A preemergence herbicide stops turfgrass weed growth before it begins by preventing the germination of weed seeds. Understand the purposes of both selective and nonselective herbicides and understand the ways in which weed control efforts are impacted by initial application timing, watering, and reapplying.
It’s hard to believe that we’re already halfway through January! Before we know it, the days will be hot, and we’ll be back in the routine of regular afternoon showers. While there are indeed things to look forward to with spring and summer approaching, these seasons bring with them unwelcome and unruly weed growth in turfgrass.
This means that now is the time to make a plan of action for weed control. There are ordinary weed control methods, like mowing and pulling by hand, but there’s another method worth considering: the application of preemergence herbicides.
In this article, we’ll cover the two main types of preemergence herbicides, application timelines to adhere to, and important steps to take to ensure effective weed control.
Preemergence Herbicides: What Are They?
Many of us are accustomed to tackling weeds as they show up, but preemergence herbicides make life much easier by stopping weeds before they grow. These chemicals work by preventing the weed seeds themselves from germinating, thus preventing the growth of weeds. Because of the way these herbicides function, they must be applied to turfgrass before the germination of weed seeds. Preemergence herbicides are typically used to work against annual grasses and annual broadleaf weeds.
Select the Appropriate Herbicide
Not all preemergence herbicides are the same, and you must understand the difference between your options to choose the best one for the weed situation you face.
If weeds are invading your turfgrass, a selective herbicide is likely the best option for you. These preemergence herbicides will cause no harm to your turfgrass but will work to prevent weeds from germinating and growing. They can be applied directly to patches of turfgrass with no effect on the grass itself. Selective herbicides are specific to different species of turfgrass, though, so be careful to choose the right herbicide for your lawn.
Nonselective herbicides, on the other hand, do not discriminate. Regardless of species, these herbicides will prevent any plant seeds from germinating, effectively killing all plants they encounter. While you should be careful in applying a nonselective herbicide, it could be the perfect option for you if you want an area to be totally free of vegetation.
Get the Timing Right
If applied too late in the weed life cycle, preemergence herbicides will have missed their window of effectiveness. Differing temperatures across Florida mean slightly different timelines for each part of the state. Still, in general, herbicide application should take place by the time or before daytime temperatures reach 65℉-70℉ for four consecutive days.
In South Florida, plan for herbicide application by February 1st. In Central Florida, by February 15th. And in North Florida, by March 1st.
Make it Count: Water and Reapply
After putting in the effort to select, purchase, and apply a preemergence herbicide, the last thing you want is to skip the final steps ensuring its activation. These two things are crucial, whether you’ve chosen a selective or nonselective herbicide.
First, you must water the turfgrass either immediately before or immediately after applying the preemergence herbicide. Water is what activates the herbicide; it will do nothing if it remains dry.
Second, expect to reapply the herbicide every 6-9 weeks. After the first application, the majority of preemergence herbicides will work for 6-12 weeks. For season-long weed control, read up on the specific product you have selected and plan your reapplication ahead of time.