As October starts to arrive, our thoughts naturally turn towards crop harvest. But don’t forget, it’s also thistle time again. Even if they are hard to see, this is the time to control them.

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. Look close. 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. 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. 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 dicamba to the mix.

Other herbicides also can control thistles in pastures – like Redeem, Cimarron, and Curtail. No matter which weed killer you use, though, be sure to read and follow label instructions, and be sure to spray on time.   

Next year, avoid overgrazing your pastures so your grass stands get thicker and compete with any new weeds or thistle seedlings.

Give some thought now to thistle control during October and November. Your pastures can be cleaner next spring.

Alicia Boor is the Agriculture and Natural Resources agent with K-State Research and Extension – Cottonwood District. Contact her by email at aboor@ksu.edu or call 620-793-1910.