The season to watch for spotted knapweed has arrived according to Eldon Cole, University of Missouri extension livestock specialist.
“Knapweed is fairly easy to spot now as it’s 2 to 4 feet tall with a pale green color and buds are just beginning to form. The pink to purple flower start appearing in mid-June and that’s when most people will be able to positively identify it,” said Cole.
Spotted knapweed was added to the Missouri noxious weed list in the recent legislative session.
Although it is a relative newcomer to the weed scene in southwest Missouri – having first been noted along area roads in 2002 – spotted knapweed has been a serious pasture pest in northern and western states for years.
“The plant is a perennial that is a prolific seed producer. Knapweeds begin as a rosette and then send up a seedhead with blooms the next year. A number of herbicides will control it when applied between the rosette to mid-bolting stage,” said Cole.
According to Cole, the pest is highly invasive and crowds out desirable pasture and hay species. The plant actually exudes a toxin called catechin which kills other plants within its root zone.
MU Extension specialists have been monitoring locations with spotted knapweed the last few years to track spread the spread of the weed. Persons locating knapweed are asked to notify University Extension’s county office.
“We’ll not be able to eradicate the weed, but it’s not so prevalent yet that we can help reduce its spread into pastures,” said Cole.
For more information contact Cole at 417-466-3102. Pictures of knapweed can be found at extension.missouri.edu/lawrence/spotted_knapweed_in_missouri.htm.