"Steve Ravet" wrote in message
...
My lawn went from less than 10% St. Augustine to over 80% in just a few
years with only occasional watering and regular mowing. It overcame
everything but crabgrass, which came in a couple years ago when there
was a total ban on watering in Pflugerville. The crabgrass is very
thick, thicker even than the St. Augustine. They've battled each other
to a standstill. Is there something I can use to knock back the
crabgrass and give the St. Augustine a chance to move in? I read about
using pre-emergents but it's too late for that now. Anything else?

You've run into the biggest problem with St. Augustine. The best way to
take care of it is to apply pre-emergence products in Jan-Feb. If we have a
warm winter and the crabgrass doesn't die in the winter (crabgrass is an
annual) you can use round-up and as long as your St. Augustine is dormant
and not green, it won't harm it. You can also hit it with round-up now. It
will kill the surrounding St. Augustine. 1 week later put a plug of St.
Augustine in the middle of the sprayed area.

A product called Image will kill crabgrass in the summer. I've never had
St. Augustine so I don't know how harmful the stuff is to St. Augustine, but
the label says it's OK. It's quite expensive. A small bottle will run you
almost $30 and will only make a few gallons. I would use it in a test area
to see how it affects your grass.

If chemicals don't work, keep the crabgrass mowed short at all times.
Crabgrass grows faster than grass. When you mow it, the crabgrass has to
use energy stored in it's roots to recover. So if you are constantly
keeping it mowed down, it will have a harder time than the St. Augustine
will. Also it has to get taller to put out seed which will cause problems
next year.