Timing is everything. That's particularly true with thistle control. And October to early November is one of the best times to use herbicides.
Did you have thistles this year? If so, walk out in those infected areas this week. I'll bet you find many thistle seedlings. Most thistle seedlings this fall will be small, in a flat, rosette growth form, and they are very sensitive now to certain herbicides. So spray this fall and thistles will not be a big problem next year. Several herbicides are effective and recommended for thistle control. Maybe the most effective is a newer herbicide called Milestone. Two other very effective herbicides are Tordon 22K and Grazon. But be careful with Tordon and Grazon since they also can kill woody plants, including trees you might want to keep. 2,4-D also works 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 Banvel or dicamba to the mix.
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