Bermuda grass (Cynodon dactylon) is a warm-season perennial grass known for its aggressive growth habit. Its ability to thrive in harsh conditions makes it a desirable turf choice for some, but an extremely challenging weed for others. Achieving long-term eradication requires understanding the plant’s biology and employing methodical strategies designed to destroy its deep-seated survival mechanisms. This article outlines the comprehensive strategies needed to eliminate Bermuda grass permanently from a landscape.
The Biological Resilience of Bermuda Grass
The difficulty in eliminating Cynodon dactylon stems from its dual system of horizontal stems that allow it to spread and store energy simultaneously. The plant uses above-ground runners, called stolons, to rapidly colonize new areas, with each node capable of rooting and forming a new plant. This surface growth allows for quick visual recovery after mowing or light weeding, masking the true problem below ground.
The plant’s true survival mechanism lies in its extensive network of underground stems, known as rhizomes. These rhizomes store large reserves of carbohydrates, allowing the grass to survive drought, cold, and physical injury. For eradication to be permanent, the entire rhizome network must be destroyed, as removing only the visible shoots allows the plant to rapidly regrow.
Systemic Chemical Strategies for Permanent Removal
The most established method for permanent eradication involves the use of systemic, non-selective herbicides, which are absorbed by the leaves and transported throughout the entire plant system. The active ingredient most commonly used is a chemical that inhibits the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), effectively blocking the production of aromatic amino acids necessary for plant growth. This systemic action allows the herbicide to reach and eliminate the deep rhizomes that fuel regrowth.
Optimal timing is a significant factor in maximizing the effectiveness of this chemical application. Apply the herbicide when the grass is actively growing and has maximum leaf surface area, typically during the peak warmth of late summer or early fall. During this period, the plant naturally moves sugars and energy reserves downward into the rhizomes for winter storage, pulling the systemic herbicide along. Avoid mowing the grass for one to two weeks before treatment to ensure maximum leaf area for absorption.
A single treatment is rarely sufficient for permanent control because of the massive energy reserves held in the rhizomes. A sequence of repeated applications is necessary, often requiring two to four cycles to deplete the reserves and eliminate any emerging growth. After the initial application, wait at least seven days before any soil disturbance or mowing to allow the chemical to fully translocate.
For subsequent applications, water the area to encourage surviving rhizomes to sprout new growth. This fresh, actively growing foliage then becomes the target for the next round of herbicide, ensuring the entire network is eventually exposed and destroyed. Following the final treatment, waiting two to three weeks is advisable before physically removing the dead material or preparing the area for replanting.
Non-Toxic Methods for Complete Eradication
For those seeking alternatives to chemical treatments, non-toxic methods offer a path to complete eradication, though they often require more time and labor.
Soil Solarization
One effective non-chemical strategy is soil solarization, which uses the sun’s heat to kill the rhizomes. This involves mowing the grass low, watering the area thoroughly, and covering the soil with clear, UV-resistant plastic sheeting. The edges of the plastic must be buried to trap heat, raising the topsoil temperature high enough to kill rhizomes and existing seeds. The plastic must remain in place for a minimum of four to eight weeks during the hottest part of the summer. Solarization also has the added benefit of eliminating weed seeds and certain soil-borne pathogens.
Smothering
Another physical method is smothering, achieved through sheet mulching, which starves the grass of light and oxygen. Lay down a thick, overlapping layer of light-blocking material, such as cardboard or black plastic, over the entire infested area. A deep layer of organic mulch, approximately four to six inches, is then placed on top to hold the barrier down. This barrier must remain in place for several months to fully exhaust the rhizomes’ energy reserves.
Mechanical Removal
Mechanical removal, such as digging, requires meticulous care to ensure permanence. Standard tilling is often counterproductive, as it chops rhizomes into small fragments, each capable of sprouting a new plant. Careful hand-digging with a garden fork is recommended to loosen and lift the rhizomes intact. Every piece of the underground stem must be removed from the site, as any left behind will lead to re-establishment.
Post-Removal Soil Management and Prevention
Achieving a permanent kill is only the first step; long-term prevention focuses on creating an environment where Bermuda grass cannot successfully re-establish. After eradication, monitor the prepared soil vigilantly for any new shoots. New sprouts indicate a missed rhizome fragment or a germinating seed, and these must be removed immediately before they can build new energy reserves.
Establishing a dense, competitive planting is one of the best forms of prevention against re-establishment. Planting a desirable ground cover or a dense turf species will shade the soil, depriving any new Bermuda grass seedlings of the intense sunlight they require. Taller cover crops can be used temporarily to exhaust the unwanted grass by blocking its full sun requirements. Preparing the soil with amendments before replanting ensures new plants have the best start to out-compete future invaders. Proper cultural practices, such as maintaining a dense, healthy lawn, will make it difficult for wind-blown seeds or missed rhizome pieces to successfully colonize the area.