Japanese Knotweed (Fallopia japonica)

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  • Native to eastern Asia
  • Small green-white flowers grow in showy plumes off stem and leaf joints
  • Stems are hollow and bamboo-like, with reddish-brown speckles
  • Leaves are heart-shaped and 8-10 cm across
  • Zig-zag pattern of leaf arrangement on the stem
  • Grow just about anywhere including waste sites, along roads, in meadows and wooded areas and along streambanks

Consequences of Invasion

  • Dominate stream banks
  • Increases erosion
  • Degrades wildlife and fish habitat
  • Reduces sight lines and block access to water bodies for recreation
  • Can grow over 3 m in a year
  • Able to grow through cement, house foundations, and walls
  • Extensive root systems are capable of resprouting even after many years of control
  • Roots can break off and float downstream to form new infestations

Prescription for Control

  • Cutting is not effective
  • Most effective way to eliminate it is to use a stem injector to inject stems with herbicide
  • Very important to control sprouts in new areas
  • Will not compost effectively
  • Must be bagged and buried deep in a landfill
  • Must be managed consistently through the growing season

More information available:

TIPS Sheet