I try to push back the field edges after each hay cutting. If I didn't there would soon be about a 1/2 acre area in the middle that the hay cutters would cut. One field got so bad we had to bring in a dozer to push back the brush. If we catch a dry winter I do as much as I can to open up any latent grass next spring to sunlight. Give the grass a headstart and it stands a good chance of shading out the undesirable stuff.