Weed Prostrate knotweed, also known as knotgrass
Scientific Name Polygonum aviculare
Family Buckwheat family (Polygonaceae)
Life Cycle Summer annual
Reproduction Method Reproduces by seed
Appearance During early spring, knotweed resembles a grass with long, dark green leaves when germinating. Later, it forms a flat mat up to 2 feet in diameter on slender wiry stems; and emerges from a taproot. There are papery sheath at each node that give stems a knotted or swollen appearance.
Leaves The leaves are alternate; small, narrowly oval; dull, bluish green; and up to 1 1/4 inches long and 1/3 inch wide.
Flowers Flowers are small, borne in clusters in leaf axils. The buds are purplish opening to white to yellow flowers during June through October.
Occurrence Knotweed is found in compacted, infertile soils or thin turf in sun; often next to heavily trafficked walks or drives or over-used play or athletic sites. It germinates in early spring and continues growth through autumn.
Non Chemical Control Control knotweed by reducing soil compaction; by maintaining turf density and health through proper culture; and by mechanically pulling it.
Chemical Control
Application Period Apply preemergence herbicides before germination in spring; apply post emergence in mid spring through late summer when plants are young and actively growing.
Active Ingredient in Labeled Products

Preemergent

Postemergent

  • benefin
  • dithiopyr
  • isoxaben
  • pendimethalin
  • prodiamine
  • trifluralin
  • 2,4-D
  • 2,4-DP
  • chlorsulfuron*
  • clopyralid
  • dicamba
  • MCPA
  • MCPP
  • triclopyr
*not on tall fescue or ryegrass turf
Notes

(Click on Image to Enlarge and Sharpen Photograph)

Knotweed seedling

Knotweed mature plant

Knotweed stand

Knotweed along sidewalk

Knotweed taproot

Knotweed nodes on stem

Confused?? Look-a-Likes