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: Tansy ragwort
Photo by: T. W. Miller
  
Weeds : Tansy ragwort : Senecio jacobaea
(revision date: 4/5/2016)

Family: Asteraceae (Compositae)
Cycle: Biennial
Plant Type: Broadleaf

Biology
Tansy ragwort is a biennial or short-lived perennial spreading by seeds. In lawns, regular mowing may maintain it in a non-flowering perennial form. First-year rosettes have a cluster of basal leaves. Second-year plants grow upright to two to four feet. Leaf shape varies greatly, with some leaves deeply lobed the full length of the blade and others lobed mainly near the base. The lobes are round-tipped and give the leaf a ragged or ruffled appearance. Leaves are alternate and dark green above and whitish-green beneath. The stout stems may be branched, or several stems may emerge from the base of the plant. Yellow flower heads are borne at the top of the branches in flat-topped clusters. Each 1/2-inch flower head has a yellow center and a fringe of 10 to 15 long "petals" or ray flowers at the edge. Common tansy (Tanacetum vulgare), often mistaken for tansy ragwort, has fern-like leaves and button-like flower heads that lack ray flowers. SPECIAL INFORMATION: Tansy ragwort is toxic to livestock in both fresh and dried forms. While animals typically do not graze on it, they may be unable to avoid it in dried hay. Ingestion causes irreversible liver damage and may taint milk and honey. In WASHINGTON, it is designated as a Class 'B' noxious weed. Control may be required in your county. In OREGON, it is designated as a Class 'B' noxious weed, as well as a target (T) weed. Target weeds are considered a priority weed for statewide management. Control of target species may be required in your county. Consult your local Noxious Weed Control Board for more information.
Habitat
Tansy ragwort is found primarily west of the Cascades. It grows in pastures, waste areas, and disturbed sites. It is not usually a problem in maintained lawn and turfgrass.

Management Options

Non-Chemical Management
  • Cultivation (rototilling or hoeing) will effectively eliminate plants.
  • Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.
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
Turf areas
  • 2,4-D + MCPP + dicamba
Bare ground areas
  • glyphosate
Images

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Caption: Tansy ragwort
Photo by: T. W. Miller
Caption: Tansy ragwort flowers
Photo by: T.A. Bertram
Caption: Tansy ragwort rosettes
Photo by: T.W. Miller
Caption: Tansy ragwort flowers
Photo by: T.A. Bertram
Caption: Tansy ragwort in spring
Photo by: T.A. Bertram
Caption: Tansy ragwort rosette
Photo by: T. W. Miller