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You’ve worked hard on your landscape all summer long and it’s looking great. Don’t let winter weeds interfere with the beauty and function of your turfgrass.


Oklahoma will continue to deal with temperatures in the 90s for a few more weeks, but it’s the time of year when homeowners need to start thinking about treating winter weeds.


Weeds aren’t just a summertime thing. Annual bluegrass, rescuegrass, cheat and downy brome are winter annual grassy weeds. Chickweed and henbit are winter annual broadleaf weeds. It’s a good idea to get a head start on treating them with preemergence herbicides.


For winter annual weed control with herbicides, apply a preemergence herbicide about two weeks prior to germination, which typically is between now and mid-September. Preemergence herbicides are chemicals that control annual grass and broadleaf weeds when applied prior to weed seed germination. They don’t do any good once the weeds are already growing. By the time you see them in your landscape, it’s too late. Early detection is key.


Most of the products available to the homeowner will last from four to six weeks to three to four months, depending on the chemical and weather conditions. In some cases, a split or second application is recommended to provide season-long control.


When it comes to treating weeds, it’s not a one-size-fits-all situation. No single herbicide will kill every type of weed. And not every product available is good for all areas of your landscape and garden. Picking the right product for your specific weed problem is vital, so it’s important to read the label before purchasing.


Preemergence herbicides are applied to the soil, often as dry granules and sometimes as a liquid spray. Tillage prior to application allows better penetration and distribution of the herbicides in the soil. Most products work better when applied to moist soils versus dry soils. All preemergence herbicides must be activated by half an inch to an inch of rainfall or irrigation, or must be mechanically incorporated to be fully effective. Check the weather forecast for possible rainfall in your area to avoid overwatering.


Most preemergence herbicides can safely be applied over the top of many ornamentals, but be sure to apply granular products to dry foliage. Chemicals coming in contact with foliage of desirable plants are likely to cause plant injury.


When we find products we like, it’s easy to stick with what we consider to be a sure thing. However, applying the same herbicide time after time can result in a buildup of weeds resistant to that particular herbicide.


Avoid using preemergence herbicides in areas where you plan to grow plants from seed. Preemergence herbicides can affect many germinating seeds of the plants you want to have in the garden, not just those of weeds. Whatever product you choose to use, read the label to ensure you’re applying the right product.

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