In message ,
CWatters writes


We had bamboo at our last house. Stuff spread like crazy. I hit some of it
with weed killer on the basis that I didn't mind if I killed the lot. The
bits I sprayed went a bit yellow for a while and sent up more. I'll never
plant it in my garden.


It depends on the type of Bamboo, some are invasive, so aren't.

Re the OP, my thought is left untrimmed, with a larger leaf area it will
take up more of the herbicide.
--
Chris French