ST. LAWRENCE EASTERN LAKE ONTARIO PARTNERSHIP FOR REGIONAL INVASIVE SPECIES MANAGEMENT
Invasive watermilfoil (Myriophyllum spicatum L. ), commonly called Eurasian watermilfoil, is a submerged aquatic plant native to Eurasia and Northern Africa.
M. spicatum has the ability to overwinter and grow rapidly in the spring, blocking out sunlight needed by native plants. It impairs the ability of some fish to spawn and reduces the health of aquatic habitats.
M. spicatum is a tier-4 species and is considered to be too widespread in our region to eradicate. However, high priority resources, like rare species or recreation assets, are protected through localized management strategies.
M. spicatum can grow in depths up to 33 feet; growing best in fertile, fine texture, inorganic sediments. It prefers highly disturbed lake beds, heavily used lakes and lakes receiving nitrogen and phosphorus-laden runoff. Also found in ponds, slow-moving streams, reservoirs, and estuaries. It is not as successful in undisturbed areas where native plants are well established.
Leaves are submerged, feathery, with a blunt tip, and go limp when taken out of the water. There are four to five leaves that whorl around the stem, each leaf has 12-21 thread-like pairs of leaflets.
Stems are long, slender, branching, hairless, and become leafless toward the base. They can grow up to 20 feet in length. Stems are generally limp when out of the water and often appear reddish, particularly near the plant tips.
Flowers are small red, pink, or yellow, 4-parted flowers on a spike that projects 2-4 inches above the water surface
Seeds are globoid-ovoid in shape measuring 2 mm. Long with 4 lateral lobes; these lobes are smooth, except along their margins, where they may be slightly warty. Each fruit is divided into 4 chunky 3-sided seeds.
Identifying aquatic milfoil species can be tricky because they look very similar at first glance. However, looking closely at the leaflet pairs, leaf texture out of water, and growth shapes help with identification.
Eurasian watermilfoil spreads primarily by fragmentation due to boating and wave action. Fragments stay alive for weeks if kept moist. They also reproduce by runners. Therefore, it is important to Clean, Drain, and Dry all watercraft before entering and leaving a body of water.
A mixture of physical removal for small patches, systemic aquatic herbicides for larger infestations, and bottom barriers to block sunlight is the best approach for controlling Eurasian watermilfoil. Always check local regulations and permit requirements before treatment.
Physical Control:
Hand-pulling is the best method for small infestations. Raking is also an option. All plant fragments must be removed from the water and shoreline to prevent spreading the infestation.
Bottom Barriers: Sheets of materials can be attached to a lake bottom to prevent plant growth by blocking sunlight; this approach is best used locally around docks.
Diver-Assisted Suction Harvesting (DASH): A manual removal method where divers pull the plant out at the roots using a suction intake tube. This technique can be labor intensive and costly but is highly effective at capturing the entire plant and keeping fragments from breaking off and spreading to new areas.
Chemical Control:
2,4-D and Fluridone are the most commonly used chemicals to control this species. However, both of these have mixed results and can affect native plant populations. Permits are required for chemical applications in aquatic and sensitive habitats; always follow chemical instructions.
Biological control:
Researchers have found a native North American weevil that feeds on Eurasian water-milfoil, but this method also has mixed results. Contact local DEC for more information.
PREVENTION
Prevent the introduction of invasive species into the SLELO PRISM.
EARLY DETECTION & RAPID RESPONSE
Rapidly detect new and recent invaders and eliminate all individuals within a specific area.
COOPERATION
Share resources, including funding personnel, equipment, information, and expertise.
INFORMATION MANAGEMENT
Collect, utilize, and share information regarding surveys, infestations, control methods, monitoring, and research.
CONTROL
Control invasive species infestations by using best management practices, methods and techniques to include: ERADICATION (which is to eliminate all individuals and the seed bank from an area), CONTAINMENT (which is reducing the spread of established infestations from entering an uninfested area) and SUPPRESSION which is to reduce the density but not necessarily the total infested area.
RESTORATION
Develop and implement effective restoration methods for areas that have been degraded by invasive species and where suppression or control has taken place.
EDUCATION & OUTREACH
Increase public awareness and understanding of invasive species.
INNOVATION
Develop and implement innovative technologies that help us to better understand, visualize, alleviate or manage invasive species and their impacts or that serve to strengthen ecosystem function and/or processes.
Rob Williams
PRISM Coordinator
Megan Pistolese
Outreach and Education
Brittney Rogers
Aquatic Invasive Species
Robert Smith
Terrestrial Invasive Species