Spring tillage eliminates established thistle rosettes before they produce seed. The economic impact of musk thistle is greatest in pastures and rangeland. Moderate infestations of musk thistle have been reported to reduce pasture yields an average of 23 percent. Livestock won't graze around musk thistle plants or in heavily infested areas. Back To Top Integrated Control Tactics for Management Chemical Control Herbicides should be applied when the musk thistles are in the rosette stage during fall or early spring.
Applications made after the plants begin to flower are too late to provide adequate control.
Plants treated with herbicide after the onset of flowering may still produce viable seed. Mechanical Control Mowing can reduce the amount of seed produced, but often enough stem remains intact with the crown to produce flowers and seed. Mowing within two days after the terminal flower head blooms effectively inhibits seed production and reduces some branching of the remaining plant stems. Since thistles in a field do not all mature uniformly, mowing will usually need to be repeated to prevent seed production. Mowing on poor soil may actually reduce the competitive effect of other plants, thus favoring musk thistle seedling survival.