Herbicides for Weeds in Lawns: The Most Common

There are many choices of herbicides for weeds in lawns. First, you need to determine what kind of weeds you have. Then, you need to be aware of how the herbicide works before buying the right product for your particular situation.

These are the most common preemergents and postemergents on the market...

PreEmergent Herbicides

Atrazine controls several annual grasses and broad-leaved weeds, but only in lawns of centipede grass, St. Augustine grass, or zoysia grass. It does not do damage to woody ornamental plants.

Benefin will control annual grasses in many lawns, but is not safe for bent-grasses. It prevents all seeds from germinating for about eight weeks.

Bensulide is a control for annual grasses and certain broad-leaved weeds. Seeds will not grow for four months after an application. It is safe for use on bent-grass lawns.

DCPA is especially deadly to germinating seeds of certain broad-leaved weeds such as chickweed and purslane. This is damaging to new lawns, and reseeding cannot be done for 11 to 13 weeks. It is not recommended for bent-grass.

Oxadiazon controls annual grasses. Do not use on fine fescue or bent-grass. Do not reseed for at least 4 months.

Pendimethalin is used for many annual grasses and some broad-leaved weeds. It is not recommended for bent-grass.

Siduron works well on weedy grasses, including crabgrass, foxtail, and barnyard grass. It has the unique trait of not interfering with the germination of cool season grasses such as Kentucky bluegrass.

Post Emergent Herbicides

CAMA, MAMA, MSMA are a group of chemicals called organic arsenicals. They control grassy weeds like crabgrass and foxtail. They are effective against some nutsedges. More than one application is required.

Cacadylic Acid kills only on contact. Several treatments are needed to kill hardy perennials. This chemical works by killing all green growing leaf tissue. It will not move through a plant to the root system. It is also sometimes used to clear weeds from an area prior to planting a lawn.

Dalapon is used against all grasses. Spot treatment is the most efficient and effective method of application. Residual toxicity can last for four months.

Dicamba (Dimethylamine Salt of Dicamba (3,6-dichloro-o-anisic acid) is frequently used against clover, chickweed, and knotweed. Dicamba affects plant hormones. It is absorbed through the roots and leaves. Do not use products containing this ingredient around trees and shrubs, which also may absorb it through their roots. Dicamba is used in mixtures with other herbicides such as 2,4-D and MCPP. It stays active in the soil.

Glyphosphate is nonselective, which means it kills all plants. It is also systemic, meaning the plant absorbs it like a poison It works slowly, as it takes some time for the plant to absorb and process the poison. The plant is killed completely-from leaf to root. Glyphosphate is an effective chemical for most perennial grassy weeds. Roundup is the most familiar brand name product.

MCPP (mecoprop: 2-methyl-4-chlorophenozypropionic acid). This is similar to 2,4-D but is safer to use on new lawns or sensitive grasses such as bent grass or St. Augustine grass.

2,4-D (Dimethylamine Salt of 2, 4-Dichlorophenoxyacetic acid) is a growth regulating hormone compound. It is not a persistent pesticide in the soil. In somewhat warm soil, its half life is 2 weeks or less. 2,4-D is not a persistent pesticide in water. There is 90% disappearance in less than 2 weeks. It decomposes in sunlight.

2,4-DP is very similar to 2,4-D. It controls hard to kill broad leaved weeds like oxalis and mugwort.

Note: New herbicides for weeds in lawns are constantly being developed. Check with your local garden center for the latest products. Make sure you read the label carefully.

If you get tired of battling weeds or don’t want to be exposed to pesticides, have a local lawn treatment company do it. I like how you can sign up online for a free estimate.

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