Advice on how to prevent, control lawn weeds

By Delta George

K-State Research and

Extension

Bourbon County Extension Agent

Agriculture and 4-H

Many homeowners would say that their top lawn concern is weeds. When developing a lawn weed control program, one should know the kind of grass and total square foot of lawn; identify the problem weed or weeds; determine why the weed invaded the lawn and correct the practices that caused the invasion.

Turf weeds can be broken into five classes; this class determines the best method of control. They are as follows: annual grasses, annual broadleaf weeds, perennial grasses, perennial broadleaf weeds, and miscellaneous weeds.

Annuals will germinate, grow, and produce seeds every year, while perennials will last for more than one growing season due to their root growth, even though the top growth may die each year.

Annual weeds may be further classified as winter or summer. Winter annuals germinate in the fall and die in late spring, while summer annuals germinate in the spring and die the fall.

Perennial weeds are broken down into warm-season and cool-season, depending on when they are actively growing and when control measures should be applied.

There are several reasons why weeds invade lawns. Improper mowing, watering, and fertilizing can be causes, along with insect or disease injury, compacted soils, and excessive wear. Other causes may be the grass variety planted, environmental stress, or excessive thatch.

If chemical control is needed, a herbicide must be selected that is effective for the weeds while being safe for the grass. Always read and follow label directions exactly.

There are basically two types of chemical weed controls, the difference being when they are applied. Preemergence herbicides are applied to the soil before the weeds germinate. Preemergence control is used to prevent annual grasses, but they will also control some annual broadleaf weeds from seed. The time to apply depends on the weeds to be controlled and when they germinate.

Annual weeds controlled by preemergence chemicals include chickweed, crabgrass, and henbit. Chickweed and henbit are both winter broadleaf weeds, so control in best in the fall; crabgrass is a summer annual grass that should be controlled in the spring. In fact, now is the time to apply preemergence herbicides to control crabgrass.

Postemergence herbicides are applied after germination when the plants have emerged from the soil. They are primarily used for broadleaf weed and perennial grass control, but may be used on annual grassy weeds. Postemergence weed control is most effective when the weeds are young and actively growing.

Broadleaf weeds controlled with Postemergence applications are dandelions, wild garlic, wild onion, and plantation.

More information on controlling weeds in home lawns or maintaining a healthy, vigorous lawn can be obtained through the Bourbon County Extension Office.

Editor's Note: Delta George is a K-State Research and Extension agriculture and 4-H extension agent assigned to Bourbon County. She may be reached at (620) 223-3720.敥