Cattails (Typha) are robust perennial plants that thrive in shallow water and saturated soil. They are characterized by dense, cylindrical flower spikes and extensive, starchy root systems called rhizomes. These rhizomes allow the plant to spread rapidly, creating dense stands that choke out native vegetation and reduce open water areas. This growth significantly impacts water flow and reduces the biodiversity of a wetland or pond ecosystem. Effective control requires targeting both the above-ground shoots and the persistent underground rhizomes.
Physical Removal Techniques
Manual removal is practical for small, newly established patches or areas where chemical use is restricted. The most common physical method involves cutting the shoots below the water line to interrupt the plant’s oxygen supply. Cattails use internal air channels (aerenchyma) to transport oxygen from the leaves down to the submerged rhizomes.
Cutting the stems at least 4 to 6 inches beneath the water surface causes the stumps to fill with water, drowning the root system by blocking the air supply. This technique is most effective when performed in late summer or early fall when the plant’s carbohydrate reserves are lower. Removed plant material must be collected and disposed of away from the water body to prevent re-rooting or nutrient contribution as it decomposes.
For dense, established stands, intensive approaches like digging or dredging may be necessary. Dredging mechanically removes the entire rhizome mat and accumulated sediment, restoring water depth. This method is typically done when water levels are low, allowing heavy equipment to access the pond bottom. Hand-pulling is effective for young sprouts, provided the entire root and rhizome fragment is removed.
Aquatic Herbicide Application
Chemical control offers the most effective long-term solution for large, dense infestations, relying on systemic herbicides that move through the plant to kill the entire rhizome network. Use only herbicides explicitly approved for aquatic use, such as those containing glyphosate or imazapyr, to avoid harming aquatic life or contaminating the water. These chemicals are most successful when applied in mid-to-late summer, typically after the seed heads have formed.
During this period, the plant actively transfers nutrients from the leaves down to the rhizomes in preparation for winter, maximizing the translocation of the herbicide to the root system. An aquatic-approved surfactant must be mixed with the solution to help the chemical penetrate the cattail’s waxy leaf coating. Consult local and state regulations before application, as permits are often required for applying chemicals to water bodies.
After herbicide treatment, there is potential for oxygen depletion, or fish kill, caused by the rapid decomposition of dead plant material. To mitigate this risk, treat only one-third of the infestation at a time, allowing the initial section to decay for two weeks before treating the next. Removing the dead biomass after treatment further reduces the organic load and nutrient release into the water.
Environmental Control Through Water Management
Manipulating the water level can create an environment unsuitable for cattail survival, especially in systems with water control structures. One strategy involves water level drawdown, where the water is lowered in the fall and kept low through winter. This exposes the rhizomes to freezing temperatures or prolonged drying, and this desiccation process severely damages or kills the root system.
Alternatively, deep flooding can inhibit new cattail establishment. Maintaining a permanent water depth exceeding three feet year-round prevents cattails from rooting or limits the growth of new shoots, as they prefer shallow conditions of 1.5 feet or less. High water levels also stress established plants by limiting stored carbohydrates for spring growth. However, stabilizing water levels for prolonged periods can inadvertently stimulate growth by triggering the release of stored phosphorus from the sediment (internal eutrophication).
Preventing Regrowth and Long-Term Maintenance
Effective long-term maintenance relies on preventing new rhizome growth and reducing the nutrient sources that fuel expansion. Physical barriers, such as benthic mats or heavy plastic sheeting, can be laid over the sediment after initial removal. These barriers block sunlight and physically isolate the soil from the water column, preventing the emergence of remaining rhizomes or seeds.
Cattails thrive in nutrient-rich environments, so controlling nutrient input is a primary preventative measure. Reducing the use of fertilizers near the water body and managing runoff will lower the concentration of nitrogen and phosphorus that supports aggressive growth.
Frequent monitoring is necessary, as cattails can quickly re-establish from persistent seed banks or small, missed rhizome fragments. Promptly pulling any small new shoots before they develop a strong root system prevents the recurrence of a large infestation.