Milfoil is an attractive plant with feathery underwater foliage. It was once commonly sold as an aquarium plant. Accidentally introduced to North America from Europe, it spread westward into inland lakes and streams, primarily attributed to being carried by boats and boat trailers, with some spreading caused by water birds. In nutrient-rich lakes, it can form thick underwater stands of tangled stems and vast mats of vegetation at the water's surface. In shallow areas, the plant can interfere with water recreation. The plant's floating canopy can also crowd out important native water plants. Plants grow well in 3-20 feet of water and often have plant stems as long as 20 feet.

A key factor in the plant's success is its ability to reproduce through stem fragmentation and underground runners. A single segment of stem and leaves can take root and form a new colony. Fragments clinging to boats and trailers can spread the plant from lake to lake. The mechanical clearing of weed beds for beaches, docks, and landings creates thousands of new stem fragments that can drift with the wind and current. Removing native vegetation creates perfect habitat for invading Eurasian water milfoil

The Impact Of Milfoil on Eagle Lake

 

The introduction of milfoil can drastically alter a water body's ecology. Milfoil forms very dense mats of vegetation on the surface of the water. These mats interfere with recreational activities such as swimming, fishing, water skiing, and boating. The sheer mass of plants can cause flooding and the stagnant mats can create good habitat for mosquitoes. Milfoil mats can rob oxygen from the water by preventing the wind from mixing and oxygenating surface waters. The dense mats of vegetation can also increase the sedimentation rate by trapping sediments. Milfoil also starts spring growth sooner than native aquatic plants and can shade out these beneficial plants. When milfoil invades new territory, typically the species diversity of native aquatic plants declines. While some species of waterfowl will eat milfoil, it is not considered to be a good food source.

Milfoil reproduces extremely rapidly and can infest an entire lake within two years of introduction to the system. Although milfoil produces many seeds, we do not believe that these seeds are important for milfoil reproduction in Washington waters. However, milfoil is able to reproduce very successfully and rapidly through the formation of plant fragments. In the late summer and fall the plants become brittle and naturally break apart. These fragments will float to other areas, sink, and start new plants. Milfoil will also grow from fragments created by boaters or other disturbances during any time of year. A new plant can start from a tiny piece of a milfoil plant. This is why milfoil can so easily be transported from lake to lake on boat trailers or fishing gear. Once established in its new home, water currents may carry milfoil fragments and start new colonies within the same water body.

Talk by many community member and lake representatives has indicated that the presence of milfoil affects property values. A recent study concerning real effects on Vermont property values can be found here. Economic Impact Survey of Eurasian Watermilfoil Removal from Houghton Lake. The real effects on Property Values.

The Real Effects on Property Values
10-20-2014 APIPP- The Actual and Potential Economic Impact of Invasive Species on the Adirondack Park The Related Press Release	Ecological Economics- The effect of an aquatic invasive species (Eurasian watermilfoil) on lakefront property values. Zhang and Boyle 8-2010.	Economic Impact Survery- of Eurasian Watermilfoil Removal from Houghton Lake

Learn More About Milfoil:
A very good page from the Vermont DEC
General Information about Eurasian Water milfoil from the State of Washington
General Information about Milfoil from Lake Luzerne
A technical explanation of milfoil from Dr. Johnson @ Cornell University facts and herbivore activity

Once milfoil becomes well-established within a water body, it is difficult or impossible to remove. There are many techniques that have been employed to control it these include hand pulling, benthic bottom barriers, mechanical harvesting, diver operated suction dredging, "rotovation" biological controls, and select herbicides. Each method has its' advantages and disadvantages for a full discussion of lake management see the link to our lake management page below.

ADEQUATE WARNING AND NOTIFICATION?

Adequate public notification and signs about milfoil and other potential aquatic invasive species, is crucial to stopping the spread. Here are examples of effective and ineffective warnings concerning milfoil. Left to right: New Hampshire, New York, and Vermont.

New Hampshire	New York State	Vermont

Michael R. Martin, Certified Lake Manager, President of Cedar Eden Environmental, observed that the VT and NH signs were quite clear in asking visitors to help stop the spreading. The NY sign, however, besides being visually uncompelling, also seems to indicate that "...Eurasian milfoil can be dispersed by fragments and tiny seeds that can remain undetected by the most concerned lake user." This seems to be saying that the lake user shouldn't bother checking for the "invisible" milfoil. Eurasian milfoil is almost exclusively spread by fragments, and the fragment has to include a leaf node (stem with leaf attached), meaning it most likely will be 1/2 inch to 1 inch in size AT A MINIMUM.

NYS in 2008 posted new signs at some Adirondack lakes that indicate "You are entering an infested lake" but fails to mention what the infestation is or what one should do either before entering the lake or when leaving and taking boats and equipment elsewhere.

Acentria ephemerella is a moth in the family Pyralidae. It is native to Europe and Asia but was inadvertently introduced to North America in the 1920's. Adults can fly, however most females are flightless and stay on the water surface where they breed with flying males. The larvae (caterpillars) feed on an array of aquatic macrophytes. However they do have a high preference for and consumption rate of Eurasian water milfoil (Buckingham and Ross 1981).

In 2000, several samples of Eagle Lake milfoil were sent to Dr. Bob Johnson, Cornell University, for analysis for the presence of herbivores. Upon examination, Dr. Johnson reported that the samples contained “a significant population of both Acentria moths and weevils”. In a follow-up sampling by Dr. Johnson in early July 2001 on Eagle Lake, he reported finding only a very limited evidence of either moths or weevils.

Triploid Grass Carp- Triploid grass carp are plant-eating fish from the Amur River Basin and lowland rivers in China and Russia. Grass carp are generally not recommended for milfoil control because milfoil is not a highly preferred food. As a result, the concern is that they can enhance milfoil growth by removing competition from native plants and opening up more area for milfoil to colonize. In Washington state, grass carp can be used for milfoil eradication/control only in water bodies where the eradication of ALL submersed aquatic plants can be tolerated.

Assessing the Potential for Bio-Control of Eurasian Watermilfoil in New York State Lakes (FL-LOWPA) 02-2009

Brant Lake Milfoil Control: Internet Research on the Milfoil Weevil, David King (Personal Opinion)

Research on Herbivore's effect on milfoil: 2000 Johnson et. al "Experimental evidence for changes in submersed macrophyte species composition caused by the herbivore Acentria ephemeralla (Lepidoptera)"

Bob Johnson Herbivore Study: 2000 Johnson et. al "Eurasian Watermilfoil Biomass Associated with Insect Herbivores in New York"

Acentria Moth pictorial lifecycle Cornell Cooperative Extension

Aquatic Weevil that eats milfoil: information Cornell Cooperative Extension

Eurasian Watermilfoil- facts and herbivore activity in NY by NYS Seagrant Bob Johnson and Bern Blossey article.

Lake Management and The Milfoil Solution Lake Bonaparte- 182,000 milfoilweevils were stocked 2002-2008 for an average of 26,000 weevils per year, EnviroScience Inc.