Atrazine is an herbicide that offers broad-spectrum weed control and is safe to use on crops, according to botanists at Purdue University. Used primarily on cornfields, atrazine is also effective against broad-leafed weeds in some types of St. Augustine turf lawns. Although the manufacturers suggest that atrazine herbicides can be used for both pre-emergent and post-emergent weeds, scientists at Purdue University recommend you use it after the weeds have appeared. They claim you will use less of the product because foliar spraying is more effective than soil applications.
Plan to spray the weeds with atrazine only when there is no rain in the forecast the day of application and for three days after.
Mix the atrazine herbicide with water, according to the rate suggested on the label, in a compressed-air or hose-end sprayer.
Spray the area in an even arc, from side to side as you walk backward, thoroughly soaking the leaves. Turn off the sprayer if you cross waterways.
Keep people and pets off the area until the atrazine has dried.