Yes, Sulfentrazone 4SC Select Herbicide can be applied to St. Augustine however per the product label, "St. Augustine grass that has been stress-weakened can experience temporary leaf surface discoloration (removed upon mowing) upon application of Sulfentrazone 4SC Select.
The application rate is 8 - 12 oz. per acre with a minimum of 10 gallons of water. Sulfentrazone 4SC Select is mixed at the rate of 0.18-0.28 oz. per 1000 square feet. This is equivalent to 1-1.6 teaspoons. This will mix in approximately 1-2 gallons of water for spot treating.
Chemicals, certain cultural practices, disease, mechanical exposure and cultivation and weather can all be causes of stress-weakened turf."
Answer last updated on: 10/10/2022