James Bond wrote:
Hello, I am wondering if Round Up or other similar non selective herbicides
will kill St. Augustine and/or Centipede grasses when they are in dormance
during the winter. To extend the question, how do these herbicides work
exactly? If they are only absoarbed via the leaves, then it seems that
maybe the dormant grass leaves would not absoarb the herbicide. Any
insight into this is appreciated. Thank you.

JB

Roundup type herbicides are actually variations on the natural growth
hormones, and work by tricking the plants into overextending themselves.
AFAIK, they are taken up through roots as well as leaves. Being
hormones, they don't last long when the plants die, which is the reason
you can replant or reseed with no ill effects about two weeks after the
weeds have died.

So the question is whether a dormant plant will take up the hormone,
start to grow and die. I suspect not, but that's not a good enough
answer for you. I'm sure another poster will tell you what you want to know.