Herbicides for Winter Weeds in Lawns

R. Keith Collins, Strahan, Ronald E.  |  3/15/2011 11:40:32 PM

Keith Collins is the LSU AgCenter county agent for Richland Parish. This news article will appear in The Richland Beacon News on March 17, 2011.  Author is Dr. Ron Strahan, LSU AgCenter. 

Atrazine liquid:
One of the best winter weed controls is liquid atrazine. It can be used from late March through May for winter weed control. It does a really good job on chickweed, clovers, lawn burweed, dollarweed and works well on annual bluegrass (little grass plant that takes over yards in the winter).

The herbicide usually takes two or more weeks to melt winter weeds away. Rainfall two or three days after application speeds up herbicide activity since the atrazine is mainly taken up through the roots.

Apply on:
St. Augustine grass, centipede grass, zoysia and dormant to semi-dormant bermuda grass. It is also acceptable to use on mixed species lawns.

Rate (4 percent active ingredient homeowner versions): 4.30 ounces to 8.60 ounces of atrazine per gallon of water. One gallon of water should cover 1000 square feet.

Strengths: Good on most winter broadleaves as well as annual bluegrass.

Weaknesses:
Does not work well on wild onion, blue-eyed grass and other lily type weeds. Altrazine is poor to fair on ryegrass. Atrazine does not work well on the pink flowered oxalis. Avoid application around the drip-line of trees and shrubs.

Ferti-lome Weed Free Zone (2,4-D, mecoprop, dicamba, carfentrazone):
Controls several winter broadleaf weeds, including clover, chickweed and bedstraw. Also, this herbicide is good on blue-eyed grass and wild onion. Sometimes follow-up applications are needed two to three weeks after the initial application.

Apply on: All southern turfgrass including bermuda grass, zoysia, carpet grass, St. Augustine grass and centipede grass. Avoid applications or limit spraying to very careful spot treatments when temperatures exceed 90 degrees.

Rate: 1.5 ounces to 2.0 ounces of Weed Free Zone per gallon of water. One gallon of water should cover 1000 square feet.

Strengths: Good on most winter broadleaves and lily/iris type weeds.

Weaknesses: Does not control annual bluegrass or ryegrass. Weak on the pink flowering oxalis.


Ortho Weed B Gon: (2, 4-D, mecoprop, dicamba, carfentrazone):
Controls several winter broadleaf weeds including clover, chickweed and bedstraw. Also, this herbicide is good on blue-eyed grass and wild onion. Sometimes follow-up applications are needed two to three weeks after the initial application. Weed B Gon now contains carfentrazone as does Ferti-lome Weed Free Zone.

Apply on: All southern turfgrass including bermuda grass, zoysia, carpet grass, St. Augustine grass and centipede grass. Avoid applications or limit spraying to very careful spot treatments when temperatures exceed 90 degrees.

Rate: 3.0 ounces of Weed B Gon per 1000 square feet.

Strengths: Good on most winter broadleaves and lily/iris type weeds.

Weaknesses: Does not control annual bluegrass or ryegrass. Weak on the pink flowering oxalis.



Granular (non-fertilizer option)

Green Light Wipe Out Tough Weed Killer for Lawns (penoxsulam)
Green Light Wipe Out (penoxsulam) has activity on certain winter broadleaf weeds like chickweed, dandelion, clover and somewhat inconsistent on dollarweed. Spread this like fertilizer on the lawn when the lawn is wet from dew (early morning) or after irrigation. The granules must stick to the leaves of the weeds for this product to work. This product is very slow acting and requires three to four weeks or more to be effective. A second application can be made in three to four weeks after the first.

Rate:
3.4 pounds of Green Light Wipe Out granules per 1000 square feet.

Apply on: All southern turfgrass including bermuda grass, zoysia, carpet grass, St. Augustine grass and centipede grass. May be applied when temperatures exceed 90 degrees.

Weaknesses: Granules must stick to weed leaves for herbicide to be successful. Need at least 24 hours with no rain. Does not control annual bluegrass or ryegrass. Very slow activity with inconsistent results.


These products or their equivalents are mostly available locally. Please shop at local garden centers and nurseries for your local home and garden needs. For more information call your Extension office at 318-728-3216 or visit us at 702 Madeline Street, Rayville, La. or go to our website at www.lsuagcenter.com/richland.


Author: Dr. Ron Strahan
School of Plant, Environmental and Soil Sciences
http://www.lsuagcenter.com/en/communications/authors/RStrahan.htm







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