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: Smartweed stem showing sheathing stipules at the nodes
Photo by: J.A. Kropf
  
Weeds : Smartweeds : Polygonum spp.
(revision date: 4/5/2016)

Family: Polygonaceae
Cycle: Annual/Perennial
Plant Type: Broadleaf

Biology
Smartweeds are typically annual weeds with erect or spreading stems up to 3 feet long. The leaves are alternate, attaching to the erect or sprawling stems at enlarged nodes. Many smartweeds have a papery or clear membrane as part of the sheath where the petiole attaches to the stem. The small flowers of smartweeds are typically borne in short spikes or clusters arising in the leaf axils or at the tips of branches. Ladysthumb or spotted smartweed (P. persicaria) is one common species. Although most smartweed species have leaves are uniform in color, ladysthumb has a purplish spot or "thumbprint" at the center of each long, pointed leaf. Other species of interest include water smartweed (P. amphibium), a perennial which reproduces by seeds and from roots and is found in water or wet areas, and smartweed or water pepper (P. hydropiper), an annual species found in pastures, cultivated areas, and waste areas.
Habitat
Smartweeds can be weeds in cultivated areas, roadsides, waste areas, and other sites, depending on species. They are often found in moist sites including irrigated pastures.

Management Options

Non-Chemical Management
None recommended
Select non-chemical management options as your first choice!

Chemical Management

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
    Turf areas
    • 2,4-D + MCPP + dicamba
    Bare ground areas
    • products containing dicamba
    Images

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    Caption: Smartweed stem showing sheathing stipules at the nodes
    Photo by: J.A. Kropf
    Caption: Smartweed
    Photo by: T.W. Miller
    Caption: Smartweed flowers
    Photo by: T.W. Miller
    Caption: Smartweed leaves
    Photo by: J.A. Kropf