Best Management Practices:
Johnsongrass is considered one of the worst weeds in the United States. Controlling johnsongrass is no easy chore. One has to be persistent and somewhat patient but it can be accomplished. Unfortunately, pre-emergent herbicides alone will not control this perennial weed. Remember, this plant comes back from its roots each year, so it will take both pre-emergent and post-emergent herbicides to take out johnsongrass from your lawn. Pre-emergent herbicides kill germinating seeds while post-emergent herbicides only control weeds that are already actively growing.
Grass Getter and Certainty are labeled as post-emergent products to control johnsongrass. They work very well if used in accordance with the Product Labels. It will normally take at least two applications 10 to 14 days apart to obtain good control. Also, the weed needs to be actively growing (May to August)—some experts claim late summer and fall applications work even better than spring applications with this weed. CAUTION: Make certain the product you select can only be in the turf grass you have without harming it.
Unfortunately there are no post-emergent herbicides that are labeled for controlling johnsongrass in St. Augustinegrass. The ones that will control it can cause a tremendous amount of damage to your St. Augustinegrass. The only solution is to do one or a combination of the following: dig out the johnsongrass by hand and use pre-emergent herbicides like XL- 2G to kill out germinating seeds.
Best Management Practices courtesy of:
Bes-Tex Supply, LLC P.O. Box 664 San Angelo, Texas 76902 Ph. 325-653-1300