Brown Patches Might Be Result of Improper Lawn Maintenance
Q: What is the cause of brown patches and dead spots in my centipede lawn?
A: Centipede decline is a term used to describe common problems seen in centipede lawns. These common problems result in a lawn with dead, brown spots. When most of us see these spots in our lawns, we want to know the cause and how to get rid of it.
Unfortunately, there are several possibilities as to what is causing the dead spots, making it difficult to determine the cause. Factors that could result in centipede decline include pest problems, like large patch, fairy rings, nematodes, and ground pearls. Other problems that can result in centipede decline are nutritional problems and poor lawn maintenance practices. Since there are several possible problems that can result in centipede decline, this week I’ll cover some of the nutritional and lawn maintenance problems. Then next week, I’ll cover some of the possible pest problems that can lead to centipede decline. So, don’t forget to check next week’s article for the rest of the story.
Centipede decline has been associated with nutritional factors, including low potassium levels in sandy soils, high phosphorus levels, the use of too much nitrogen fertilizer, and low or high soil pH. A pH of 5.5 is the best for centipedegrass. High soil pH will cause centipedegrass to turn bright yellow, especially in the spring, due to iron deficiency (iron chlorosis). High phosphorus levels can increase iron chlorosis since it can replace iron in the plant. The use of fertilizers high in phosphorus may contribute to the decline of centipedegrass. A soil test report should be used to correct these problems and to determine fertilizer requirements.
Improper mowing and fertilization have been found to be factors that can contribute to centipede decline. Some research has indicated more centipedegrass decline when the grass was mowed at 2 inches than at 1 inch and where high nitrogen rates were used. The high nitrogen rates plus the higher mowing height caused excess thatch accumulation resulting in the grass growing in the thatch layer and not in the soil. These grass stolons (stems) above ground are more susceptible to damage by cold weather. More centipedegrass decline usually occurs in the spring and summer following very cold winters or following winters with unusually warm weather and then late cold periods.
Thatch is a term used to describe the layer of living and dead organic matter that occurs between the green matter and the soil surface. Having a small thatch layer is ok in a lawn, but the thatch layer should not be over 1/2 inch thick.
The cutting height for centipedegrass should be 1 inch. Recommendations for fertilizing centipedegrass are 0.5 pounds of nitrogen per 1,000 square feet applied in June. The use of fertilizers that are high in potassium and low in nitrogen may help to reduce stress during the summer and winter. Centipedegrass has a naturally light green color when managed properly. If a darker green lawn is desired in the lawn, another type of grass such as bermudagrass or zoysiagrass should be considered.
The use of certain herbicides has been associated with centipede decline. Centipedegrass is very sensitive to some herbicides, like 2, 4-D and dicamba, and recommended herbicides should be used according to label directions for centipedegrass. Damage has been observed where fertilizers containing some types of herbicides have been applied at rates suggested for other types of turfgrasses. Products with herbicides plus fertilizers can causes problems not only due to herbicide damage but also due to too much nitrogen being applied for centipede. With any herbicide product, make sure to read the label to determine if the herbicide can be used on centipedegrass and only apply the amount recommended for centipedegrass specifically.
Good lawn maintenance and proper fertilization can help reduce the occurrence of centipede decline. For areas in the lawn suffering from centipede decline, centipedegrass will usually spread over the dead areas more rapidly if the old grass is removed and the soil loosened. New sprigs of centipedegrass can be planted in the areas in late spring or early summer for faster recovery.
As I wrote at the beginning of this article, poor lawn maintenance and improper fertilization are only some of the reasons for centipede decline. In next week’s article, I will discuss some the pest problems that can result in centipede decline.
For your gardening, landscape, and lawn questions contact the Wayne County Extension Master Gardener Volunteer Plant Clinic on Mondays and Wednesdays from 10 a.m. to 1 p.m. The plant clinic is a free service open to any citizen in Wayne County that has home gardening questions. One can reach the Wayne County Extension Master Gardener Volunteer Plant Clinic by phone at 919-731-1433, e-mail at Master.Gardener@waynegov.com, or stopping by Room 100 of the Wayne County Extension Office (208 West Chestnut Street, Goldsboro). People contacting the plant clinic with questions are encouraged to bring samples and/or pictures that could help in reaching a solution. Extension Master Gardeners are trained volunteers with the Wayne County N.C. Cooperative Extension Service.
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North Carolina Cooperative Extension
Wayne County Center
P. O. Box 68
Goldsboro, NC 27533