Your One Chance to Stop Winter Weeds

No news to anyone here in Texas, summer came in strong and it has stayed a long time.

Normally I’d be telling you that you need to be finishing up applications of pre-emergent weedkillers immediately to prevent germination of cool-season weeds, but the continuation of summer has extended the application time by at least a week.

When you hear that the first significant cold front will push nighttime temperatures into the 60s, and when rain (or irrigation) will accompany the cooler temperatures, apply Dimension, Halts or Balan granules. Hopefully that will be by September 10-15. I get very nervous with applications made after that. If you apply the granules after the weeds have sprouted you’re going to have to live with them.

Annual bluegrass is the small late-winter weed with hundreds of seedheads. Apply pre-emergent weedkiller granules now to prevent germination of its seeds, also rescuegrass and ryegrass. Click image for larger view.

My first tip is that you check with your local independent retail garden center, hardware store or feed store to locate your supply. Many only sell them in the early spring. Some carry them for the “booster shot” application 90 days later in early summer. Still fewer carry them now to prevent winter weeds before they start to germinate.

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Your local independent retailer can order the granules in for you if they’re currently sold out. That’s another reason to buy this weekend.

Pre-emergent weedkillers must be applied before weed seeds germinate. At this time that’s for annual bluegrass (Poa annua, rescuegrass and ryegrass). It should be noted that annual bluegrass may have some slight resistance to pre-emergent products, but application is still worth making.

Important Note: We do not have a post-emergent product that will control existing winter grassy weeds once they start growing. This is your one chance!

These products are safe on any kind of turfgrass, also beneath trees and shrubs.

Pre-emergents should not be applied if you intend to overseed your dormant lawn with ryegrass for green winter turf.

Do not apply pre-emergent granules to new turf until it has been through its first winter.

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If you intend to fertilize your lawn with a high-quality, all-nitrogen lawn food containing upwards of half of the nitrogen in encapsulated or coated timed-release form, make that application first, then water the lawn thoroughly. Wait 24 hours for the grass to dry, then apply the pre-emergent and water moderately to allow the pre-emergent granules to flow over the surface of the soil.

Clockwise from upper left: dandelions, chickweed, henbit and white clover (all broadleafed cool-season weeds). Click image for larger view.

For non-grassy (“broadleafed”) weeds such as clover, henbit, dandelions and chickweed, among many others, the pre-emergent Gallery will prevent seed germination in the same way and on the same time schedule. However, with these weeds you do get a second chance. If you apply Gallery and still miss some of the weeds, broadleafed weedkiller sprays containing 2,4-D will eliminate them while they are growing. It is less expensive than Gallery, so it’s a good option.

Posted by Neil Sperry
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