Lawn Greenup May Not Be Grass

Keith Fontenot  |  4/1/2005 12:53:27 AM

By March, most lawns are beginning to show good spring re-growth. Many lawns have already been mowed two or three times. The problem with some of that re-growth is "all that is green may not be grass." Many weeds will be evident in most lawns coming out of the dormancy period. Mowing the lawn at a good mower height will help control these weed pests. Cutting heights recommended for Louisiana lawns are:

  • Common Bermuda - 1.5 inches
  • Hybrid Bermuda - 1 inch
  • Zoysia - 1-1.5 inches
  • Centipede/Carpet - 1 inch (2" in shade)
  • St Augustine - 2.5 inches (3" in shade)

These cutting heights will help to control weeds, encourage a healthy, thick, turf, and also stop scalping of the grass roots, which can be injurious in dry weather. In a severe period of dry weather, even higher cutting heights are recommended.

For some lawn weeds, herbicide control is the best answer in combination with good cutting height and a balanced fertilization program. One of the primary factors in controlling these weeds is proper identification of the weed.

Probably the lawn weed that has given more problems to homeowners in the parish the last few years is called lawn stickerweed, stickers, peqants and many other names. This problem weed is known as lawn burweed, spurweed or sandbur. This weed seed germinates in the fall and remains small through the winter and early spring. You may identify it by the small, fine, almost parsley-like looking leaves. Many people say it looks like a tiny ragweed seedling. The leaves are opposite, hairy and have many lobes.

As temperatures rise in the spring, this weed really takes of. The painful sticker we feel when we walk on them is formed at the junction of the leaf to the stem of the plant, the leaf axil. This happens after flowering, which usually occurs early in April. As the weed grows, it may reach a height of 3 to 4 inches and a diameter of 6 inches.

The best time to control lawn burweed is during the winter; however, we can control it in March. The key to control is to stop it before the plant flowers and the burs or stickers are formed. Even if we control it after the sticker is formed, the sticker will still be in the lawn, just waiting for a bare foot.

On Bermudagrass that is not overseeded with a cool season turf, Atrazine, Simazine and Sencor can be used. Other more common herbicide options include: 2,4-D, Banvel and 2-way and 3-way mixtures of 2,4-D such as Tri-Mec, and Weed-B-Gone, which can be used on Bermudagrass overseeded with a cool season grass. These 3-way mixtures are effective, although more than one application may be needed.

These products should be applied according to label directions and consideration given to daytime temperatures when applying. With all 2,4-D products, and herbicides in general, be cautious of other non-target plants, trees and gardens to prevent herbicide drift or accidental misapplications. Warm, sunny day applications when temps are 55 or higher will give best results. The lawn burweed will also begin to die back on its own when daytime temperatures begin to reach the 90 degree range. Remember to control this problem before the burr or sticker is formed. After they formed, they will remain in the lawn even if the weed is controlled. The only choice you have at that point is to wear shoes and allow time for the stickers to decompose.

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