WSU Extension

Hortsense

Weeds
 
Annual bluegrass 
Barnyardgrass 
Bentgrass, creeping 
Bermudagrass 
Bittercress (Shotweed, Hairy bittercress) 
Bittersweet nightshade (European bittersweet) 
Black medic 
Blackberry (Himalayan, Evergreen, Pacific) 
Blue mustard (Purple mustard, Tenella mustard) 
Brackenfern, western 
Buffalobur 
Bull thistle 
Buttercup, creeping 
Canada thistle 
Catchweed bedstraw (Cleavers) 
Catsear, common (False dandelion) 
Chickweed, common and mouseear 
Clover 
Comfrey 
Crabgrass 
Dandelion 
Dock (Curly, Broadleaf) 
Dodder 
Downy brome (Cheatgrass, Downy chess) 
Dwarf mistletoes 
English daisy (Lawn daisy) 
English ivy 
Field bindweed (Wild morningglory) 
Field pennycress (Fanweed) 
Flixweed 
Foxtail (Green, Yellow, Bristly) 
Garden loosestrife 
Giant hogweed 
Goldenrods 
Groundsel, common 
Hawkweeds 
Hedge bindweed 
Henbit 
Herb Robert (Robert geranium, stinky Bob) 
Horsetails (Scouringrush) 
Horseweed (Marestail) 
Knapweeds 
Knotweeds (Bohemian, Giant, Japanese, Himalayan) 
Kochia 
Lambsquarters, common 
Liverworts 
Mallow, common (Cheeseweed, Buttonweed) 
Nightshades 
Oxalis (Creeping woodsorrel) 
Parrotfeather and Eurasian watermilfoil 
Pineappleweed 
Plantain (Broadleaf, Buckhorn) 
Poison hemlock 
Poison ivy and Poison oak 
Prickly lettuce (China lettuce) 
Prostrate knotweed 
Puncturevine (Tackweed, Goathead) 
Purple deadnettle (Red deadnettle) 
Purple loosestrife (Purple lythrum) 
Purslane, common 
Quackgrass 
Red sorrel (Sheep sorrel) 
Redroot pigweed (Rough pigweed) 
Redstem filaree (Stork's bill, Crane's bill) 
Reed canarygrass 
Russian thistle (Tumbleweed) 
Ryegrass, annual (Italian ryegrass) 
Salsify (Goatsbeard) 
Scotch broom 
Shepherd's-purse 
Smartweeds 
Sowthistle, annual and perennial 
Speedwells 
Spurges (Prostrate spurges) 
St. Johnswort, common (Goatweed, Klamathweed) 
Stinging nettle 
Tansy ragwort 
Tumblemustard (Jim Hill mustard) 
Velvetgrass (Common velvetgrass) 
Velvetleaf 
Water primrose 
Waterhemlock, western 
Yellow nutsedge 



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Caption: Prostrate knotweed leaves
Photo by: R. Parker
  
Weeds : Prostrate knotweed : Polygonum aviculare
(revision date: 4/5/2016)

Family: Polygonaceae
Cycle: Annual
Plant Type: Broadleaf

Biology
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.
Habitat
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 and glufosinate 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
  • glufosinate
  • trifluralin
  • products containing diquat
Turf areas
  • 2,4-D + MCPP + dicamba
Bare ground areas
  • glyphosate
  • products containing diquat
Images

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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