Bermuda grass, scientifically known as Cynodon dactylon, is a perennial plant that forms sod and exhibits a high degree of variation. It spreads through stolons, rhizomes, and seeds. The stolons of Bermuda grass readily take root at specific points called nodes. At these nodes, lateral buds develop, giving rise to erect or ascending stems that can range from 5 to 40 cm in height (occasionally reaching up to 90 cm). In most species of Cynodon, the leaves grow on stems with long internodes, interspersed with one or more very short internodes. This characteristic creates the appearance of nodes with multiple leaves.
The leaf sheaths of Bermuda grass are compressed and can be round, loose, split, smooth, sparsely hairy, and up to 15 cm long. They also have a cluster of hairs measuring 2 to 5 mm in length. Auricles, which are small appendages found at the base of leaves in some plants, are not present in Bermuda grass. The collar, located where the leaf blade meets the sheath, is continuous, narrow, and has a smooth upper surface while the margins may be hairy. The leaf blades themselves measure between 2 and 16 cm in length and 1.5 to 5 mm in width. They can be smooth or have sparse hairiness, and they are folded or loosely rolled in the bud, terminating in a sharp point.
The inflorescence of Bermuda grass consists of 3 to 7 spikes arranged in a single whorl, forming a finger-like structure that is 3 to 10 cm long. The spikelets, small flower clusters, are approximately 2 to 3 mm in length and are tightly pressed against one side of the central axis (rachis). The glumes, protective structures surrounding the spikelets, are about half the length of the spikelet. The lemma, a specific part of the spikelet, is boot-shaped, pointed, and has a fringe of hairs along the central ridge (keel). It is longer than the glume. The seeds of Bermuda grass are oval-shaped, measuring 1.5 mm in length, and can range in color from straw to red. They are free within the lemma and palea, which are two structures that enclose the seed.
Rephrased: Bermuda grass possesses a durable, fibrous root system that is perennial in nature and includes robust, deeply-rooted rhizomes. The roots emerge from the nodes following the growth of new leaves or tillers during the growing season, as well as the emergence of new shoots in the spring. The color of mature roots ranges from yellow to brown, while newly formed roots appear white. Throughout the growing season, mature roots undergo deterioration, while continuous production of new roots takes place. Root production and decay are particularly prominent during the spring season, coinciding with the emergence of new shoots.
Geographical distribution of Bermuda grass.
Although it is believed to have originated in Africa, Bermuda grass now thrives across the globe, encompassing tropical and subtropical regions in Asia, North America, Central America, South America, the Caribbean, and various islands in the Pacific Ocean. It has also managed to establish a presence in temperate areas of Europe and North America; however, its expansion is limited due to its vulnerability to prolonged frost. Bermuda grass successfully invades diverse types of cultivated crops and altered ecosystems, including urban areas and transportation routes such as roads and railroad tracks, in numerous regions.
Ecological requirement of Bermuda grass
Rephrased: Cynodon dactylon, a warm-season grass, exhibits slow growth during cold weather, in shaded areas, or in dry soils. It is capable of growing in a wide range of soil types, including sandy, heavy clay, and nutrient-poor soils. However, it thrives best in medium to heavy, well-drained soil with adequate moisture. Cynodon dactylon is adaptable to both acidic and alkaline conditions and demonstrates resilience in the face of floods and droughts by regrowing from underground rhizomes. It is commonly found in tropical regions with an annual rainfall ranging from 600 to 1800 mm.
In arid regions, Cynodon dactylon can be found flourishing alongside rivers and in irrigated areas. It is prevalent in lower altitudes throughout warm regions worldwide and is known to grow along roadsides and in exposed rocky or sandy areas, even at altitudes of up to 2270 meters. It has a widespread distribution and is commonly observed in Fiji, particularly near roadsides, riversides, and hillsides, up to an altitude of 850 meters. Sometimes, it forms dense mats in the upper sections of beaches and near mangrove swamps. In New Guinea, it is a common grass found along roadsides, lawns, and plantations, and can be seen at altitudes of at least 1800 meters.
Harmful effects of Bermuda grass
- Competition with crops: Bermuda grass competes with crops for essential resources such as nutrients, water, soil, light, and space, which can result in decreased crop production.
- Allopathic effects on peach: Bermuda grass has been observed to have detrimental effects on peach trees through allelopathy, which refers to the release of chemicals that inhibit the growth or development of neighboring plants.
- Role as a host for pests and diseases: Bermuda grass acts as a host for a wide range of organisms and is often considered an important alternative host for crop pests and diseases. Examples include bacterial leaf blight of rice and covered smut of sorghum.
- Allergic reactions: The pollen of Bermuda grass has been found to trigger allergy symptoms, particularly in individuals with asthma.
- Reduction of native biodiversity: The presence and growth of Bermuda grass can negatively impact native biodiversity by outcompeting and displacing native plant species.
- Increased production costs: Managing Bermuda grass can be costly, both in terms of financial investment and labor. Controlling its growth often requires intensive efforts involving mechanical and chemical control methods, which can add to the overall production expenses.
Adaptations of Bermuda grass.
- Seed production under stress: Bermuda grass produces seed heads when subjected to stressful conditions, such as drought.
- Abundant seed production: Bermuda grass produces a large number of small seeds, with approximately 200,000 seeds per pound.
- Wide soil adaptability: Bermuda grass is capable of growing in various soil types, ranging from heavy clays to deep sands, as long as fertility is not a limiting factor.
- Tolerance to soil conditions: Bermuda grass exhibits tolerance to both acidic and alkaline soil conditions and shows high resilience in saline environments.
- Dormancy and growth: The leaves and stems of Bermuda grass remain dormant until the average daily temperature consistently rises above 50 degrees Fahrenheit for several days. However, the roots and rhizomes continue to grow for several weeks even after above-ground growth ceases.
- Semi-dormant state during dry conditions: In extremely dry conditions, Bermuda grass enters a semi-dormant state, but it possesses the ability to withstand prolonged periods of drought.
- Resilience of rhizomes: The rhizomes of Bermuda grass can lose 50% or more of their weight and still recover when favorable moisture conditions are restored.
- Deep root and rhizome penetration: Bermuda grass has the ability to develop deep roots and rhizomes, enabling it to better withstand extended periods of drought.
Cynodon dactylon, when found in disturbed areas, is a competitive and invasive weed. The most effective management approach is to promptly remove all parts of the plant upon initial detection. The spread of Bermuda grass can be restricted by the presence of taller plants. For native fields with sporadic weed distribution, targeted herbicide application and manual tilling might be sufficient for control.
However, in heavily infested sites, a more rigorous control plan is necessary. The specific control methods employed should be based on the site’s location, humidity, temperature, soil type, and precipitation.
Various methods, such as burning, herbicide application, clipping, and shading, have proven effective in controlling Bermuda grass under different conditions. To prevent resprouting and the establishment of remaining Bermuda grass rhizomes, it is crucial to promptly introduce native plants and shading materials after eradicating the weed.
The choice of management strategies depends on the extent of the Bermuda grass infestation and the height of the existing native vegetation.
Glyphosate, a commonly used herbicide, is widely employed for eliminating Bermuda grass. However, it is important to note that for optimal results, the herbicide should be applied by spraying it directly onto the leaves of the grass. The leaves are the most efficient part of the plant for absorbing the herbicide, rather than the roots.
Timing of herbicide application is another crucial factor to consider. During the dormant state of Bermuda grass, such as in January, the absorption of herbicides is reduced. At this time, the grass primarily draws nutrients from the roots, making it unlikely for chemicals applied to the leaves to reach the root system effectively. Thus, the dormant period is not suitable for killing Bermuda grass using herbicides. Herbicides should be applied from spring to fall when the leaves are fully developed and green.
Before applying herbicides, it is advisable not to clip or mow the lawn. Instead, water the lawn thoroughly one to two weeks prior to herbicide application. This ensures that the leaves of Bermuda grass are green and spread out, enabling them to effectively absorb the chemical.
Glyphosate is a systemic herbicide with a wide range of effectiveness. However, it should be noted that glyphosate is not effective when Bermuda grass is in its dormant state. One of the advantages of glyphosate is its ability to target the deepest roots of Bermuda grass. After applying the herbicide, noticeable color changes, such as graying and browning, can be observed within 7-10 days. To ensure effective control, it is recommended to repeat the herbicide application and regularly water the lawn every ten days or so until new sprouts of Bermuda grass cease to reappear. It is important to apply the herbicide to the entire grass area for comprehensive control.
For effective control of Bermuda grass, the product “Clampdown 480SL 200ml/20l” can be utilized. It is crucial to use clean water to maximize the effectiveness of the chemical when preparing the herbicide solution.