Ask The County Agent: Applying a weed-control, pre-emergent on your lawn

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By Stephanie Ray Butcher, County Extension Coordinator

QUESTION:  When should I apply a pre-emergent to control weeds in my lawn?

AGENT: Take care of those warm season annual weeds now by applying a pre-emergent.

Pre-emergence herbicides are applied to lawns prior to weed seed germination. This group of herbicides controls weeds during the weed seed germination process but does not actually prevent weed seed germination. When you see weeds in your lawn, it is too late to apply a pre-emergent.

When applied in mid-late February or early March (before soil temperatures reach 55 degrees), pre-emergent products will control many summer annual weeds such as crabgrass, goosegrass and spurge.

Pre-emergence herbicides are only recommended for turfgrasses that have been established for a minimum of one year. Severe injury can result if they are applied after seeding, sprigging or sodding.

Keep in mind that pre-emergence herbicides do not control all weeds that may be present in a lawn. It is unreasonable to expect a 100% weed free lawn, but a pre-emergent will control many of the most common lawn weeds.

If you have a warm season turfgrass like bermudagrass, centipede, zoysiagrass or St. Augustine, then make sure you do not apply any nitrogen along with your pre-emergent at this time. There are products called “weed-and-feed” that include both nitrogen fertilizer and herbicide in one. Do not use these on warm season lawns this time of year. Fertilizers should only be applied to warm season lawns after all danger of frost has passed. Our final frost date in Coweta County is April 15th.

Many pre-emergence herbicides are available in granular formulations. Granules are easier to apply than sprayable formulations. Additionally, granules are not susceptible to spray or vapor drift that can occur with sprayable formulations. These products should be watered in either with rainfall or irrigation.

Atrazine may be applied to centipedegrass and St. Augustine lawns. Trade names for this chemical include Hi-Yield Atrazine 4% and Image for St. Augustine & Centipedegrass 4%. Benefin is a chemical that may be safely applied to bermudagrass, centipedegrass, tall fescue, zoysiagrass, St. Augustine and Kentucky bluegrass. Benefin is sold under the trade names Balan 2.5G, Crabgrass Preventer 2.5G and Crabgrass Preventer 1.72.G. Contact the Coweta County Extension office for a complete list of pre-emergence products.

As with any chemical, read and follow all label directions and make sure that the product you choose is labeled for your particular type of turfgrass.

Trade and brand names are for information only.  UGA Cooperative Extension does not warrant the standard of any products mentioned; neither does it imply approval of any product to the exclusion of others, which may also be suitable.

For more information about lawn weed control, contact UGA Cooperative Extension in Coweta County at 770-254-2620. Ask for the publication, “Weed Control in Home Lawns.”

Photo Credit: Stephanie Butcher, UGA Coweta County Extension

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