Black Henbane
Buffalobur
Canada Thistle
Common Crupina
Dalmatian Toadflax
Diffuse Knapweed
Dyer's Woad
Field Bindweed
Hoary Cress
Johnsongrass
Jointed Goatgrass
Leafy Spurge
Matgrass
Meadow Hawkweed
Meadow Knapweed
Milium
Musk Thistle
Orange Hawkweed
Perennial Pepperweed
Perennial Sowthistle
Poison Hemlock
Puncturevine
Purple Loosestrife
Rush Skeletonweed
Russian Knapweed
Scotch Broom
Scotch Thistle
Silverleaf Nightshade
Skeletonleaf Bursage
Spotted Knapweed
Syrian Beancaper
Tansy Ragwort
Toothed Spurge
Yellow Starthistle
Yellow Toadflax
Idaho OnePlan recommends the website of the
Idaho Weed Awareness
Campaign as the best resource for up-to-date information about
Idaho's noxious weeds, and their control.
Source for this page:
Idaho's Noxious Weeds
by Robert H. Callihan & Timothy W. Miller
BACKGROUND
Russian knapweed (Acroptilon repens) is an invader from the Caucasus in southern Russia and Asia. It spreads both by seed and from shoots arising from creeping roots. It can produce up to 27 root shoots/ sq ft, and roots may grow to a depth of 23 feet. Russian knapweed causes chewing disease in horses.
DESCRIPTION
Russian knapweed is a perennialPlant that lives for more than 2 growing seasons whose stems are considerably branched and up to 4 feet tall. Leaves are up to 6 inches long near the base of the plant, entireNot toothed or otherwise cut to few-toothed, and are smaller toward the top of the plant. The flower heads are about ½ inch in diameter and are borne on branch tips during summer and fall. The flowers may be white or pink to lavender-blue. Greenish to straw-colored bracts are tipped with a papery, pointed marginThe edge of the leaf. Ivory-colored seeds are tipped by plumesA hairlike or featherlike structure, often on a seed that fall off at maturity. Roots are dark brown to black.
DISTRIBUTION
Russian knapweed is found throughout the western U.S.
CONTROL
A biological control agent (a stem/leaf gall nematode) is available for control of Russian knapweed, but control levels have not been determined. Herbicides can provide excellent control.