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SPOTTED KNAPWEED
 HISTORY
Spotted knapweed is native to Europe. It is believed that it entered Canada in 1893 and is now distributed through out many portions of Canada and the United States.
Estimates show that Spotted knapweed now infests nearly two million acres in Montana.
It probably found its way to Park County via the Northern Pacific Railway and the associated construction equipment that the railroad used for crushing and hauling rock at the Merriam Quarry just south of Emigrant. The firm that had the rock contract worked the Merriam site and a site near Clinton, Montana, in the heart of Montana's Knapweed. The infestation in Park County has generally radiated from the quarry with the help of man and machine.
HABITAT
Spotted knapweed infests soils of all types but especially likes well-drained soils, which are common in Paradise Valley. It tends to grow in open and disturbed areas but will take over range sites no matter what their condition. Spotted knapweed can and will take over a range site unless control activities are undertaken by the landowner. Housing development sites are ideal for Knapweed because of the disturbance, vehicle traffic, and over or under grazed rangeland. Also these development sites tend to be on well-drained areas. Until the sites are sold many times the developer has no long-term interest in the property and wants to keep his costs to a minimum.
GROWTH AND DEVELOPMENT
Seeds germinate in the fall or early spring when environmental conditions are suitable. First-year seedlings develop into rosettes. Maximum root growth occurs in this stage.
Plants that have wintered in the rosette stage, bolt in May or June and most bud by mid-June. Flowering occurs in July and August with mature seeds being formed by mid-August. Shedding of the seed occurs immediately, and if moisture is adequate, the seeds will germinate and develop into rosettes by fall.
Knapweed tends to be a long-lived biennial plant producing seeds for two or more years. The old stalks remain throughout the winter and that is one of the easiest times for identification and infestation assessment.
WATCH OUT FOR KNAPWEED PUBLICATION
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