Man the pre-mixed stuff from the stores are a big hit and miss Clethodim

Joe, have you actually used that in St. Augustine grass?

You could use Celsius WG, although you must be careful with it.

The weed may be lespedeza (Japanese clover). It's a real pain. Is this it?

Robert, I'll take a look when I get home. My guess; that's not it. The leaves are more rounded, versus those are somewhat elongated. I'll post a pic.

Products with atrazine are what you need in St Augustine. It might be too hot to apply now. Read the directions carefully, twice...three times - to ensure you apply it correctly. Remember herbicides are a foliar mist, not a soil drench.

Weed - b - Gon is not for use on St Augustine. Read the labels.

Jojnb, it could be black medic

dchall - this is what I used. I don't see Atrazine in the contents label. I applied it in the evening when it was cooler. Says right on the label "for St. Augustine lawns" . And I included a pic of the weeds.

Listen to dc, that's the same stuff as the regular weed b gone, just severely diluted. 2, 4-D will damage/kill your lawn be very cautious if your lawn is stressed and/or high temps.

It's pretty much 85 or higher every day, I don't think atrazine is the way to go for now.

I may try again when it cools down. But it sounds like the reward isn't worth the risk, in this case. I don't have a lot of weeds. And generally our lawn looks pretty good. What is the explanation for the challenge with St. Augustine grass, and weeds? Is it really a weed itself, as some people say?

I'm probably going to give pre-emergent a try in the fall/winter.

John, if you're willing to spend a little upfront, Celsius WG will probably do what you want. Others have mentioned bonide sedge ender. In both cases there are some restrictions for st Augustine grass. I just switched to st. Augustine grass recently and now I use Celsius after help on forums. Google those products on this and other forums, or PM me and I could give you links.

Weed b gon takes a few weeks to work