Fusilade II Herbicide is the best chemical control option. Although it's not labeled to kill St. Augustine grass, it's also not labeled to treat St. Augustine.

Is Fusilade safe on St Augustine?

Answer: Fusilade II can only be used to remove bermuda grass from Tall Fescue and ZoysiaG rass when used at reduced rates but it is not labeled for use on St Augustine grass so we cannot recommend it for this use. We are not aware of a product that is labeled to remove Bermuda grass from St Augustine.

What herbicide kills St Augustine grass?

Ortho® Weed B Gon® Weed Killer for St. Augustinegrass Ready-To-Spray is guaranteed to kill weeds down to their roots. The easy grip control is perfect for broadcast applications so you can kill over 250+ weeds without damaging your lawn. * Use Ortho® No.