It is time to treat for winter weeds

Monday, September 28, 2015

With the cooler temperature in Oklahoma, many people are ready to put out their hay bales, scarecrows and pumpkins to decorate for the fall season. While thinking about the decorations, it also is a great time to think about fall and winter landscaping needs.

Weeds interfere with the beauty of your landscape and the function of turfgrass areas, said David Hillock, Oklahoma State University Cooperative Extension consumer horticulturist.

“If winter annual weeds, such as henbit, rescuegrass, cheat and annual bluegrass, have been a problem in the past, homeowners will definitely want to apply a preemergence herbicide as soon as possible,” Hillock said. “Many of our winter annual weeds germinate in the fall or early winter and survive as very young plants until late winter or early spring when conditions are more favorable for growth. Waiting until you notice them is too late. Annual weeds complete their life cycle in one growing season and come back each year from seed.”

The key to effective control is timing. Preemergence herbicides must be applied well in advance of the expected germination time of the weeds to be controlled. In addition, the products must be watered in to activate them.

Hillock said gardeners will need at least a half-inch of water, either through rainfall, or irrigation if no precipitation is expected within a couple days, after application. In some cases, the product needs to be incorporated into the upper surface of soil.

“There are several products available in the garden centers that will effectively control germination of most winter annual weeds. Some are labeled just for turf areas and some are labeled for both turf and ornamental areas,” he said.

Two products, one containing a combination of benefin/oryzalin, and the other bensulide, are labeled for use in lawn and ornamental areas. Another product available that contains trifluralin can be used in ornamental and vegetable beds.

Be sure to read and follow the label directions for best results and to avoid damaging any desirable plants.

“Now is a great time to get outside and start on your prewinter landscaping. The things you take care of now will give you a great head start when gardening activities pick back up in the spring,” Hillock said.