|
Key identifying traits
Large, alternate leaves broadest at the leaf base-they resemble
rhubarb leaves
Erect, multi-branched coarse stems in 2nd year
Numerous, inconspicuous purple flowers mostly at branch ends
Marble sized burs are covered with many slender, hooked spines that
gave rise to the idea for ‘Velcro’
Stout, solid fibrous stems and tap root are so tough they are
difficult to cut
Biology and ecology
- A biennial growing 3 to 10 feet tall in 2nd year
- First year leaves are thickly hairy on underside
- Second year leaves wrinkled, wavy & less hairy
- Found on roadsides, ditch-banks, next to streams, in pastures and
in waste areas
- Stout plant skeletons with burs are still evident the next year
after growth
- Burs spread by clinging to clothing and animals
Control
Prevention – Learn to
identify plants; know your property; beware of fill dirt and seed from
outside your area and clean and properly dispose of burs from domestic
animals and clothing
Biological – None known to date
Cultural – Good vegetative cover helps lessen infestation
potential but won’t completely stop it
Mechanical – Will not stand repeated cultivation, cutting,
digging and pulling are difficult but effective; properly bag and
dispose mature burs
Chemical – Several effective at label rates; adjuvants increase
up-take and effectiveness.
Refer to the
PNW Weed Management Handbook for specific chemical recommendations |
the "burs" after flowering
|
