Question
I have a lot of perennial rye in my zoyziagrass lawn that I would like to kill off during this winter.  Is it safe to use Roundup on completely dormant zoyzia?  My only other choice seems to be to pay a fortune for Certainty.

Answer
Kurt:

I do not know where you are located and can not advise very well.  In the mid-Atlantic states, where zoysia is dormant, Roundup may work well when temperatures are above 50 deg F and below 80 deg F.  Apply to rye where it grows only and in light dosage, 1 ounce per gallon, not 3 oz/gal.

A good URL for commercial herbicide application practices from University of Georgia is:

http://commodities.caes.uga.edu/turfgrass/georgiaturf/WeedMngt/weedcontrol/sodwe...

These are commercial products.  You may have to search for them at retail outlets.

Kansas State University reports that use of Roundup is permitted in full dormancy.  Pre-emergents are recommended for winter weed control in fall and for summer weeds in spring.

Best wishes.