alone.³

Multiple research groups have confirmed this synergy. Work out of Arkansas and Alabama found that fluazifop plus triclopyr provided more bermuda grass suppression than fenoxaprop plus triclopyr, and both mixes outperformed the AOPP herbicides applied on their own without reducing zoysiagrass quality.⁴ Separate research confirmed that triclopyr safened fluazifop and fenoxaprop on zoysia turf without decreasing bermuda grass suppression compared to either herbicide alone.⁵

If you take one thing from this article, it should be this: do not spray fluazifop or fenoxaprop alone if you can help it. The triclopyr tank mix is the standard recommendation across the turfgrass research community for good reason.

When to Spray

Timing matters as much as product selection. Research tracking bermuda grass suppression at different points in the growing season found that early-spring and early-fall applications were far more effective than spraying in the middle of summer. Applications made in late spring and midsummer suppressed bermuda grass only about 4 to 57 percent at six weeks after treatment, depending on the year. In contrast, early-spring and fall applications suppressed bermuda grass by 90 percent or more at five weeks after treatment.⁶

The early-spring window is when bermuda grass is just breaking dormancy and pushing new growth but has not yet built up a full canopy. The fall window catches bermuda grass as it begins to slow down, channeling energy into its rhizomes and stolons, which makes herbicide uptake more consequential. Spraying during peak summer heat, when bermuda grass is growing at full throttle, produces weaker results because the plant can outgrow the damage.

Zoysiagrass injury from the fluazifop-triclopyr combination stayed below 25 percent across all tested timings and dropped to nearly zero by five weeks after treatment.⁶ So there is a comfortable margin of safety for zoysia at the timings that actually work.

A Practical Spray Schedule

A two-year program is the minimum realistic timeline. In one of the earliest and most-cited trials on this problem, a mixed stand that started at about 35 percent bermuda grass and 65 percent zoysia was treated with fluazifop in mid-May followed by a lighter application one month later, repeated the following year. After two years, bermuda grass cover had dropped from 35 to 7 percent and zoysia had increased from 65 to 85 percent. A fenoxaprop program applied monthly for four applications per year over the same two years produced similar results.⁷

Turf quality did drop immediately after each treatment, but the zoysia recovered and the treatments did not cause permanent damage.⁷ That temporary ugliness is one of the biggest reasons homeowners abandon the program too early. Expect your lawn to look rough for a few weeks after each application. The zoysia fills in, the bermuda grass does not, and the balance gradually shifts.

For most homeowners, a reasonable schedule looks like this:

• Year 1, early spring: Apply fluazifop plus triclopyr when bermuda grass has just started to green up and is actively growing. Follow with a second application about four weeks later.
• Year 1, early fall: Apply a third round as temperatures start to cool and bermuda grass growth slows.
• Year 2: Repeat the same pattern. Assess bermuda grass cover going into Year 3 and decide whether another round is needed.

Three sequential applications per year is the most common trial design in the research, and adding triclopyr to every application is consistently shown to produce the best balance of bermuda grass kill and zoysia safety.

Your Zoysiagrass Cultivar Makes a Difference

Not every zoysia variety tolerates these herbicides equally. Screening of 27 zoysiagrass lines found that the dose required to cause 50 percent injury varied by more than tenfold between the most-tolerant and most-susceptible lines.⁸ That is a huge spread, and it means the same spray rate that barely bothers one zoysia cultivar can hammer another.

The cultivar that consistently shows up as a problem in the research is ‘Diamond’ zoysiagrass. Diamond is a fine-textured variety popular on golf greens and high-end lawns, but it was not tolerant to any of the AOPP herbicides applied alone or tank-mixed with triclopyr, with one narrow exception: fluazifop alone caused only about 18 percent injury and maintained 93 percent turf coverage on Diamond.³ If you have Diamond zoysia, your options are more limited and you should test any herbicide on a small patch before committing to a full lawn application.

Coarser-textured cultivars like ‘Palisades’ and ‘Zenith’ showed the strongest tolerance, with injury ranging from only 1 to 18 percent and turf coverage holding at 84 to 86 percent when AOPP herbicides were combined with triclopyr.³ ‘Meyer’ zoysiagrass, one of the most common home-lawn cultivars, is also well-studied and generally handles the fluazifop-triclopyr combination without lasting damage.

Cultural Practices That Tilt the Fight Toward Zoysia

Herbicides do the heavy lifting, but what you do between sprays affects whether your zoysia can reclaim the ground bermuda grass gives up. Two management choices are especially worth getting right: fertility and mowing.

Nitrogen fertilizer seems like it would help your zoysia grow thicker, but the timing and rate need care. Research found that applying nitrogen fertilizer along with the plant growth regulator trinexapac-ethyl (Primo Maxx) actually reduced bermuda grass suppression. In particular, Tifway bermuda grass spread was greatest when nitrogen was applied at moderate rates along with trinexapac-ethyl.⁹ The takeaway: if you are actively spraying to remove bermuda grass, avoid heavy nitrogen applications right around treatment times. Feed your zoysia after the bermuda grass has taken its hit and the zoysia is filling in.

Mowing height also gives you a subtle lever. Zoysia generally handles shade and lower light better than bermuda grass. Maintaining your zoysia at its preferred mowing height, which for most home-lawn cultivars is between 1.5 and 2.5 inches, keeps the canopy dense enough to shade out bermuda grass seedlings or new stolons trying to creep in from neighboring areas. Bermuda grass is a full-sun species that struggles when it cannot get enough light, so a thick zoysia stand is its own form of suppression once you have knocked the bermuda grass back chemically.

Herbicides to Avoid on Zoysia During This Process

Several products that seem like they should help will actually devastate your zoysia. Research into herbicide applications during the post-dormancy transition period found that glufosinate, glyphosate, diquat, and metsulfuron all caused unacceptable injury to Meyer zoysiagrass when applied while the grass had only about 5 percent visual green cover in early spring. Glufosinate was the worst offender, causing injury levels of 83 percent in one year and 57 percent in another.¹⁰

Glyphosate (Roundup) deserves special mention because homeowners frequently reach for it as a bermuda grass killer. In a mixed zoysia-bermuda lawn, non-selective glyphosate at full strength kills both grasses. At very low, sub-lethal rates, glyphosate can reduce plant height and shoot growth in both bermuda grass and zoysia, but the margin of selectivity is razor-thin. Research found that glyphosate rates up to about 45 grams per hectare for bermuda grass and 90 grams per hectare for zoysia decreased growth without killing the plants, but those rates are a fraction of the standard label rate and extremely difficult to calibrate accurately in a backyard setting.¹¹ This is a technique that has been explored in research but is not practical for most homeowners.

The herbicide 2,4-D, commonly available in broadleaf weed killers, is not effective on bermuda grass. Trials found that bermuda grass showed very mild symptoms from 2,4-D that faded to nearly zero by six weeks after application.¹² Broadleaf-only herbicides will not touch your bermuda grass problem.

What About Sulfonylurea Herbicides

You may come across sulfonylurea-class herbicides like flazasulfuron (Katana) or trifloxysulfuron (Monument) recommended for weed control in warm-season turf. These products are labeled for use on both bermuda grass and zoysiagrass, meaning they are safe on both. That makes them useful for controlling sedges, certain broadleaf weeds, and some annual grasses in a zoysia lawn, but they will not selectively remove bermuda grass from your zoysia because bermuda grass tolerates them just as well as zoysia does. Do not confuse “safe on bermuda grass” with “kills bermuda grass.” The sulfonylureas are not the right tool for this particular job.

The Nuclear Option and When It Makes Sense

If bermuda grass has taken over more than half your lawn and the zoysia is thin, the herbicide-suppression approach might not be worth the years of effort. Some homeowners and turf managers opt for a full renovation instead: kill everything with glyphosate, wait for any bermuda grass regrowth, kill again, and then establish new zoysia from sod or plugs. This approach is faster in terms of calendar time to a clean lawn, but it is more expensive and more disruptive, and it still requires vigilance along edges where bermuda grass can re-invade from neighboring properties or sidewalk cracks.

The suppression approach described in this article works best when zoysia is still the dominant grass and bermuda grass is the intruder occupying maybe 10 to 40 percent of the stand. In that scenario, the fluazifop-triclopyr program can shift the balance decisively within two growing seasons, and the zoysia fills in the bare spots on its own.

Preventing Bermuda Grass From Coming Back

Once you have beaten back the bermuda grass, keeping it out requires ongoing attention. Bermuda grass spreads through stolons, rhizomes, and seed, and it is one of the most common grasses in warm-season climates. A neighbor’s yard, an adjacent unmowed strip, or even contaminated topsoil or compost can reintroduce it.

Keep your zoysia thick and healthy so it can resist invasion. Mow at the right height for your cultivar, fertilize enough to keep the turf dense but not so aggressively that you create conditions bermuda grass exploits, and scout your lawn edges regularly. If you spot bermuda grass creeping back in from a border, treating a small patch with fluazifop plus triclopyr in early spring is far easier than reclaiming a heavily contaminated lawn later.

Pre-emergent herbicides are sometimes suggested for preventing bermuda grass establishment from seed, but their effectiveness against bermuda grass stolons and rhizomes is limited since they target germinating seeds rather than vegetative spread. Most bermuda grass invasion in an established zoysia lawn happens vegetatively, so pre-emergents are a supporting player at best.

Weather and Year-to-Year Variability

One of the underappreciated challenges in this project is that results can vary substantially from year to year based on weather. Research on zoysiagrass response to spring herbicide applications found that warmer conditions following treatment led to faster green-up but also increased herbicidal injury, while cooler springs slowed both recovery and damage.¹⁰ Similarly, the bermuda grass suppression trials showed suppression ranging from 4 percent to 57 percent for the same midsummer timings across two different years.⁶

What this means practically is that you should not judge the program’s success or failure off a single season. A cool, wet spring might make your first-year results look disappointing, while the following year’s warmer conditions could produce a dramatic shift. Stick to the timing principles, apply the tank mix consistently, and evaluate over two full growing seasons before deciding whether the approach is working for your lawn.