Hi, Stringfellow. We had varying success with horsetail. It’s a prehistoric plant made up of almost total silica and hugely deep-rooted. It’s a herb used for hair rinses, strengthening nails and even an early non-stick treatment for scrubbing pans. I think it has been used for toothbrushes, too.
It’s silica content makes it difficult to kill with chemicals. And it is very brittle. If you can bruise it without snapping it glysophate has some effect. We used to keep it under control by gently lifting the plant without snapping it and trying to pull up as much root as possible. Densely packed ground cover planting did seem to put it off a bit, too.
Good luck.
