Bermuda grass (Cynodon dactylon) is a warm-season perennial grass known for its robust and aggressive growth. It spreads rapidly using above-ground runners (stolons) and extensive underground stems (rhizomes). This deep, persistent root structure makes it one of the most difficult weeds to control in lawns and gardens, often requiring chemical intervention. Glyphosate, a widely used non-selective herbicide, is frequently considered the most effective chemical option for eradication. While glyphosate can kill Bermuda grass, success is not guaranteed by a single application, demanding a specialized, multi-step approach.
Understanding Glyphosate Action
Glyphosate is a systemic, non-selective herbicide that moves throughout the entire plant after application, affecting virtually all vegetation it contacts. Its mode of action involves disrupting the shikimate pathway, a metabolic process found only in plants and certain microorganisms. Specifically, glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSP synthase).
Inhibition of EPSP synthase prevents the plant from synthesizing the three essential aromatic amino acids: phenylalanine, tyrosine, and tryptophan. These amino acids are fundamental for protein synthesis and growth processes. Their depletion effectively starves the plant from within, leading to death. Since animals lack the shikimate pathway, glyphosate targets plant biology specifically.
The systemic nature of the herbicide is crucial for managing deep-rooted weeds like Bermuda grass. Once absorbed through the leaves, glyphosate is translocated through the plant’s vascular system down to the rhizomes and stolons. This internal movement poisons the energy storage structures, preventing the plant from resprouting after the foliage dies. Therefore, glyphosate is only effective on actively growing plants, as translocation relies on the plant moving nutrients to the roots.
Specific Treatment Protocols for Bermuda Grass
Effective eradication requires precise timing and repeated applications due to the plant’s extensive rhizome network. The chemical must be applied when the grass is healthy and actively growing, typically from late spring through early fall. Applying the herbicide during drought or dormancy severely limits uptake and translocation, leading to poor results.
The best time for application is often late summer or early fall. During this period, perennial grasses naturally move carbohydrates downward for winter storage, which facilitates maximum translocation of the herbicide to the rhizomes. Preparation is necessary: refrain from mowing for 7 to 14 days before application to ensure ample leaf surface area for absorption.
A single treatment is rarely sufficient to exhaust the root reserves, so a sequential application schedule is required. Protocols recommend two to four applications spaced 10 to 21 days apart. This spacing allows the initial treatment to work while giving surviving rhizomes time to produce new foliage for the subsequent application. Wait at least seven days after each treatment before disturbing the area by mowing or cultivation to maximize translocation time.
Safety precautions are mandatory when handling non-selective herbicides. Wear personal protective equipment, such as gloves, long sleeves, and eye protection, during mixing and spraying. Applications must be performed on calm days to prevent spray drift, which can damage adjacent plants. Always follow the manufacturer’s label for mixing ratios; higher concentrations do not necessarily increase effectiveness but do increase environmental risk.
Non-Chemical Control Methods
For those who prefer to avoid chemical herbicides, several non-chemical methods can manage or eliminate Bermuda grass, though they require patience and physical effort.
Soil Solarization
Soil solarization uses heat to kill the grass and its seeds. This involves mowing the area low, watering it thoroughly, and covering it with a sheet of clear plastic (1 to 6 mil thick). This must be done during the hottest part of the summer for a minimum of four to eight weeks. The plastic traps solar radiation, raising the soil temperature high enough to destroy rhizomes and viable seeds.
Smothering (Sheet Mulching)
Smothering works by denying the grass access to sunlight. This process involves laying down a thick layer of light-blocking material, such as several layers of newspaper or cardboard, over the affected area. This barrier is then covered with several inches of organic mulch or compost. The lack of light prevents photosynthesis, eventually starving the grass, though this can take several months.
Physical Exclusion and Competition
Cultural practices focused on physical exclusion and competition are also useful. Deep edging involves installing a physical barrier at least six inches deep into the soil along garden beds to prevent the spread of stolons and rhizomes. In turf settings, maintaining a dense stand of desirable grass can suppress Bermuda grass. This is achieved by mowing the preferred turf species at a taller height (three inches or more), which reduces sunlight available to the low-growing Bermuda grass.
For small patches, manual removal remains an option, but meticulous effort is required to ensure all rhizome fragments are extracted, as any left behind can quickly resprout. Selective herbicides are also available that can target Bermuda grass while preserving certain types of desirable turf, such as fescue. However, these products often require specialized knowledge and multiple treatments.