Knotweed

knotweed plant
knotweed habit

Knotweed

  • Bohemian knotweed
  • Giant knotweed
  • Japanese knotweed


Polygonum spp. (aka Fallopia spp.)

Information Sheet (PDF)

Colorado List A - Eradication required


General

  • Family: Buckwheat (Polygonaceae)
  • Introduced from Asia


Habitat

  • Colony forming
  • Found in wetlands, drainages, and rights-of-way
  • Perennial shrub
  • Very invasive
  • Was sold as an ornamental in the past


Common Names

  • Crimson beauty, Mexican bamboo, Japanese fleece flower


Plant


Vegetation

  • Leaves - smooth 3 - 4 inches wide and 4 - 6 inches long, somewhat oval shaped
  • Papery sheath at nodes
  • Plant 10 plus feet tall
  • Stems - hollow between nodes


Roots

  • Rhizomes spread up to 20 feet from plant
  • Roots up to 6 feet deep


Flower

  • July - September
  • Small, in groups that grow from leaf axis
  • White


Seed

  • Small, winged, 1/10 inch wide


Seedling

  • Plants re-sprout from roots in the spring


Reproduction

  • Plant Fragments
  • Rhizomes
  • Roots
  • Seed


Control


Biological

  • None


Chemical


Cultural

  • Prevention
  • Removal Not Recommended - If you decide to remove, make sure the entire  root is removed. Must be repeated as new plants emerge. Clip stalks in  early Spring and treat re-growth with herbicide. Bag and dispose of all  plant parts because any fragment may sprout. Do not compost or dispose  of as green waste.


Mechanical

  • Burning - N/A
  • Grazing - N/A
  • Mowing - Not recommended. Plants will resprout.


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