Rushes are good at three things. 1) sucking up water and making sodden ground usable; 2) shelter for sheep, especially lambs; 3) cover for ground-nesting birds.
Management is essential,
eradication is actually not always desirable and in any case is usually a losing battle!
If managed correctly, there will be quite a bit of grazable grass in between the clumps. So you will get some usable grazing and some good shelter, as opposed to a quagmire.
And wildlife too
The best management is topping. If you want some rush cover for shelter and for wildlife, top 1/3 each year, leaving some at different heights in patches. Top once in July after the ground-nesting birds have flown, and again 6-8 weeks later if you can.
If they really get away from you and you need to get back on top of them, the best results are by topping first, then using a weed wiper when the new growth is long enough. The older, hard stems are relatively impermeable to chemicals, hence topping first then treating the softer new growth once it’s long enough to stand proud of the surrounding grass. This way you get little chemical on the plants other than the rushes you are aiming to kill.
:bookmark: rushes are good for you
Bookmarking because I write all this out several times a year...