Daniel Gill, Merrill, Thomas A. | 3/4/2006 4:44:43 AM
By Dan Gill
LSU AgCenter Horticulturist
Lawn grasses around Louisiana begin to wake up from winter dormancy and turn green in March, so now is a good time to plan your strategy for having an attractive, healthy lawn this summer.
If your lawn has been on the decline, it is best to determine the cause or causes and consider how to put things right before heading into the summer growing season.
There are several common causes of lawn thinning including insect, weed and disease problems, heavy traffic, poor soil fertility, excessive thatch and too much shade. Poor maintenance such as improper mowing and watering also can be factors. One or more of these problems may be plaguing your lawn, and the situation may stretch back to last year or longer.
Don’t be overly concerned about the lush growth of cool-season weeds, which may appear to be taking over your yard now. The unwanted weeds have just been taking advantage of the dormant condition your lawn has been in the past few months and the lack of regular mowing. Most of the weeds growing in your lawn now will disappear during the summer growing season – when we expect our lawns to look their best.
Excessive sponginess in the lawn usually indicates a thatch problem, which may call for topdressing the lawn or dethatching, depending on the depth of thatch. Thatch is the layer of dead material that accumulates in turf between the green blades and the ground. Every lawn has some thatch, and it usually is not a problem. But a heavy layer of thatch, an inch or more thick, encourages insect and disease development and makes the turf more sensitive to wear and drought.
To topdress your lawn, spread one-half inch of sand evenly over the lawn. The topdressing will settle over the thatch, creating a moist, dark environment that encourages natural decay of the thatch. In some heavy thatch situations, dethatching with special equipment may be necessary. Contact local lawn-care services for this job.
Insects and diseases can greatly damage a lawn. One of the more common diseases is brown patch, which strikes during mild weather and is prevalent in the fall. These patches of brown damaged or dead grass are caused by a fungus that thrives in cool, moist weather. This disease can kill the grass, but it is more common for it to weaken the turf – causing the affected areas to green up poorly in the spring and making them more susceptible to weed encroachment.
When dealing with brown patch, do not be concerned with treating old damage. But be aware that brown patch can occur in spring as grass greens up in March, especially on St. Augustine grass. If you see rapidly enlarging brown areas in grass that greened up normally, active brown patch can be treated with a lawn fungicide labeled to control brown patch.
Turning to another potential pest, chinch bugs are not active now, but they could have damaged your lawn last summer. Chinch bugs primarily are a problem from June through October, and if areas of your lawn died during that time, the likely cause was chinch bugs. Evaluate the lawn in late April or early May to see if those areas green up. Unfortunately, these insects often kill the grass outright, and you most likely will need to replace the turf.
Lawns that have been damaged by wear and tear from dogs, children or foot traffic can be helped with extra care. In early April, use a garden fork to loosen the compacted soil in the bare areas, fertilize the damaged areas and the rest of your lawn and water the lawn regularly to encourage growth. Keep traffic to a minimum in any damaged areas until the turf has recovered. If a damaged area is large, you may want to lay new sod for faster coverage after you have loosened the soil. Remember, if the wear and tear continues as before, the grass will disappear again.
One of the leading causes of decline in turf quality is shade. As trees age, they grow larger and create more shade in the landscape. Areas where grass grew well before eventually become too shady for grass to thrive. All of our permanent warm-season grasses prefer sunny areas.
The amount of sunlight reaching the turf can be increased by selectively pruning trees in your landscape. Raising and thinning the canopy on older, mature trees is often done best by a professional arborist who can determine which branches should be removed without adversely affecting a tree. After this is done, the existing grass (hopefully) will do better, but if the grass has died out in the area, you can lay new sod and see if it will take. Remember this is a temporary solution, because the trees will continue to grow over the years and shade will once again become a problem.
St. Augustine grass (Palmetto may be the most shade-tolerant cultivar currently available) is considered the most shade-tolerant of the grasses for our state. No lawn grass, however, will reliably grow with less than four hours of direct sun, so don’t expect them to grow in heavy shade.
Keep in mind that it still too early to fertilize your lawn. Research has shown that turf grass does better if you wait until early April to make the first application of fertilizer to your lawn. Don’t forget that advice also pertains to weed-and-feed products that contain herbicides to kill weeds and lawn fertilizers.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.