spray is best , I have just sprayed my paddocks and needed to keep horses off them for 7 days , spraying them will kill them so they wont come back wheras if you cut them they will continue to grow.
Speak to your local farmer
Sorry its a brand of weedkiller. When I bought my land three years ago I had a dense covering of nettles covering an access route. They hadn't been tended before and now they are gone completely and it was SBK that I used.