Prostrate Knotweed

Prostrate knotweed seedling
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Prostrate knotweed seedlings Prostrate knotweed plant Prostrate knotweed stem and node
Prostrate knotweed seeling and ochreas Prostrate knotweed flowering stem Prostrate knotweed flower


An annual weed, reproducing by seeds. Stems are prostrate to semi-erect, wiry, leafy, and have thin papery sheaths (ocrea) at each joint. The leaves are alternate, dull, blue to green in colour, hairless, and tapered toward the tip and base. They are widest near the middle, 1-6.5 cm long and 3-8.5 mm wide. The flowers are small, inconspicuous, lack petals, and occur in clusters at leaf axils. The seeds are slightly rough, about 1.5 mm long, 3-sided, and reddish-brown in colour.

Prostrate knotweed grows well on compacted soils, especially roadsides and walking paths.

Scouting Techniques

Take a minimum of 20 weed counts across the field.

Effects On Crop Quality

Prostate knotweed can indirectly affect the development of field crops because it is a host for dodder and powdery mildew.

Control Tips

  • cultivation
  • hoeing/hand pulling
  • Groups 3 & 4