Eurasian Watermilfoil

Eurasian Watermilfoil

Myriophyllum spicatum

List B - Control required in Jeffco

General

  • Family:  Watermilfoil (Haloragaceae)
  • Introduced from Eurasia

Habitat

  • Colony forming
  • Found in creeks, ponds, lakes, irrigation ditches
  • Perennial submersed aquatic


Plant


Vegetation

  • Leaves 1/2-1 1/2 inches long. Usually in whorls of 4-12 paired leaflets 
  • Stems branched near water surface.  Fragment and moves easily to new areas

Roots

  • Rhizomes and fibrous roots on stem fragments

Flower

  • 4-parted on a spike 2-4 inches above watere
  • July to September
  • White to pink

Reproduction

  • Plant fragments


Control


Biological

  • None

Chemical

  • info sheet coming soon

Cultural

Draw down water over the winter to freeze the soil

Mechanical

Removal - all fragments must be removed

Use all chemicals according to the manufacturer’s label. No specific recommendation or endorsement is made or implied by listing methods or products.

Treatment Timeline


JanFebMarAprMayJuneJulyAugSeptOctNovDec
Control











Removal



Make sure all plant fragments are removed

Cultural








Water drawdown
Herbicide











Growth











Vegetative











Flowering











Seed





Seed has low viability