Knotweed

knotweed plant
knotweed habit
knotweed-plant-2019
knotweed-stem-2019

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.

 Treatment Timeline


JanFebMarAprMayJuneJulyAugSeptOctNovDec
Control











RemovalNot recommended.  Plants regrow from stem and root fragments
Cut + Herbicide


Cut and treat stumps.  Bag all plant parts and dispose in the trash


Herbicide











Growth











Vegetative











Flowering











Seed