Bermuda grass, scientifically known as Cynodon dactylon, is a prized warm-season turf known for its durability and dense, vibrant growth. This aggressive nature means it competes fiercely with weeds, which can quickly invade and compromise the lawn’s uniform appearance. Successfully managing weeds requires choosing the right chemistry to eliminate unwanted plants without causing damage to the desirable turf.
Why Selective Herbicides Are Necessary
Weed killers are categorized by their mechanism of action, which determines their safety profile for established lawns. Non-selective herbicides, such as those containing Glyphosate, kill nearly all plant material they contact. Applying a non-selective product across a Bermuda lawn would result in widespread turf death, making it suitable only for spot treatments or for clearing an area completely before replanting.
Selective herbicides are designed to target specific plant groups based on biological differences, allowing the Bermuda grass to remain unharmed. These formulations exploit differences between broadleaf weeds and the Bermuda grass, which is a monocot. The active ingredients either fail to be absorbed by the grass or the grass can metabolize the chemical into an inactive form, a process the target weed cannot perform. This precise action makes selective herbicides the primary tool for maintaining a weed-free Bermuda lawn.
Specific Active Ingredients for Common Weeds
The most effective weed control strategy involves matching the herbicide’s active ingredient to the specific type of weed present. For broadleaf weeds like clover, dandelion, and spurge, combination products are recommended for comprehensive control. These typically contain a blend of auxin-mimicking chemicals such as 2,4-D, Dicamba, and MCPP (Mecoprop), which overload the weed’s growth hormones, causing lethal growth. Since Bermuda grass is tolerant of these herbicides, these “three-way” mixtures are a standard treatment.
Grassy weeds, such as crabgrass and foxtail, require a different chemical approach because they share the same biological classification as the Bermuda turf. Post-emergent control of young crabgrass is effective with products containing Quinclorac, which works by disrupting cell wall synthesis in susceptible grasses. Quinclorac is generally safe when used according to label instructions, though it can occasionally cause temporary yellowing of Bermuda grass.
For stubborn, grass-like weeds, specifically nutsedge, specialized active ingredients are required, as standard weed killers are often ineffective. Nutsedge control relies on herbicides such as Halosulfuron or Sulfentrazone, which are translocated throughout the plant, including the underground tubers, to prevent re-sprouting. These products provide targeted control against both yellow and purple nutsedge species without damaging the established Bermuda grass.
Essential Application Timing and Techniques
The success of any weed killer depends on the precise timing and method of application. A proactive pre-emergent strategy is the first line of defense, utilizing herbicides like Prodiamine to create a chemical barrier in the soil that inhibits the cell division of germinating weed seeds. This application must occur before the target weed seeds sprout, typically in the spring before the soil temperature consistently reaches 55 degrees Fahrenheit.
Post-emergent products target weeds that are already visibly growing and require careful attention to temperature to maximize efficacy and protect the turf. Applying these herbicides when the air temperature is between 65 and 85 degrees Fahrenheit is ideal, as weeds are actively growing and most susceptible to absorption. Applying post-emergent treatments when temperatures exceed 90 degrees Fahrenheit can cause significant injury to the Bermuda grass, as the turf becomes stressed.
Proper technique often includes the use of surfactants, or “stickers,” to help the herbicide solution adhere to the waxy leaf surfaces of the weeds. Many post-emergent products must be applied to dry foliage and require a rain-free period of at least 24 to 48 hours to ensure the chemical is fully absorbed. Granular pre-emergent products must be watered into the soil soon after application to activate the chemical barrier, while liquid post-emergent sprays typically need to dry on the weed surface.