songbird wrote:
glyphosate will work on horsetail eventually.
it helps a lot to stomp on it and using a
good wetting agent to spray. i have wanted to
spray every time i see horsetail anywhere on
the property, but the bad result is that it
opens up the ground for other invasives and so
it seems like it just replaces one problem with
a half dozen others. not counting the trouble
of erosion if it is along the ditch.

My experience has been that spot spraying of weed-b-gon kills horsetail better
than glyphosate.