It’s time to control your summer weeds! Using a preemergence herbicide BEFORE weeds germinate is a proactive way to treat those pesky summer weeds. Preemergence herbicides are usually applied in a granular form and then watered in. It is important to water them according to label instructions. The herbicide creates a layer in the lawn or landscape environment that stops weeds from germinating.

Do They Work on All Weeds?

Preemergence herbicides, may not work on every weed in the lawn or landscape. Some are better at controlling grasses, while others are better at controlling broadleaf weeds or sedges. Very few, if any product will control all three. Common options for professional landscapers to control grasses and some broadleaf weeds include products with the active ingredients pendimethalin (Pre-m, Pendulum), prodiamine (Barricade), and dithiopyr (Dimension). To control broadleaves, look to atrazine and isoxaben (Gallery). Newer products such as Indaziflam (Specticle) are more expensive, but use less product and have a long list of stubborn weeds they control.

Timing

Timing is important for preemergence herbicides because they have to be down prior to the weed germinating. In North Florida, UF recommends to have product down by March 1st. The March 1st date will help control summer annual weeds, such as crabgrass, chamberbitter (pictured), and doveweed. To control winter annual weeds such as old world diamond flower and chickweed, aim to have the application down by October 15th.

To learn more about preemergence herbicides then visit UF’s publication, Weed Management Guide for Florida Lawns at http://edis.ifas.ufl.edu/ep141. If you are a professional landscaper and need more information about herbicide selection, download a free copy of the 2012 Pest Control Guide for Turfgrass Managers at http://turf.ufl.edu/pdf/2012_UF_Pest_Control_Guide.pdf.

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