Bahia grass (Paspalum notatum) is an aggressive, perennial warm-season grass that often invades and dominates desirable turf areas. Its deep, fibrous root system and tough runners allow it to survive drought and poor soil conditions, making it difficult to eliminate. It is also a prolific seed producer, sending up tough, woody stalks that are often missed by regular mowing and contribute significantly to its spread. Effective removal requires correct identification and a strategic application of selective herbicides designed to target this specific grass without harming the surrounding lawn.
Identifying Bahia Grass
Proper identification is the first step in successful removal, as the wrong treatment can damage healthy turf. Bahia grass is characterized by its coarse texture and light green color, which contrasts sharply with the finer, darker green of many lawn grasses. The leaves are typically flat or folded, tough to the touch, and sometimes display a slight V-shape when viewed in cross-section.
The most distinctive feature is the seed head, which is usually Y-shaped, resembling a tuning fork attached to a slender stem. These tall, rigid stalks appear throughout the growing season and are often resistant to normal mowing heights. The weed also spreads horizontally through stout, scaly rhizomes (underground stems) and stolons (above-ground runners), which anchor the plant firmly in the soil.
Selective Herbicides for Removal
Controlling Bahia grass in desirable warm-season turf, such as Zoysia or St. Augustine, requires selective post-emergent herbicides. These products must target the weedy grass while leaving the surrounding turf relatively unharmed. The most effective active ingredient for selective control of Bahia grass is metsulfuron-methyl, which is tolerated by Bermudagrass, Centipedegrass, St. Augustinegrass, and Zoysiagrass.
Metsulfuron-methyl is a systemic herbicide, meaning the chemical is absorbed through the leaves and translocated throughout the entire plant, including the deep root system. It works by blocking cell division, which gradually halts the growth of the Bahia grass. Because Bahia grass is tenacious, a single application is rarely sufficient for eradication, and multiple treatments are required.
Three-way herbicides containing 2,4-D, dicamba, and MCPP are commonly used in turf and can offer some suppression and broadleaf weed control, but they are not primary killers of mature Bahia grass. For a direct kill on this perennial grass, metsulfuron-methyl is necessary. Products containing quinclorac, while effective on other grassy weeds like crabgrass, are not recommended for use on Bahia grass.
Optimal Application Techniques
The effectiveness of any herbicide application depends heavily on the timing and method of delivery. Herbicides should be applied when the Bahia grass is small and actively growing, typically in the late spring or early summer. Temperatures should be moderate, ideally between 60°F and 85°F. Applying during periods of extreme heat or drought will stress the turf and the weed, reducing the herbicide’s effectiveness and potentially damaging the desirable grass.
For optimal absorption, avoid mowing the lawn for at least two days before and two days after the application. This ensures maximum leaf surface area is available to absorb the chemical. Because the leaves of Bahia grass have a waxy cuticle, mixing a non-ionic surfactant with the herbicide solution is crucial; this additive helps the chemical penetrate the leaf surface for better translocation and kill.
A follow-up application is necessary four to six weeks after the initial treatment to manage surviving plants and new sprouts from the deep root system or germinating seeds. Spot treating specific areas is often more practical than a broadcast application, especially if the infestation is localized. After application, do not water the treated area for at least 24 hours to allow the herbicide sufficient time to be absorbed by the plant tissue.
Cultural Practices for Prevention
Chemical control provides the immediate solution, but long-term prevention relies on improving the overall health of the desired turfgrass. Bahia grass thrives where other grasses struggle, so maintaining a dense, healthy lawn is the best defense. This begins with proper mowing practices, which should be set at the maximum recommended height for the desirable turf species, typically between three and four inches for many warm-season lawns.
Taller turf blades shade the soil, which inhibits the germination of Bahia grass seeds and prevents the establishment of new plants. Regular mowing, coupled with bagging clippings, prevents the prolific Y-shaped seed heads from maturing and spreading new seeds across the lawn. Proper watering involves deep, infrequent irrigation to encourage the desirable turf to develop deep roots, making it more competitive and less susceptible to the drought conditions that favor Bahia grass.
A consistent fertilization program provides the nutrients necessary for the desired grass to form a thick, competitive canopy that naturally chokes out the invasive weed. Attempting to manually remove Bahia grass is often futile due to its extensive, deep rhizome system; if the entire root is not removed, the plant will regenerate. By creating an environment where the desired grass thrives, the lawn effectively outcompetes the aggressive perennial weed.