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You would like to convert all or part of your yard to a low maintenance, low-water use desert landscape. Removing turf other than bermuda grass is simply a matter of cutting and rolling it up. But your yard is bermuda grass. What do you do?
Bermuda grass is a very aggressive warm season plant. Both common and hybrid bermuda can reproduce by stolons (above ground runners), rhizomes (underground runners) or seed. The only viable way to eradicate this plant is by chemical treatment. The best chemical to use is called glyphosate. It is marketed under the names of Roundup (Monsanto), Doomsday (General Control) and Kleenup (Ortho Products). Glyphosate is a foliar herbicide that kills or damages plants that it contacts. It enters through the leaves and moves through the plant into the roots. This will take about ten days. Don't spray desirable plants. Protect them by using shields, a lower sprayer pressure, and a nozzle adjustment for a heavy spray. If you accidentally get some of the glyphosate on a plant, cut off the affected area and wash down the plant with fresh water immediately. Glyphosate does not affect the soil even if you accidentally spray it. Glyphosate disrupts the biochemical process that produces aromatic amino acids. Since only plants have this biochemical pathway, only plants are affected by this chemical. Thus this herbicide is less toxic to animals than table salt.
Do not use soil sterilants
Soil sterilants such as Ureabor, Troix, Pramitol, or Hyvar-X are dangerous and they prevent seeds from germinating (sprouting). Soil sterilants last for several years and they are picked up by the roots of nearby trees and shrubs.
One week prior to applying glyphosate, irrigate the lawn area to get the grass actively growing. The temperatures should be above 70 degrees. Do not exceed the recommended rate on the herbicide label, and apply the herbicide evenly. It is not necessary to saturate the grass with the herbicide. Allow about two weeks for glyphosate to work.
You will probably need to make a second application at the end of the two-week period. Re-irrigate to get the remaining grass to grow actively and then reapply the chemical. Two or three applications are normally required to achieve full control of bermuda grass. If rain is expected within eight hours of application, wait for a dry period because the effectiveness of glyphosate is greatly reduced by rain.
When the grass is brown and dead, apply gravel or decomposed granite ¾ to 1-½ inches deep. If the grade is higher than the surrounding area, you will have to lower the grade by either "scalping" the lawn area using a mower set low or using a power rake (verticutter). Power rakes are available at rental service stores. Remove as much of the grass as possible. Make the rough grade about two inches lower than the surrounding area to prevent granite or gravel from getting on walks or patios.
To prevent weed seeds in the soil from germinating later and becoming a nuisance, apply a pre-emergence herbicide before putting down the decomposed granite or gravel. Dacthal and Surflan are pre-emergence herbicides. Dacthal is often expressed on labels as DCPA. It is marketed as Dacthal (Diamond Shamrock Co.), Pre-emergence #1 (General Control) and other product names. Surflan is marketed as Surflan (Elanco), Weed Blocker (Monterrey Chemical) and Pre-emergence #2 (General Control). This type of herbicide prevents weeds from germinating and getting established. They are safe if used according to the label instructions, at the proper rate, and at the right time of year. This herbicide needs to be watered in with one half inch of water following application.
Since pre-emergence chemicals will not affect weeds already established, they are normally applied soon after the lawn has been killed and before the rainy season in summer and winter. Pre-emergence weed killers are best applied in November and June, just prior to the rainy season. If however, you decide to convert your lawn at another time of the year, treat the area with the pre-emergence at that time and again in November and June.
Do not use plastic ground cover
Another option is to lay down jute or landscape fabric to control weed growth before installing the gravel or decomposed granite. The use of plastic sheeting is not recommended. Plastic interferes with rainfall and irrigation and prevents chemicals from moving through the soil.
Chemical Control of Weeds
Remember glyphosate works through the leaves of plants, is not absorbed by plant roots, and is not active or long-lived (persistent) in the soil. You can safely plant a tree, shrub, ground cover or flowers in an area where glyphosate was used without any serious plant injury.
The pre-emergent herbicides, Dacthal and Surflan, are both similar in action and both give good control of weed seeds. They will not, however, affect any weed that is already growing. In this situation a "spot" treatment of glyphosate is effective. Hand weeding of annual and perennial weeds is often a practical solution, especially where there are few weeds in a small area.
Do not apply the pre-emergence herbicide to any area you plan to seed to desert flowers, native grasses, etc. This chemical will prevent seed germination. However, you can safely transplant trees, shrubs, ground cover or bedding plants into an area where the pre-emergent has been used without any serious plant injury.
Do not use galvanized steel sprayers to apply glyphosate. Use only plastic or stainless steel sprayers with glyphosate. Read and follow the pesticide label.
Once cubic yard of decomposed granite will cover approximately 150 square feet at ¾ to 1-½" deep.
Roundup Concentrate is diluted at a rate of 6 tablespoons (3 ounces) per gallon of water.
Roundup Lawn and Garden and Doomsday are already mixed and should not be diluted. Add one-half teaspoon of dish soap to act as a "sticker" to all solutions.
Trade names used in this publication are for identification only and do not imply endorsement of products named or criticism of similar products not mentioned.
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