Pre-Emergent for Weeds in Floratam Grass

Atrazine

• Herbicides formulated with atrazine may be used on St. Augustine grass cultivars, but should only be applied to Floratam lawns when the temperature is below 85 degrees Fahrenheit. Make no more than two applications per year.
  Water the lawn a week to 10 days after application to help the herbicide penetrate to the weeds' roots. Spray thoroughly to wet the weeds, but not to the point of runoff. Atrazine-based herbicides should not be allowed to contact pond water, as it is highly toxic to aquatic life. It should also not be used on sandy or loamy soils where it can seep into groundwater.

Benefin-Trifluralin

• Benefin-trifluralin pre-emergent herbicides may be used on a wide variety of grasses, including established St. Augustine grass and its cultivars. It may be packaged with a fertilizer to help boost lawn health while providing pre-emergent control of weeds. A maximum of two applications per year are allowed and may be done 10 to 12 weeks apart. The granules should be applied in early spring using a mechanical spreader to ensure even distribution over the lawn. In addition to being extremely toxic to aquatic wildlife, children and pets should not be allowed on the lawn until all dust from the application has settled or, once watered in, the lawn is dry.

Oryzalin

• Also toxic to fish, oryzalin herbicides should not be sprayed where overspray or runoff can impact aquatic wildlife. This herbicide only controls pre-emergent weeds and should be sprayed before weeds germinate. Fill a tank or pump-type sprayer three-fourths full of water and mix 1 to 1.5 ounces of herbicide, agitating the mixture well. Spray the lawn thoroughly, agitating the tank to keep the herbicide well mixed. Wait three months before making repeat applications.

Tips and Caution

• Check the label for both the type of weeds present in your lawn and to make sure Floratam is not expressly excluded from the list of appropriate grass species. Not all herbicides are safe for Floratam grass.
  Set the sprayer nozzle for a coarse, low-pressure spray to minimize the risk of herbicide drifting to and injuring or killing desirable plants. Roll mechanical dry spreaders slowly to keep dust drift to a minimum.
  Avoid getting herbicide sprays on tree roots, and never spray directly on water surfaces.
  Wear protective clothing such as long-sleeved shirts, safety glasses and gloves to minimize the risk of possible skin irritation from directly contacting herbicides.