Scotch Thistle

plants produce 8,400 to 40,000 seeds.
reduces forage production and virtually prohibits land utilization for livestock. The only animal known to graze this plant is a goat.
has been credited with helping Scotland fend off Viking invasion. As the Vikings moved into Scotland for a sneak attack, they yelled out in pain when they stumbled through thistle plants.

Small areas can be eradicated by digging. Plants must be cut off below the soil, leaving no leaves attached. Mowing has limited effect; it usually prevents seed production if done prior to flowering or when plants are just starting to flower. Mowing too early will only delay flowering. If plants are cut too late in the flowering stage, viable seed can still develop. Because there can be a wide variety in the maturity of plants, a single mowing is not likely to provide satisfactory control.
Establishing and maintaining dense, vigorous, competitive pasture can effectively prevent establishment. Healthy pasture is particularly important in the autumn, when most Scotch thistle seeds germinate.
There are herbicides on the market that, if applied correctly, have proven effective. Non-crop, grass-friendly products like Milestone, Redeem, Transline, Curtail, Escort, and Telar have proven to be the most effective. Late season treatments of Telar may temporarily injure cool season grasses. Other products such as those containing 2,4-D or Dicamba have also been used. Herbicides are best applied when the weed is in the rosette through bolt stage. Always read and follow the label when using any herbicide.