What Are Cattails?
Cattails are tall marsh plants from the genus Typha that grow in dense stands in shallow, still waters (Britannica). They feature long, slender green leaves that can reach 10 feet tall and tan, cigar-shaped flower spikes. Cattails spread through both seed dispersal and vegetative reproduction via rhizomes, allowing them to quickly colonize wetlands and create large monocultural stands (The Nature Conservancy).
Cattails thrive in stagnant shallow waters like ponds, marshes, ditches, and the edges of lakes. They grow best in full sun and moist, rich soils. They can grow in water depths from a few inches to two feet deep (National Park Service). Their adaptability allows them to rapidly spread and dominate wetland ecosystems.
Why Get Rid of Cattails?
There are several reasons why you may want to get rid of cattails in your pond:
Cattails can overtake a pond very quickly. According to Solitude Lake Management, “Even if cattail growth is localized to a small pond’s shoreline, if dense and completely around the pond, access to the water is severely reduced for transient wildlife species.” Their rapid growth allows them to crowd out other beneficial native plants.
A dense stand of cattails can negatively impact the aesthetics of your pond. Many homeowners prefer a more diverse aquatic plant environment. The monoculture created by cattails limits biodiversity.
Cattails can also create stagnant areas in the pond leading to poorer water quality. As they die back in winter, they leave holes in the vegetation, impacting oxygen circulation.
Dangers of Cattails to Fish
Cattails themselves do not directly harm fish in ponds. However, an overgrowth of cattails can reduce oxygen levels and impact water quality, creating an indirect danger to fish populations (Source).
As cattail stalks die off and decay, they can deplete oxygen in the water. This is especially problematic in small, shallow ponds. Large masses of decaying cattail debris can lead to hypoxic or anoxic conditions, making it difficult for fish to breathe (Source).
Dense cattail growth shades the water so sunlight cannot reach submerged plants. This reduces photosynthesis and oxygen production in the pond. Fish rely on aquatic plants to continually generate oxygen and remove carbon dioxide.
Too many cattails may also alter the pond’s pH balance by releasing tannins as they decompose. Significant pH fluctuations can stress fish and make them more susceptible to disease (Source).
So while cattails themselves do not directly impact fish, managing their spread is crucial to maintain safe oxygen levels, pH, and overall water quality for healthy fish populations.
Manual Removal
One of the most common ways to get rid of cattails is by manual removal. This involves digging up the roots or cutting the plants at the base (Cornell Cooperative Extension). Manual removal can be very labour intensive and is often ineffective in the long-term if the entire root system is not fully removed.
To remove cattails manually, you’ll need to dig down and pull up as much of the root system as possible. The roots can extend over 6 feet down into the sediment, so this is not an easy process. Cutting the leaves and stems at the base can help reduce further spread, but regrowth will occur if the roots remain intact (Weeders Digest). For the best results, manual removal needs to be repeated regularly to catch any regrowth from remaining roots.
While manual removal can help in the short-term, it is very labour intensive and often not a permanent solution. The roots left behind will allow the cattails to regrow quickly. For heavily infested areas, other control methods may be more effective long-term.
Smothering
One non-chemical method for controlling cattails is to smother them by covering the plants with tarps, landscape fabric, or other barriers. This cuts off light and stops photosynthesis, eventually killing the plant. According to The Pond Guy, covering cattail growth with an opaque material for 6-8 weeks can be effective. However, multiple applications may be needed, as the plant’s extensive rhizome system allows it to resprout if not entirely smothered.
When using tarps or landscape fabric, it’s important to weigh down the edges well so it makes full contact with the soil, depriving the rhizomes of light. Overlapping the material can also help prevent any gaps. Monitoring regularly and reapplying if any sprouts emerge from under the barrier is key. While smothering avoids chemicals, it can be labor intensive. Consulting an expert may be advisable for large infestations.
Herbicides
Herbicides containing glyphosate, such as Roundup, Rodeo, and AquaNeat, can be effective at controlling cattails when used properly.[1] Glyphosate is absorbed through the leaves and moves throughout the entire plant, killing both the foliage and the roots. It does not harm the soil so it can be safely applied near water sources.[2]
While glyphosate herbicides are approved for aquatic use, care must still be taken to avoid harming fish and wildlife. Only aquatic-approved formulas should be used, not standard landscaping products. Follow all label directions carefully regarding dosage, timing, and application method. Do not allow the herbicide to come into direct contact with the water, as this can temporarily increase the concentration and pose a risk to fish.[1]
Spot treatment of individual cattail stalks is safer than broadcasting across large areas. Monitor fish behavior during and after application for any signs of distress. Having a professional service apply the herbicide can help ensure proper technique and minimize risks.[3]
With cautious use, glyphosate herbicides can provide selective and effective cattail control without impacting pond ecology.
[1] https://shop.naturalwaterscapes.com/cattail-killer-pack/
[2] https://aquaplant.tamu.edu/management-options/cattail/
[3] https://www.lakerestoration.com/product/cattail-and-waterlily-control/
Biological Controls
One biological control sometimes used for cattail management is the grass carp (Ctenopharyngodon idella), an herbivorous fish species. Research shows that grass carp eat the shoots and leaves of cattails, but do not provide effective long-term control of cattail stands. One study found that while grass carp initially reduced cattail abundance by 88%, the cattails rebounded to pretreatment levels within two years after stocking [1].
Grass carp are also non-selective feeders that may consume other desirable aquatic plants in addition to the targeted cattails. Their feeding can harm native submerged vegetation and open up areas for invasive plants to spread [2]. For these reasons, grass carp do not provide a reliable, targeted method for long-term cattail management.
Altering Environment
Draining or dredging the pond is one technique for removing cattails, as it exposes the root system. However, this may not be a feasible option, especially for larger ponds. Completely draining the pond risks harming or killing the fish and other aquatic life. Partial draining can be done in sections over time, but is still disruptive. Dredging to remove cattail roots is effective, but highly labor intensive and expensive. There’s also a risk of damaging the pond liner if not done carefully.
Even after draining or dredging, cattails are aggressive growers and will likely regrow from any remaining root fragments. So this method provides only temporary relief unless combined with other techniques like smothering or using herbicides on regrowth. According to Cornell Cooperative Extension, “If you want to control cattails, you will need to disrupt the root system through cutting, hand-pulling, dredging, flooding, freezing, or chemical herbicides.” [1]
Overall, altering the pond environment by draining or dredging can help reduce cattails, but is often impractical and needs to be combined with additional maintenance. It does not provide a permanent solution on its own.
Ongoing Maintenance
Controlling cattails requires an ongoing commitment to maintenance. A single removal effort, whether manual, chemical, or biological, will likely not provide permanent results. Cattails spread aggressively via rhizomes, so any remaining root fragments can resprout. According to Cornell Cooperative Extension, “To provide long-term control,Management efforts may need to be repeated for several years until the seed bank and rhizomes are exhausted.”
The most effective long-term strategy is to use a combination of control methods. For example, you could start by manually removing as many plants and roots as possible. Then apply an aquatic herbicide like Imazapyr to remaining roots and shoots. Follow up periodically with spot treatments of any regrowth. Using multiple integrated methods provides the best chance of long-term control.
It’s also critical to take early action at the first sign of cattail growth. Small patches are much easier to control than established stands. The longer you wait, the more labor and herbicide will be required. Cornell Cooperative Extension notes, “It is much easier to prevent establishment of cattail stands than to try and control them later.” Stay vigilant and don’t let cattails gain a foothold.
When to Seek Expert Help
In some cases, it may be best to seek the help of an aquatic weed control professional. According to The Pond Guy, you may want to consider hiring a professional for severe widespread growth, if you have a highly valued fish population you want to protect, or after unsuccessful attempts at self-control.
Widespread growth can be difficult to manage on your own, and may require commercial grade herbicides or equipment that professionals have access to. If you have prized koi or other fish you want to safeguard, trusting an expert can help mitigate risks. They have experience using herbicides and techniques selectively and safely.
If you’ve tried recommended organic methods like smothering without success, a professional can assess why it failed and determine the most effective solution. They have specialized knowledge of aquatic weed control that can make eradication more successful after initial failed attempts. Their expertise using the right herbicide, timing, and method can effectively remove cattails while protecting your fish population.
