Posted: 15/02/2016 at 14:31
Glyphosate kills couch very well and couch can easily be completely and permanently killed when it is open to spraying. It is much more of a challenge when growing intermingled with plants but under the canopy of shrubs, for example, is easy to selectively spray.
There are two secrets.
1.The couch needs to have had chance to make a good top of green leaves to drink up the weedkiller
2. The couch needs to be intact as a plant. Lots of little pieces chopped up by cultivation are not sufficiently exposed on account of erratic regeneration from each 'root' (rhizome).