Augustine invading Empire Zoysia

rdebay – posted 10 June 2007 20:53

My Empire Zoysia lawn is being invaded by St Augustine. Is there anything I can use to kill off the Augustine without hurting the Zoysia?

TexanOne – posted 11 June 2007 03:16

You can try Confront herbicide. Success will vary depending on what variety the St Augustine is. Texas Common St Augustine seems more resistant to the effects of Confront than other commercial varieties.

http://www.dowagro.com/turf/prod/confront.htm

rdebay – posted 13 June 2007 22:36

What do you think of quinclorac (Drive)? The product docs warn about use on St Augustine.

TexanOne – posted 14 June 2007 02:38

Drive 75DF also works and I have used it, but it does not give 100% kill of the St Augustine. The only problem with Drive is, it also damages Zoysia, but to a lesser extent than St Augustine or Bermudagrass. That may sound ok until you realize St Augustine and Bermudagrass recover quicker from the injury than the Zoysia does – leaving you essentially right back where you started.

After many years of trying just about every known herbicide to get rid of St Augustine in Zoysia and being unsuccessful, I now have a predominately St Augustine turfgrass with some Zenith Zoysia mixed in (it was seeded with Zenith in 1999).

Since hindsight is always 20/20, I would have made a different attempt at ridding my yard of St Augustine with spot treatments using glyphosate (Roundup) and just accepting some collateral loss of the Zoysia where the St Augustine was sprayed. I know this sounds radical and some may disagree with this approach, but I will assure you St Augustine is much more vigorous than Zoysia and radical procedures are needed to keep your Zoysia intact.

If the St Augustine infestation is small, you can also try hand-pulling all the St Augustine stolons you find, and glyphosate what you cannot pull out. Yes, you will also lose some Zoysia in the treatments, but unless you aggressively attack the St Augustine, you will have St Augustine lawn in no time – whether you wanted it or not.

Another tip: mow the Zoysia high – at least 3”. Zoysia does have a fighting chance against St Augustine when cut high because of Zoysia’s thick sod.