Question
I overseeded my st. augustine lawn on Saturday with perennial rye seed. Heavy rains came on Monday and temporarily flooded my lawn and my neighbors.  I assume that some of the seed floated into his lawn since he is downstream from me as far as drainage goes. I expect that my neighbor will now have rye popping up any day now in his lawn. How can I get rid of the rye grass?  I live in south Louisiana outside of New Orleans.

Also, I've read conflicting stories that perennial rye grass returns each year. On the other hand I've read that in southern climates, I guess like south Louisiana that it won't.  what do you think?

Answer
Tim:

Perennial rye should die out when spring temperatures rise above 85 - 90 degrees or so.  But it may survive and return.  Just keep mowing and do not let it seed.

If your St. Augustine actually goes dormant, you may apply Roundup or like to it during its growing season, which is  the winter.  If the St. Aug's does not go dormant, you may have to wait until late spring to see it disappear or slow down.

In LA, you may be faced with a zone which will allow the rye to survive and St. Aug's to be growing some all winter.  In dormancy, the St. Aug's will have no green parts to the plant above ground after very cold weather.

Try annual rye next year.  It is easier to manage.

Best wishes.