University of Maryland Extension

Knotweed

(More lawn weeds)

Knotweed
Polygonum aviculare

knotweed
Photo: Knotweed, Polygonum aviculare
Robert Vidéki, Doronicum Kft., Bugwood.org

General description

Knotweed is a summer annual broadleaf weeds that spreads by seed. Is low-growing and has wiry stems that form a mat. Leaves vary in shape depending on the maturity of the plant. Juvenile leaves are dark green and are long and slender. Older leaves are smaller and are duller green in color. Leaves are alternate along the stem. Small white or yellow flowers are inconspicuous and are located at the leaf axils. Blooms midsummer through the fall.

Knotweed growing in soil
Robert Vidéki, Doronicum Kft., Bugwood.org 

Conditions that favor growth

It grows in areas with heavily trafficked, compacted soils.

knotweed closeup
Close up details
Bruce Ackley, The Ohio State University, Bugwood.org

Management In Lawns

  • Cultural practices
    Maintain healthy, dense turf that can compete and prevent weed establishment.

  • Mechanical Management
    Hand pulling or using an appropriate weeding tool are the primary means of mechanical weed control in lawns. This is a viable option at the beginning of an infestation and on young weeds. Hand pulling when the soil is moist makes the task easier. Weeds with tap roots like dandelions or have a basal rosette (leaves clustered close to the ground) like plantain are easier to pull than weeds such as Bermudagrass (wiregrass) or creeping Charlie (ground ivy) that spread with stolons or creeping stems that root along the ground.

  • Chemical Treatment in Lawns 
    Herbicides should be used as a last resort because of the potential risks to people, animals, and the environment. Be aware of these precautions first. 
    If you chose this option, spot treat weeds with a liquid, selective, postemergent, broadleaf weed killer applied when weeds are actively growing. Look for a product with one or more of the following active ingredients: 
    2, 4-D, MCPP (mecoprop), Dicamba* or Triclopyr.

    *Do not spray herbicides containing dicamba over the root zone of trees and shrubs. Roots can absorb the product possibly causing plant damage. Refer to the product label for precautions. 

  • Organic Lawn Herbicides

                                                                                               

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