Musk Thistle

Description-- Usually this thistle is a biennial, but sometimes it is a winter annual or annual. Stems are erect, spiny with spiny wings, and 3 to 6 feet tall; the lower portion is branched. Stems and branches are densely covered with short hairs. Spiny, coarsely-toothed leaves alternate down the stem. Flower heads are as much as 2” across, on the ends of long, nearly naked stems, frequently drooping or nodding. The flowers are purple or lavender; spiny-tipped bracts surround the head. Seeds are about .19 inch long, glossy yellowishbrown; pappus is hairlike.

Adaptation --Musk thistle is locally abundant to moderately infrequent in pastures, prairie ravines, hillsides, open wooded stream valleys, fields, roadsides and waste areas.

Life History --Musk Thistle germinates in the spring and fall and spends 90 percent of its life cycle in the rosette stage. Most plants bolt in May-June and flower during the summer. Musk thistle is a prolific seed producer and readily invades site with disturbed soils. Seedling mortality is the greatest in late spring and summer. Plants that germinate late in the fall often have greater mortality, lower growth rates, flower later and produce fewer seeds/plant.

Management Options

 1. Prevention— Reduce new infestations by planting weed free seed, using livestock feed free of Musk thistle seed, and cleaning equipment before leaving infested areas.

2. Cultural and Mechanical Practices— Mowing, hand cutting, hand digging and the removal of heads are practices for control of musk thistle.

3. Biological Control— Biological controls available includes insects, parasites and disease causing organisms. For current recommendations contact Kansas State Board of Agriculture.

4. Recommended Treatments:

 2,4-D .5 gallon/acre

Roundup (Glyphosate) 1 gallon in 2 gallons water to get a 33% solution—apply with a roller

Tordon 22k (Picloram) 6 to 8 oz/acre for fall treatment

Tordon 22k (Picloram) + 2,4-D -- .5 pint Tordon + .25 gallon 2,4-D/acre for spring treatment

Escort (Metsulfuron) + 2,4-D -- .5 oz Escort + .25 gallon 2,4-D/acre

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