Variable milfoil, an exotic aquatic plant, can make boating unpleasant by fouling boat propellers.
Ever heard of milfoil?
By Andrea LaMoreaux, NH LAKES Education Director
If you haven’t heard of variable milfoil before, you are lucky—this means you probably haven’t had to interrupt a day of boating out on the lake to painstakingly unwind the long, spindly threads of this slimy, musty-smelling, seaweed-like plant wrapped tightly, and annoyingly, around your boat propeller. Unfortunately, many of you have likely had unpleasant encounters with variable milfoil (Myriophyllum heterophllum), the unwanted exotic aquatic plant (more appropriately referred to as a “weed”) that has made its home in New Hampshire and is causing problems in 63 waterbodies.
What
is milfoil?
There are six native milfoil species present in New Hampshire that do
not cause problems because they evolved naturally in this reqion--climatic
factors and natural predators keep these native species populations in check.
Unfortunately, there are two exotic species of milfoil, variable milfoil
and Eurasian milfoil, which came to New Hampshire from a different region,
leaving their natural predators behind and allowing them to grow abundantly when
they find a place they like. Of the
two exotic milfoils, variable milfoil is the more aggressive species since it
loves the Granite State’s acidic waters.
What
does variable milfoil look like?
Variable milfoil is a submerged aquatic plant with fine, densely-packed,
feather-like leaves whorled around a main stem.
Some people say it looks like a fuzzy green pipe cleaner or a tall,
skinny underwater Christmas tree. It
can grow up to an inch per day and up to approximately 15 feet in length.
In late July, it may exhibit a three-to six-inch green spike-like flower
above the waterline.
How
did variable milfoil become established in New Hampshire?
Variable milfoil has been in New Hampshire since the late 1960s.
It likely hitchhiked its way to the Lake Winnipesaukee region on a boat
or trailer from an infested lake in another state.
Variable milfoil can live out of the water for up to a week if it remains
moist, like when it’s wound around a wet carpeted bunk on a boat
trailer—once the plant hits the water, it can start growing again.
Another theory is that milfoil was introduced into a New Hampshire
waterbody through the dumping of a home aquarium since milfoil is sometimes used
as an ornamental plant in fish aquariums. And,
some think that birds are the culprit behind the spread of variable milfoil;
however, it is unlikely that birds are the cause of very many infestations.
State biologists are convinced that boaters who recreate on many lakes
during a boating season help milfoil hitchhike its way from waterbody to
waterbody since new infestations of variable milfoil (and other exotic plants)
are usually found first in shallow waters near public boat launches.
Why
is variable milfoil a problem?
Variable milfoil infestations in lakes and ponds are undesirable because they
make recreation dangerous and unpleasant. I
doubt that anyone actually enjoys having to untangle a rat’s nest of plants
around their boat propeller. And,
believe it or not, there have been reported deaths due to drowning affiliated
with this plant. To make matters
even worse, exotic plants, including variable milfoil, disrupt the ecological
balance of waterbodies, reducing shoreline property values, and are difficult
and expensive to control. Once a
waterbody is infested with an exotic aquatic plant, it is almost impossible to
get rid of it!
Once
established, how does variable milfoil infest other areas of a waterbody?
Boat propellers will chop milfoil plants into small fragments.
These fragments float on the water surface and are at the mercy of wind
and lake currents. In a short time,
roots form on these fragments. If
washed into shallow areas, these plants will eventually take hold creating a new
milfoil colony. This process will
continue until every suitable area of the waterbody is clogged with these weeds.
What
control measures are being used in New Hampshire?
Unfortunately, once entrenched, invasive plants cannot be eradicated—they can
only be controlled. Various control
practices, including hand-pulling, benthic barriers, and herbicide applications
are being used throughout the state. Such
weed management practices cost hundreds of thousands of dollars annually for the
state, municipalities, and local residents.
However, please do not take the management of exotic aquatic plants
around your shoreline property into your own hands—you must contact the New
Hampshire Department of Environmental Services at (603)271-2248 or Amy.Smagula@des.nh.gov
before you consider removing any plants or putting any chemicals that you may
have seen advertised on the internet or in a catalog into the lake to get rid of
the weeds—not only is the application of herbicides by an untrained,
unlicensed person illegal, it jeopardizes the health and welfare of the lake and
those who recreate in it or get their drinking water from it.
What
is NH LAKES doing about exotic aquatic plants?
2010 marks the ninth year of the New Hampshire Lakes Association’s
(NH LAKES) highly effective and popular Lake Host courtesy boat inspection and
exotic plant prevention program. This
summer, approximately 500 Lake Hosts are staffing 90 boat ramps located
throughout the state in an effort to prevent the spread of exotic plants.
You may have already run into one of these blue-shirted Lake Hosts at
your favorite boat ramp offering to show you how to inspect your boat, trailer,
and recreational gear to remove hitchhiking exotic aquatic plants.
Since 2002, hundreds of paid and volunteer Lake Hosts have inspected
almost 300,000 boats and trailers and have removed 813 fragments of exotic
aquatic plants that were about to enter or had just left a waterbody.
In addition, the number of future exotic species “saves” that Lake
Hosts have made by simply educating boat owners about how to prevent the spread
of exotic plants into New Hampshire’s lakes is immeasurable.
What
you can do to prevent the spread of milfoil and other nuisance plants.
Even if you use a boat ramp this summer that is not staffed by a Lake Host (or
if you don’t use a ramp at all), you can help prevent the spread of exotic
plants by following these simple steps:
* Clean your boat, trailer, and recreational of all aquatic vegetation each time
before entering or after leaving a waterbody, even if a Lake Host isn’t
present to help you.
* Avoid weed patches and areas designated as “Restricted Use Areas” while
boating. This will reduce the
chances of spreading the weed to other parts of the lake.
Remember, any broken piece of milfoil can start a new plant.
* Remove all fragments of plants that show up on the shoreline and dispose or
compost them in an area where they will not float back into the lake.
* Educate your neighbors, renters, and any new property owners in the
neighborhood about exotic species and what they can do to prevent their spread.
* Become a “Weed Watcher” and report any suspected exotic speces
infestations you find in surface waters to the New Hampshire Department of
Environmental Service at (603) 271-2248 or Amy.Smagula@des.nh.gov.
Thank
you for your help in keeping New Hampshire’s lakes and ponds milfoil-free!
For information about how to participate in the NH LAKES Lake Host program, visit www.nhlakes.org or contact Andrea LaMoreaux, NH LAKES Education Director, at alamoreaux@nhlakes.org or (603) 226-0299.
NH LAKES is a statewide, nonprofit, member-supported organization dedicated to protecting New Hampshire’s lakes for the safety and enjoyment of current and future generations. For more information on the organization’s lake protection efforts across the state and how to help, please visit www.nhlakes.org or contact (603) 226-0299. To receive NH LAKES’ free monthly e-news blast, Shorelines, full of interesting lake-related information, sign up on the website.
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Variable milfoil, an exotic aquatic plant, can make boating unpleasant by
fouling boat propellers.