WSU Extension


Weeds : Prostrate knotweed : Polygonum aviculare
(revision date: 4/7/2021)

Family: Polygonaceae
Cycle: Annual
Plant Type: Broadleaf

Use Integrated Pest Management (IPM) for successful weed management.

Prostrate knotweed is a low-growing plant with wiry stems and a thin taproot. Plants branch extensively at the base, with branches lying along the ground but not rooting. The alternate, blue-green leaves are narrow, typically not exceeding an inch in length and 1/4 inch in width. Leaf tips may be slightly pointed to rounded in outline. The petioles are very short. The greenish-white flowers are borne in leaf axils and are inconspicuous.
Prostrate knotweed is commonly found on compacted soils and may occur on waste areas, or in lawns, paths, and other areas in yards. It is frequently a problem on compacted or high-traffic areas in lawns.

Management Options

Non-Chemical Management
  • Cultivation (rototilling or hoeing) will effectively eliminate plants.
Select non-chemical management options as your first choice!

Chemical Management

Apply according to label directions. Glyphosate products should be applied as spot treatments only! NOTE: Some ingredients listed here are only available in combination. Read the label carefully on combination products to make sure the product is suitable for your specific situation.

Landscape areas
  • glyphosate
  • dichlobenil
  • trifluralin
  • products containing diquat
Turf areas
  • 2,4-D + MCPP + dicamba
Bare ground areas
  • glyphosate
  • products containing diquat
  • dichlobenil
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Caption: Prostrate knotweed leaves
Photo by: R. Parker
Caption: Prostrate knotweed
Photo by: R. Parker
Caption: Prostrate knotweed flowers and leaf axils
Photo by: D.G. Swan
Caption: Prostrate knotweed seedling
Photo by: J.A. Kropf
Caption: Prostrate knotweed growing in gravel
Photo by: T.W. Miller
Caption: Prostrate knotweed flowers and nodes
Photo by: T. W. Miller
Caption: Prostrate knotweed leaves
Photo by: T. W. Miller