Couch grass in old raspberry row

Years ago, I read that when the canes are dormant, you can apply a weedkiller, but I never really had the nerve to do this!

The main problem is that couch goes down as far as the furthest rasps roots, and gets totally entangled. We've decided to just leave it all there this year, as rasps are pretty damn good at getting going - couch grass or not!
(We do mow/strim the couch each week though.)

We also regularly feed the rasps (to counteract the greedy grasses), and the canes really do get going well with a dose of liquid manure.

I have got it around my gooseberries and this year I am going to use that new paint on roundup and hopefully it will be goodbye couch.(after they have fruited tho)