Download Eurasion water-milfoil (Myriophyllum spicatum L.)

Eurasian water-milfoil (Myriophyllum
spicatum)
By: Melissa Negron
What we learned in class
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An aquatic perennial weed
Introduced in Chesapeake bay in the 1880’s is now
widespread throughout the U.S.
Spreads primarily by plants fragments
Economic Impacts
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Decrease in recreational activities Ex.) Fishing
Clog irrigation, carrals, gates
Decrease in hydroelectric generation by clogging intake pipes
Where did it come from?
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Native to Europe and Asia and Northern
Africa.
Accidentally introduced to the United States
between the 1800’s &1940’s.
40 species of Myriophyllum in the world.
Presently found in 44 of the 50 states.
Where does it grow?
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Found in aquatic habitats;
reservoirs, rivers, natural
lakes, freshwater and
brackish estuaries.
Identification
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Feather-like leaves found in
whorls around the stem.
Mature leafs have 12 or more
pairs of leaflets.
Native milfoil have less than 12
pairs of leaflets.
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If the water is clear root plants
grow 25-30 feet.
If removed from water the
leaves collapse around the
stem.
Reproduction
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Able to reproduce rapidly and successfully
through the form of plant fragments.
During late summer and fall the plant
becomes brittle and breaks apart.
The distribution of these fragments float into
new areas and establish as a new plant.
Introduction
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According to Couch and Nelson
the first documentation of
Eurasian water-milfoil was
collected in October 1942 from
a pond in Washington D.C.
Easily spread by fragmentation
Water bodies of boats & boating
activities
Commonly sold an aquarium
plant
Accidentally Introduced
 Colombia River
Map (cont.)
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First reported from Nevada, September 1995, from marinas along the
northern shore of Lake Tahoe (Anderson and Ryan 1996). Uncommon in
ditches and at lake margins in regions surrounding San Francisco Bay and
San Joaquin Valley, California (Hickman 1993).
Problems
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Upon invasion of new
territories this plant reduces
the species diversity.
Alters water body ecology
Forms dense mats of
vegetation on surfaces of
water which interfere with
recreational activities.
Provides poor habitats for
fish and other wildlife
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Not on the U.S. Federal Noxious Weeds List
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Widely Distributed & Difficult to control
Considered one of the worst weeds in the
West
Category A Weed in Nevada
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Limited in Distribution
Codes & Statutes will do whatever possible to
eradicate.
Management & Prevention
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If invasion occurs almost impossible to
remove.
Herbicides such as Sonar, 2,4-D &
triclopyr-TEA are used in small bodies of
water to manage infestation.
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Herbicides for aquatic weeds are
questionable but triclopyr and 2,4-D
appear to be effective.
Other Methods
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Harvesting
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Diver Dredging
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Installation of Bottom Barriers
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Rotovation
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Sterile grass carp
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Milfoil weevil
 Limited situations
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Identifying natives and invasive nonnative.
Remove plant matter from boats.
Predicting Invasion Success of Eurasian
Water milfoil
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J. Aquat. Plant Manage 36: 28-32 (1998)
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John D. Madsen
Goal: To correlate limnological parameters to Eurasian milfoil
dominance & from those relationships develop estimates
predicting invasion success.
Tool in identifying & managing the spread of Eurasian water
milfoil.
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Predicting Invasion Success of Eurasian
Water milfoil
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300 lakes, 30 published, 14 unpublished
Lakes in Vermont, New York, Michigan, Wisconsin,
Minnesota, Washington, Oregon, Alabama, Ontario,
and British Columbia
1 year of data was collected for each lake
Plant Communities; aquatic plant species presence
and/or abundance, Eurasian water milfoil biomass,
Eurasian water milfoil percent cover, native plant
percent cover, Eurasian water milfoil cover area
littoral zone), native plant cover area (littoral zone).
Predicting Invasion Success of Eurasian
Water milfoil
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Results:
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Lakes with more than 50%
Eurasian water milfoil
dominance were found to have
less than 60% cumulative
native plant cover.
Lakes with a Total Phosphorus
of 20-60(μgL-1) or a Carlson’s
Trophic State Index of 45-65
were most at risk of dominance
by Eurasian water milfoil.
Results
Citations
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Madsen JD (1998) Predicting Invasion Success of Eurasian Water milfoil J. Aquat. Plant
Manage.36: 28-32
Mechanical Controls; (2003); Plant Management in Florida Waters;
http://plants.ifas.ufl.edu/guide/mechcons.html; April 17, 2010.
Stevens County Cooperative Extension; (2001); Stevens County Noxious Weed Control
Board http://www.co.stevens.wa.us/weedboard, April 13, 2010.
Washington State Department of Ecology; (2010); Non-native Invasive Freshwater Plants
http://www.ecy.wa.gov/programs/wq/plants/weeds/milfoil.html April 13, 2010.
Question????????