Bahia grass is a warm-season perennial grass and a widespread weed in lawns across the Southern United States. It is an aggressive invader that spreads rapidly through seeds and rhizomes. Centipede grass is notoriously sensitive to many common herbicides, making the elimination of Bahia grass a precise process. Successfully removing this weed requires a targeted strategy that prioritizes the health of the Centipede turf.
The Specific Challenge: Identifying Bahia Grass and Centipede Sensitivity
Identifying the invader accurately is the first step toward effective control. Bahia grass is easily recognized by its distinctive, long, thin seed heads, which feature two to three spikes forming a Y-shape or V-shape. It grows in a coarse, open habit, often forming noticeable clumps that are lighter green than the surrounding turf. The weed also possesses deep, extensive rhizomes, which allow it to spread aggressively and make manual removal difficult.
Centipede grass is a slow-growing turf known for its low maintenance requirements and its intolerance for many chemical treatments. Standard herbicides containing ingredients like 2,4-D or MSMA can cause severe yellowing, stunting, or even death in Centipede lawns. This low tolerance means that any chemical application must be precisely chosen and applied at the correct rate to avoid damaging the desirable turf. Ignoring the grass’s sensitivity to certain compounds is a common cause of widespread lawn damage when attempting weed control.
Cultural and Manual Removal Strategies
Non-chemical methods are important for managing Bahia grass and supporting the Centipede lawn’s health. For small, isolated patches, hand-pulling is a viable option. However, the entire root system, including all rhizomes, must be removed to prevent regrowth, as simply breaking the stem above ground will not eliminate the weed.
Optimizing cultural practices shifts the competitive advantage back to the Centipede grass. Centipede lawns should be maintained at a mowing height between 1.5 and 2.5 inches. Consistent mowing is essential to remove Bahia grass seed heads before they mature and drop new seeds, which would worsen the infestation.
Promoting a thick, healthy Centipede canopy helps naturally suppress weed germination, as Bahia grass struggles in dense shade. Watering and fertilization should be managed carefully, respecting Centipede’s naturally low nitrogen requirement. Over-fertilizing with high-nitrogen products can inadvertently encourage the aggressive growth of Bahia grass.
Selecting Centipede-Safe Herbicides
Chemical control is often necessary for established or widespread Bahia grass infestations, but the selection of the active ingredient is important. Herbicides containing metsulfuron-methyl are a primary option, as they effectively control Bahia grass and many other grassy weeds while remaining safe for Centipede turf. This post-emergent herbicide is applied to actively growing weeds. The application often requires adding a non-ionic surfactant, which helps the chemical penetrate the waxy leaves of the Bahia grass, increasing effectiveness.
Another effective active ingredient is sethoxydim, a selective grass killer that suppresses Bahia grass growth without harming the Centipede. For broad-spectrum weed control, including Bahia grass and many broadleaf weeds, atrazine is an option. Atrazine also offers some pre-emergent activity to control germinating seeds and is safe for use on Centipede grass. However, it is less effective on mature Bahia grass than metsulfuron-methyl. MSMA was historically used, but it is now heavily restricted or not approved for residential lawn use and can injure Centipede grass.
Critical Application Timing and Technique
The timing of the herbicide application is as important as the chemical choice for both weed control and turf safety. Post-emergent treatments should be applied when Bahia grass is actively growing, typically from late spring through mid-summer (May to July). Applications must be avoided when air temperatures are consistently above 85 to 90°F, as this heat stress can cause significant injury to the Centipede grass.
Before application, mowing should be avoided for several days to allow maximum leaf surface area for the herbicide to absorb. Spot treatments are preferred for scattered weeds, minimizing chemical exposure to the surrounding healthy Centipede turf. When using a liquid herbicide, the sprayer must be properly calibrated to ensure the correct concentration is applied, as exceeding the label rate can severely damage the lawn. A second application of the same herbicide is often necessary three to six weeks after the initial treatment to fully eliminate the persistent weed.
Post-Treatment Recovery and Long-Term Prevention
Once the Bahia grass has died, it leaves bare spots that must be addressed quickly to prevent the germination of new weeds. These areas should be filled promptly with Centipede grass plugs or sprigs rather than seed. Seed is slower to establish and leaves the area vulnerable for longer. Light fertilization and consistent watering aid the recovery process, helping Centipede grass stolons spread into the newly cleared zones.
Long-term prevention relies on maintaining a dense, healthy Centipede turf that naturally chokes out new weed seedlings. This involves consistent adherence to the proper mowing height and a controlled fertilization schedule that respects Centipede’s low nutritional needs. Regular soil testing to maintain the correct soil pH supports a robust lawn. A thick, well-maintained Centipede canopy is the best natural defense against future Bahia grass re-infestation.