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 | Creeping Jenny | 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 | Lesser celandine | Liverworts | Mallow, common (Cheeseweed, Buttonweed) | Nightshades | Oxalis (Creeping woodsorrel) | Parrotfeather and Eurasian watermilfoil | Pineappleweed | Plantain (Broadleaf, Buckhorn) | Poison hemlock | Poison ivy and Poison oak | Pokeweed | 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 |
|
|
|
|
|
Caption: Giant hogweed patch
Photo by: Washington Noxious Weed Control Board
|
|
Weeds : Giant hogweed : Heracleum mantegazzianum
(revision date: 6/9/2014)
Family: Apiaceae (Umbelliferae) Cycle: Perennial Plant Type: Broadleaf
Use Integrated Pest Management (IPM) for successful weed management.
Biology
Giant hogweed is a short-lived perennial plant, typically surviving 2 to 5 years. The hollow stems are robust (two- to four-inch diameter), hairy, ribbed, and blotched with purple. The stems have distinct, protruding white hairs that are especially noticeable at the nodes and the base of the leaf stems. The alternate leaves may reach five feet across and are deeply lobed or toothed. Leaf stems also have purple blotches. The flat-topped flower heads are umbrella-shaped and may reach over two feet across; individual flowers are small and white. Plants usually die after they bloom and produce seed. Superficially, giant hogweed resembles the native cow parsnip (Heracleum maximum), but there are two distinct differences. Cow parsnip is typically only 3 to 8 feet high, while giant hogweed grows 10 to 15 feet high. Also, the undersides of cow parsnip leaves have soft, wavy, shiny hairs. Giant hogweed leaves have stiff, dense, very short hairs on the underside.
SPECIAL INFORMATION: Avoid skin contact with sap. Skin contact with giant hogweed sap, followed by exposure to sunlight, can result in a photosensitive reaction in some people. Symptoms include painful, burning blisters which can develop into purplish or blackened scars. Eye contact with sap can result in temporary or permanent blindness. In WASHINGTON, giant hogweed is designated as a Class 'A' noxious weed. Eradication of the weed is REQUIRED by state law! In OREGON, it is designated as both a Class 'A' noxious weed and a target or 'T' weed subject to priority prevention and control. Eradication or intensive control may be required in your county. In addition, giant hogweed is on the noxious weed quarantine list for both Washington and Oregon. Sale, purchase, and transport of plants, plant parts, and seeds is prohibited. Consult your local Noxious Weed Control Board for more information.
|
|
Habitat
Giant hogweed can be found in damp areas.
Non-Chemical Management
- Careful digging is useful to manage weed populations. However, digging can carry undesirable weed seed to the surface and foster further germination.
- Cut the stems at the base to remove flower and seed heads prior to seed dispersal.
Select non-chemical management options as your first choice!
Chemical Management
Apply according to label instructions. Glyphosate products should be applied as spot treatments only! Do not touch the weed with bare hands, as it is toxic to skin. 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.
|
Images
+ Show larger images
|
Caption: Giant hogweed patch
Photo by: Washington Noxious Weed Control Board
|
Caption: Giant hogweed flowers
Photo by: Washington Noxious Weed Control Board
|
Caption: Giant hogweed hollow stems
Photo by: Washington Noxious Weed Control Board
|
|
|
|