Killing the bad grass. (Huh!?)
As pointed out to me by achnatherum, I've got some rogue grass in my clump of miscanthus 'Cosmopolitan'. Whether it's some of the Cosmo reverting back to the species, or some seeds that aren't variegated that have sprouted, I'd like to get rid of it.
I was thinking of bending the rogue grass down to the ground and spraying it with Roundup, being careful not to get any on the desirable grass. Will that do any harm to the grass in the clump I want to keep?