The latest buzz - invasive species "Spotted Knapweed"

Spotted Knapweed has been "spotted" in Guernsey County.  Its been reported to our office in the Quaker City area, and also in the Cumberland area.
It is a short-lived perennial or biennial that grows 2-3 feet tall.  Seedlings develop the first year into lowgrowing rosettes.  From July to September it produces pink to purple flowers that look similar to thistles.  These flowers die down to brown seeds with with a plume of soft greyish bristles.   It infests hayfields, pastures and roadsides.  It is native to Europe and Asia.  It has a long taproot, and the plant exudes a toxin that kills neighboring plants' roots.   Since this toxin can irritate some people's skin, care should be taken when working with it. 
Sheep and goats will readily graze this weed when it is in the young growth stage.  As it matures, it becomes less palatable as bitter compounds called cnicin build up in the plant.  A diet of more than 70% knapweed can cause health issues. 
Over time, grazing will weaken the plant.  This means of control is most effective when used in combination with chemical controls.  It is very effective in reducing seed production when grazed twice, once at the rosette to bolt stage, and again at the bud stage. 

(this info from the American Sheep Industry)