Hmm. I posted a reply to George and it appears it did not come through. The mysteries of the internet.
Bindweed I know quite well, as well as glyphosate. Sadly, and innocently I assure you, when I first moved up here 20 years or so ago I was a totally novice gardener and thought that this horrible bindweed was a lovely flowering native vine. I introduced it to my yard, if you can believe it!!! It didn't take me long to learn how very, very wrong I was.
I understand the pain of the woman attached to her tool. My nemesis is english ivy. Well, also the himalayan blackberry and english holly. All of these are extremely invasive in this climate, not giving another thought to our very wet winters which scare other plants away. Our property was totally overgrown with these three when we moved in 5 years ago. I have used the paintbrush technique to great effect. Of course, these are not grasses with their many blades of leaves.
I wonder if one could expose the roots of a portion of couch grass, paint the glyphosate onto the roots, and thereby kill a large portion of the plant. Painstaking, but it might work.