Pull them out by hand.
I have equisetum that is literally everywhere but I do not want to eradicate the plant and enjoy that it is doing so well though it seems to dominate certain areas. It generally grows near the surface and if your soil is moist you can easily just pull up the stalks. do not compose.

If you want to keep some growing try containing it in an enclosure that is buried into the ground. You may also wish to donate some to a local school for study of this very ancient plant!

I think I've heard that pulling it accelerates its spread. I also think I've heard that it grows less well in more fertile soil. Google about it, or use the search function in the whole GW site; something will come up.

To clarify.
When I pull up the plant it is not breaking off the visible stem but pulling up the visible stem plus that part of the underground stem that the visible stem is coming from.
This effectively stops any further growth at that point because it is gone! The areas in my yard that I have not done any pulling are heavily grown in with the horse-tail.
the areas that I have pulled up the stems are cleared but that does not mean that continued growth into the area will not occur.
Give it a try and see how you feel about it. Using herbicides is really not the way to go. I avoid them except for weeds in the cracks of sidewalks.

my garden club does the annual plantings around our local library in MI-and it was full of horsetail. about 2 years ago after googling many, mnay web sites, I think it was Purdue U that told me they did an experiment on several plots of horsetail. Hand pulling it made no difference in the following year, it was just as thick as the uncontrolled test plot. Roots extend over 4 feet down. The only thing that worked for them and for us-was Poison Ivy strength Round-up. Every week, I spray a little bit on JUST the feathery plant that showed its head out of the soil. a time consuming and back-bending job, probably used about 3 qt bottles the first summer. But now we have very few plants that pop up. The birds must have dropped some poison ivy seeds, because I have seen a few of them, & they are getting sprayed too. Being very careful to hit only the horsetail and poison ivy with the spray, most people do not know those problem weeds are in the full, colorful beds

chris_ml,

Your suggestion conforms with many other suggestions I have received. Do you remember the specific brand of roundup that was used. Also what kind of health safety precautions I must take to apply this herbicide ?

-Thanks,
-lg