Bahia grass (Paspalum notatum) is a warm-season perennial grass that often becomes a tenacious weed in manicured lawns across the southern United States. Originally introduced for forage and erosion control, its aggressive characteristics make it a nuisance in turfgrass areas. It is difficult to eliminate because it possesses a deep, robust root system with stout rhizomes. These rhizomes allow it to spread horizontally and survive drought conditions. This combination of underground runners and a prolific seed-producing habit requires a comprehensive, multi-faceted removal strategy.
Identifying the Target and Manual Removal Techniques
Correctly identifying Bahia grass is the first step in successful removal, as its coarse texture and light-green color often distinguish it from desirable turf species. The most recognizable feature is its distinctive seed head, which usually consists of two spikes attached at the tip of the stem, forming a “Y” or “V” shape above the lawn canopy. These seed heads contain dark-brown to black seeds, which are easily dispersed by mowing, foot traffic, or wind, further spreading the infestation.
For smaller, localized patches, manual removal is a viable, chemical-free option, but it requires diligent effort. Due to the plant’s extensive root system and rhizomes, the entire clump, including all underground structures, must be completely dug out to prevent re-sprouting. Hand-pulling the grass when the soil is moist will make the task easier. However, even a small piece of rhizome left behind can generate a new plant.
A non-chemical method for small, contained areas is soil solarization or smothering. This involves mowing the grass very low, watering the area, and then covering it with clear plastic sheeting or multiple layers of wet newspaper weighed down with mulch. This technique uses heat or light deprivation to kill all vegetation, including the roots and existing seed bank. It typically requires six to eight weeks during the warmest part of the year. While effective, this process is often impractical for a large lawn because it temporarily eliminates all grass in the treated section.
Strategic Chemical Control for Turfgrass
Because of the aggressive spread and deep root system of Bahia grass, chemical control is often necessary to manage widespread infestations. When controlling weeds in a turf area, a selective herbicide must be chosen. Non-selective options like glyphosate will kill the desirable lawn grass along with the Bahia grass. Selective herbicides are formulated to target the weed while minimizing damage to the surrounding turfgrass species.
The most effective selective post-emergent active ingredients include metsulfuron-methyl and certain sulfentrazone mixtures. Metsulfuron-methyl has shown high efficacy against the Pensacola variety of Bahia grass, a common lawn invader. Imazaquin and atrazine are also used, though atrazine is only safe for use on St. Augustine and centipedegrass lawns.
The timing of the application is important for a successful outcome. Treatment must begin in late spring or early summer when the Bahia grass is actively growing and the plants are relatively small. Because this perennial grass spreads via rhizomes, a single application is rarely enough to achieve full control. Sequential applications are typically required, spaced four to six weeks apart, to eliminate plants that sprout from rhizomes or germinate from the seed bank. Always read the herbicide label to confirm safety for your specific turf type, observe temperature restrictions, and consider adding a non-ionic surfactant to the tank mix to increase effectiveness.
Lawn Restoration and Preventing Reinfestation
Once the chemical treatment has killed the Bahia grass, the resulting bare patches must be addressed to prevent other weeds from colonizing the soil. The dead grass should be raked out, and the soil prepared for re-establishment by tilling the top few inches and adding topsoil if necessary. The bare areas can then be repaired by laying down sod, inserting plugs of the desired turfgrass, or by reseeding with a high-quality seed mix appropriate for your region.
To suppress the germination of new Bahia grass seedlings from the residual seed bank, a pre-emergent herbicide application is recommended. Pre-emergents containing active ingredients like Prodiamine or Oxadiazon create a chemical barrier in the soil that inhibits seed germination for several months. This proactive measure should be applied before soil temperatures reach a level that triggers the warm-season grass seeds to sprout.
Long-term prevention relies on good cultural practices that favor the desired turfgrass species. Mowing the lawn at the highest recommended height for your turf, typically three inches or more, encourages a dense canopy that shades the soil and suppresses the germination of new weed seeds. Watering deeply and infrequently trains your desirable grass to develop a robust root system. This helps it outcompete the shallow-rooted seedlings of Bahia grass for water and nutrients.