Curly Leaf Pondweed Control: Practical Strategies for Lakes and Ponds

Key Takeaways

Curly leaf pondweed (potamogeton crispus) is a cold-tolerant invasive aquatic plant that forms dense surface mats and drives mid summer algae blooms in lakes and ponds across northern New Jersey, New York, Vermont, and Ontario.

• Effective curly leaf pondweed control focuses on early spring herbicide treatments before turion production, reducing nutrients that fuel growth, and combining mechanical, biological, and chemical control where appropriate.
• Uncontrolled curlyleaf pondweed crowds out native plants, degrades water quality, and interferes with boating, swimming, and fishing.
• Eradication of curly leaf pondweed is often not possible for large infestations; long term management is typically ongoing, creating a perpetual need for monitoring and adaptive treatment.
• Ready Scout, LLC provides end-to-end services-assessment, permitting, treatment, and follow-up monitoring-for controlling curly leaf pondweed as part of integrated pond management programs.

Understanding Curly Leaf Pondweed and Why It Becomes a Problem

Curly leaf pondweed is a submerged invasive plant with crinkled leaves and wavy, finely toothed margins that give it a very distinctive appearance, often compared to lasagna noodles. Growing from rhizomes anchored in the pond bottom, this invasive aquatic plant reaches lengths up to one meter in nutrient-rich, alkaline waters-even in low light conditions.

Its life cycle sets it apart from most aquatic plants. Curly leaf pondweed begins growing in late fall and early spring, can grow under 50 cm of ice and snow, and reaches maximum growth by late spring. Turions-small greenish brown pinecones-like vegetative buds-drop into the sediment before the plant dies back by midsummer, leaving decomposing mats. Turions have a germination rate of 60–80%, and turions can remain dormant for several years in sediment, fueling new plants year after year.

Key ecological impacts include:

• Reducing biodiversity by displacing native aquatic plants-it blocks sunlight, limiting growth of native species and other plants that emerge later in the season
• Dense surface mats that restrict fish habitat and foul boat propellers, making recreational activities difficult
• Decomposing curly leaf pondweed can deplete oxygen levels in the water column, triggering algal blooms and potential fish kills

This competitive edge over most plants comes from its ability to photosynthesize in cold water temperatures while other species remain dormant. The plant thrives across Ready Scout's service region, where lake communities regularly experience these impacts.



Mechanical and Physical Control Options

Mechanical and physical methods remove or suppress biomass directly, but require careful timing and execution to avoid spreading seeds and plant fragments.

• Hand pulling and raking works well for small ponds and shoreline areas. Mechanical removal should occur before seeds appear above the water surface. Pull plants as close to the sediment as possible and ensure complete removal of plant fragments to prevent regrowth. Physical control can effectively manage small ponds, though the work is labor-intensive.
• Mechanical harvesting provides short-term relief for boating lanes and beaches. Mechanical harvesting reduces recreational issues but does not eradicate curly leaf pondweed, since turions remain dormant in the lake bottom. Repeated cuts per season are necessary, and loose fragments must be collected.
• Bottom barriers (benthic mats) placed over the pond bottom suppress growth in high-priority zones like docks and swimming areas. Gas-permeable fabrics require anchoring, seasonal maintenance, and often permitting.
• Water-level drawdown, where feasible, exposes sediment to winter freezing and desiccation, reducing viable turions and rhizomes. This approach requires case-by-case evaluation for dam safety and regulatory approval.

Mechanical removal can reduce biomass but is labor-intensive and rarely depletes the turion bank alone. Ready Scout evaluates each site to determine where mechanical removal makes sense and integrates these actions into a broader aquatic weed control and management plan.

Chemical and Biological Control of Curly Leaf Pondweed

When curly leaf pondweed dominates a water body, herbicide control is often needed. Controlling curly-leaf pondweed requires early-season herbicide applications combined with physical removal for best results.

Herbicide strategies:

• Contact herbicides like endothall and diquat are effective herbicides for curly leaf pondweed. Selective herbicides are best applied in early spring at water temperatures around 50–60°F, before turion production begins. A granular herbicide formulation can deliver product directly to target beds.
• A systemic herbicide such as fluridone acts more slowly, requires sustained concentrations, and can affect non-target species if not carefully managed. Most herbicides require professional dosing calculations and permitting.
• Chemical control includes using herbicides like diquat and endothall at low dose rates timed to suppress turion production. Research shows these early season treatments can reduce curly leaf frequency by over 90%.

Cautions: Treating large areas too late-when the plant dies back naturally-risks dissolved oxygen crashes from decaying plants and can trigger algae blooms. Post-treatment monitoring of oxygen levels is essential to protect fish.

Biological options are limited. Grass carp may consume curly leaf pondweed but can also eat native plants, reducing biodiversity if stocked at high densities. A fact sheet from Rutgers NJAES notes curly leaf is a preferred food, but permits are required and grass carp do not consume turions in the sediment, so herbicide treatments and mechanical methods remain necessary.

Ready Scout provides expert plant and algae management services including herbicide program design, permit acquisition, application at optimal timing, and follow-up plant and water quality surveys to track long-term control.

Integrated Pond Management: Addressing Algae Blooms and Long-Term Control

Controlling curly leaf pondweed alone will not fix an unhealthy lake. Successful management links invasive plant control with nutrient reduction and aquatic weed control for overabundant aquatic plants and nuisance algae.

Key nutrient sources driving algae blooms include fertilizers from lawns and golf courses, agricultural runoff, failing septic systems, and stormwater from developed shorelines. Nutrient management involves reducing phosphorus and nitrogen loading into water bodies through:

• Establishing vegetated buffer strips along shorelines
• Using phosphorus-free fertilizers
• Stabilizing eroding banks and treating stormwater before it reaches the pond

Aeration and circulation systems improve dissolved oxygen at depth, reduce internal nutrient loading from sediment, and create conditions less favorable for both curly leaf pondweed and nuisance levels of algae. Ongoing monitoring-water chemistry, Secchi depth, mapped plant surveys-guides decisions about when follow-up treatments are needed and tracks recovery of native plant communities.

Ready Scout specializes in professional lake consulting and integrated lake and pond management, combining invasive species control, aeration system design and installation, water quality monitoring, and community training so lake associations become more self-sufficient over time.

Working with Ready Scout and Additional Resources

Curly leaf pondweed control almost always benefits from professional lake consulting and management. A typical Ready Scout project begins with a site visit and plant survey, mapping curly leaf pondweed beds, sampling water quality, and discussing goals-whether for aquatic recreation, fisheries, or aesthetics. The result is a written management plan with clear timelines.

Ready Scout assists with all necessary permits for herbicide use, drawdowns, and aeration installations across northern New Jersey, upstate New York, Vermont, and southern Ontario as part of its sustainable lake management services. For additional resources, consult your state extension service publications on curlyleaf pondweed and regional invasive species councils for guidance on aquatic herbicide regulations.

Contact Ready Scout today to schedule a lake or pond assessment, request a curly leaf pondweed control plan, or set up an ongoing consulting relationship for your lake association or private water body.

Frequently Asked Questions About Controlling Curly Leaf Pondweed