Eurasian water-milfoil (Myriophyllum spicatum) By: Melissa Negron

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Eurasian water-milfoil (Myriophyllum
spicatum)By Melissa Negron
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What we learned in class

• An aquatic perennial weed
• Introduced in Chesapeake bay in the 1880s is now
  widespread throughout the U.S.
• Spreads primarily by plants fragments
• Economic Impacts
• Decrease in recreational activities Ex.) Fishing
• Clog irrigation, carrals, gates
• Decrease in hydroelectric generation by clogging
  intake pipes

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Where did it come from?

• Native to Europe and Asia and Northern Africa.
• Accidentally introduced to the United States
  between the 1800s 1940s.
• 40 species of Myriophyllum in the world.
• Presently found in 44 of the 50 states.

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Where does it grow?

• Found in aquatic habitats reservoirs, rivers,
  natural lakes, freshwater and brackish estuaries.

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Identification

• 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.
• If the water is clear root plants grow 25-30
  feet.
• If removed from water the leaves collapse around
  the stem.

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Reproduction

• 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.

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Introduction

• 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

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Map (cont.)

• 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).

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Problems

• 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
• Widely Distributed Difficult to control
• Considered one of the worst weeds in the West
• Category A Weed in Nevada
• Limited in Distribution
• Codes Statutes will do whatever possible to
  eradicate.

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Management Prevention

• 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.
• Herbicides for aquatic weeds are questionable but
  triclopyr and 2,4-D appear to be effective.
• Other Methods
• Harvesting
• Diver Dredging
• Installation of Bottom Barriers
• Rotovation
• Sterile grass carp
• Milfoil weevil
• Limited situations

• Identifying natives and invasive non-native.
• Remove plant matter from boats.

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Predicting Invasion Success of Eurasian Water
milfoil

• J. Aquat. Plant Manage 36 28-32 (1998)
• 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

• 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).

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Predicting Invasion Success of Eurasian Water
milfoil

• Results
• 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 Carlsons Trophic State Index of 45-65 were
  most at risk of dominance by Eurasian water
  milfoil.

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Results
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Citations

• 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/m
  echcons.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/mil
  foil.html April 13, 2010.

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Question????????