Removing St Augustine from zoysia grass lawn

Q: My lawn is Emerald zoysia but it has some type of second grass growing in it. It looks like St Augustine (or centipede), but I am not sure. I have tried everything to kill the second grass, but I am not winning the battle. Can you identify the weed/grass?

A: You were smart to include a picture of the seedheads. This is the only way I can be sure what grass we’re talking about. If it is St Augustine, as it appears to be, it will be hard to get it out of the zoysia lawn.

It’s too complicated to use something to spray it out. Herbicides are only slightly selective against St Augustine. If you have a reel lawnmower, you could mow the lawn really low for a summer and kill most St Augustine grass that way. I would not try it with a rotary mower.

In my experience, Emerald zoysia will choke out St Augustine after several years.

Maybe the best thing to do is hire some kids to go through the lawn once a week and pull the St Augustine runners of the ground.

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