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Eurasian Milfoil
Milfoil reproduces extremely rapidly and can
infest an entire lake within two years.
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Eurasian watermilfoil
(Myriophyllum spicatum) is actually a very attractive plant with a somewhat feathery
underwater foliage. Believe it or not, this often loathed species was once commonly
sold as an aquarium plant. Indeed it is a beautiful formed plant with very delicate
profile but this naturally appeal is lost when pond and lake owners are confronted
with a huge area of infestation or choking tentacles of this plant. Eurasian watermilfoil,
or sometimes called just milfoil, originates from Europe and Asia, but was introduced
to North America many years ago and is now found over much of the Canada and the
United States. This plant was introduced to North America as long ago as the 1940s,
but it may have actually arrived as early as the late 1800s.
While the
chemical control of Eurasian Milfoil is always possible with the use of strong
chemicals; more and more people want to get rid of Eurasian Milfoil naturally
without using any harmful chemicals. The pond owner of today, confronted with
weeds or un-wanted algae growth, tens to want to clear the pond and remove these
weeds naturally without using harsh chemicals that can kill fish and destroy the
shoreline wildlife habitat.
Aeration can be very good for tool in assisting with
the controlling of milfoil, but it needs to be effective and well-placed aeration.
I've seen many friends and clients who want to build a cheap DIY aeration system
who buy a 1/4 HP Gast compressor and run some poly pipe into their pond with a
cheap airstone sitting in a bucket of rocks and they are convinced that this is
the type of aerator that the gang of buddies at PondBoss.com would recommend to
set up a cheap aerator! Sure there are ways to add aeration to a pond or even
a lake, we've aerated some large 25 acre lakes with no problem...well...it costs
a lot of money to fix the problems of blue-green algae and do what they call bio-dredging
with the combination of natural liquid bacteria and aeration systems. Of course
many companies are flaunting their dry bacteria but the dry bacteria mixes on
the market today are so variable that you must be careful which pond bacteria
you buy! It is best to check the reviews of the product you buy and often the
reviews are provided by the manufacturers or the distributors....if you have any
questions on the quality of the bacteria you want to put in to your pond feel
free to contact us to help decide if it is worth the money they want to take from
you!.
We have a black-list of dealers and stores who are attempting to
sell poor quality enzymes and cultures and a list of those reputable suppliers
of natural pond bacteria who sell retail and wholesale. Pond dyes and pond dyes
with enzymes sound like they can create conditions that reduce or eliminate the
Eurasian Milfoil and other aquatic weeds and algae but be careful when choosing
this inexpensive solution as it often requires repeat treatments!
But
regardless of the claims of natural bacteria for controlling weeds we must understand
that using liquid or dry bacteria cultures for eliminating or controlling Eurasian
Milfoil you should be prepared for a long term treatment and not a miracle cure.
Poison chemicals will work quickly but they will also kill frigs, fish and endanger
pets. Undertaking a long-term and natural approach to dealing with the unwanted
growth in your pond requires more patience but also is the winning strategy in
the long run! How does the installation of an aerator, in a large lake for example,
address the problem of aquatic weeds?
As we have seen aeration can be
very good at controlling Eurasian Milfoil, however it needs to be effective and
efficient aeration. When we talk about effective or efficient aeration we mean
that such aeratio can assist in nutrients like phosphorous adhering to other elements
and precipitating out of the system–thus leaving nutrients like phosphorous unavailable
as a nutrient source for the Eurasian Milfoil, often a food source for lakes and
ponds with Blue Green Algae.
Along
with the side reduced amount of available P or phosphorous for un-wanted plant
growth – the addition of aeration and circulation promotes many other effects.
One thing it will do is to keep the nutrients and organic molecules in suspension.
By keeping these organic molecules; that is leaves and bottom muck and smelly
pond bottom muck in suspension; beneficial microbes, wether added or by supplemental
growth due to the addition of oxygen or from the addition of an aerator will have
a positive effect.
Microbes are better at competing for soluble nutrients
than are typical pond plants which means you have competition for food and nutrients
adding a second component to the "control" equation. The circulation caused by
the aeration system, whether it is a turn-key system or a homemade aeration system,
will have an effect on the Eurasian Milfoil, however we have yet to see that there
is proof beyond a reasonable doubt that Eurasian Milfoil can be controlled by
the use of a simple aeration system. From what we have seen, simply moving the
water, or creating the circulation effect by adding a bottom mounted diffuser,
does not alter the ecosystem of a pond enough to make generally slow the intrusion
of the Eurasian Milfoil species.
With the addition of a shore mounted
air-compressor and an efficient diffuser system you will find that this creation
of movement is the most crucial factor in controlling Eurasian Milfoil. There
is no real conclusive evidence to conclude that the addition of moving water will
eliminate the growth of Eurasian Milfoil but the alteration of the ecosystem by
the addition of the water movement of an aerator that will eliminate any stagnant
waters and once that happens more natural organisms are able to thrive and while
Eurasian Milfoil doesn't have any natural predators there can be natural insects
like mites that will feed on them! Let us look at how the circulation component,
which also adds a considerable amount of oxygen, can create a positive alteration
of the aquatic ecosystem.
While it can promote a continuation of the
natural pond and lake turn-over cycles and helps to control, but not eliminate,
Eurasian Milfoil though does not have structures designed to over-winter: There
is a shortage of pertinent information regarding controlling string algae, matt
algae and other nuisance plant growth and we have seen more and more people looking
for alternative treatments for Eurasian Milfoil as opposed to using harsh poisons
and chemicals and algaecides. We are seeing more and more people using the benefits
of aeration and water circulation to help slow and somewhat control the infestation
and spread of Eurasian Milfoil.
A long term approach is the best approach;
dealing with issues of shoreline erosion are a good start as is the entire management
of the watershed. Practices that avoid the influx of Phosphorous will help as
will helping reduce bottom muck and build-up on the pond bottom; thus, using beneficial
bacteria and aeration, while it may not be the miracle cure that most of us are
after, it is still one of the best long-term approaches to dealing with this pesky
plant! A good supportive strategy of lake management has, in many cases, been
able to transform a milfoil infested lake into a thriving and very beautiful aquatic
habitat.
Patience...
Eurasian Milfoil Websites
Here are some websites we recommend if you are looking for more information.
Washington State Department of Ecology
http://www.ecy.wa.gov/programs/wq/plants/weeds/milfoil.html
Once milfoil becomes well-established within a waterbody, it is difficult or impossible
to remove. In smaller waterbodies (350 acres or less), we have had some limited
success using an aquatic herbicide called Sonar® to remove milfoil. Recently the
state legislature gave limited approval for the use of 2,4-D to control pioneering
milfoil infestations. Other control methods include: Harvesting, rotovation (underwater
rototilling), installation of bottom barriers, diver hand pulling, diver dredging,
and in some very limited situations the use of triploid (sterile) grass carp.
We are investigating other biological controls such as the milfoil weevil. The
management of milfoil costs the state and private individuals up-to-one million
dollars per year.
Other
Federal Government Websites
Eurasian
Water Milfoil
USDA.
APHIS. Cooperative
Agricultural Pest Survey. National Agricultural Pest Information System.
Photographs;
Distribution; Special Note: Links to other sites Eurasian
Watermilfoil - Invasive Plants: Changing the Landscape of America
Federal
Interagency Committee for the Management of Noxious and Exotic Weeds.
Identification/Description;
Photographs; Introduction History; Impacts; Distribution Myriophyllum
spicatum
Integrated Taxonomic Information System.
Taxonomy Eurasian
Watermilfoil - Plant Invaders of Mid-Atlantic Natural Areas (2002)
DOI.
National Park Service and Fish and Wildlife Service.
Identification/Description;
Photographs; Distribution; Introduction History; Impacts; Controls Whole-Lake
Applications of Sonar for Selective Control of Eurasian Watermilfoil, Feb 2001,
ERDC/EL TR-01-7 (PDF | 895 KB)
United States Army Corps of Engineers.
Engineer Research and Development Center.
Controls; Research Eurasian
watermilfoil - Aquatic Plant Information System (APIS)
United States Army
Corps of Engineers. Engineer Research and Development Center. Environmental Laboratory.
Identification/Description; Introduction History; Impacts; Habitat; Distribution;
Dispersion; Controls Myriophyllum
spicatum L. (Eurasian Watermilfoil) - Noxious and Nuisance Plant Management Information
System (PMIS)
United States Army Corps of Engineers. Engineer Research
and Development Center. Environmental Laboratory.
Identification/Description;
Photographs; Introduction History; Impacts; Distribution Predicting
the Invasion of Eurasian Watermilfoil into Northern Lakes, Technical Report A-99-2,
Feb 1999 (PDF | 458 KB)
United States Army Corps of Engineers. Waterways
Experiment Station.
Controls; Research Foiling
Watermilfoil (Mar 1999)
USDA.
Agricultural Research Service.
Controls; Research Myriophyllum
spicatum Article Citation Search - AGRICOLA Database
USDA.
National Agricultural Library.
Research; Special Note: NAL
Catalog Search (resources) Myriophyllum
spicatum - Germplasm Resources Information Network (GRIN)
USDA.
ARS. National Genetic
Resources Program.
Taxonomy; Legal Aspects Eurasian
Watermilfoil - Biological Control of Invasive Plants in the Eastern United States
USDA. Forest
Service.
Taxonomy; Identification/Description; Photographs; Distribution;
Introduction History; Impacts; Life Cycle; Habitat; Controls
Plant Profile for Myriophyllum spicatum - PLANTS Database
USDA.
NRCS. National Plant Data Center.
Taxonomy; Illustrations; Distribution; Legal
Aspects
Myriophyllum
spicatum L.
DOI.
Florida Integrated Science Center.
Taxonomy; Identification/Description; Habitat;
Distribution; Impacts
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