As October starts to arrive, our thoughts naturally turn toward crop harvest, but don't forget this is the optimal timeto control thistles. They can be hard to see at this time, but that means they're small enough to provide for more successful control.
Timing is everything. That's particularly true with thistle control and the time from October to early November is one of the best times to use herbicides.
Walk out into areas where you know you had thistles this year. Look close and you're likely to find many thistle seedlings. Most thistle seedlings this fall will be small, in a flat rosette growth form. At this growth stage they are very sensitive to certain herbicides.
Several herbicides are effective and recommended for thistle control. Several newer herbicides like ForeFront, Milestone, and Chaparral work very well. Two other very effective herbicides are Tordon 22K and Grazon. Be careful with all these herbicides, but especially Tordon and Grazon, since they also can kill woody plants, including trees you might want to keep. Applications of 2,4-D work well while it’s warm, but you will get better thistle control by using a little less 2,4-D and adding a small amount of dicamba to the mix.
Other herbicides such as Redeem, Cimarron, and Curtail also can control thistles in pastures. No matter which weed killer you use, though, be sure to read and follow label instructions and spray on time.
Next year, avoid overgrazing your pastures so your grass stands get thicker and compete with any new weeds or thistle seedlings.
Controlling thistle this fall can help provide a clearner pasture next spring.