||02-19-2012 07:06 PM
Feeding on a calculated and regular basis will help as much or more than application of an herbicide at this point. It is a strength in numbers game when it comes to turf and the upright grasses will eventually crowd the broadleaf weeds. And mow the zoysia as tall as possible and that makes sense. This will tend to block light from the weeds.
Even if not designed to kill plants that are not broadleaf, any herbicide can stress turf somewhat. You should be alright applying Weed-B-Gone or similar product. I would error on the side of caution, invest in a gallon tank sprayer (mark it for use with weed killer only) and apply it that way rather than with a hose end sprayer unless the weeds are so widespread this makes no sense. If they are extremely widespread I would use a granular Weed-N-Feed product formulated for broadleaf weeds.