Does your lawn have dead spots or brown patches? Centipede grass could be the culprit.
“I spoke with many concerned homeowners over the last month about the appearance and health of their centipede grass. One of the following factors or a combination of them can be the reason for these bad areas in your centipede lawn: excessive nitrogen applications, excessive thatch, winter injury, insects or disease,” said Bill Tyson, County Agent for the Bulloch County Cooperative Extension of the University of Georgia.
According to Tyson, centipede grass does not green up as quickly as some other warm season turf grasses.
Temperature and day length are the two factors which influence when centipede grass comes out of dormancy and the rate at which the grass greens up.
Problems with centipede lawns often develop three-to-five years after establishment. These problems can generally be related to mowing heights more than two-inches high, annual nitrogen applications of more than two pounds per 1,000-square-feet, or early spring or late fall fertilizations.
Excessive nitrogen applications during last year's growing season and/or fertilizer applications made too early in the spring makes the grass more susceptible to winter injury.
Lawns with excessive thatch are also more likely to have received winter injury because of the extra distance between the stolons and the soil surface.
Insects could also be causing the problem. Mole crickets and grubs can cause excessive root damage.
“If you have mole crickets in your yard, you probably have considerable root damage. The adult stage of the mole cricket is the only one active at this time. The adult is hard to kill - you almost need two bricks - and now is not the ideal or appropriate time to treat for mole crickets. You may have to treat or contact a landscape professional to make an application if they are causing excessive damage to the turf and cannot wait until June to treat for the young mole crickets,” said Tyson.
Disease is another factor that could be causing problems. Take-all patch and large patch are common problems noticed in centipede. Proper identification of the disease needs to be attained, so control measures for it can be followed.
Centipede is susceptible to yellowing or iron chlorosis. The chlorosis may be caused by one or more of the following factors:
- Excessive nitrogen or nitrogen applied during spring green-up
- High soil pH, phosphorus or potassium levels
- An excessive thatch caused by over-fertilization
- Irrigation or pesticide use
- Poor mowing
Iron chlorosis can be temporarily overcome by spraying two ounces of ferrous sulfate per 1,000-square feet or a chelated iron material according to label rates. An excessive application of iron will appear within a few hours as blackening of the leaves. The grass may take a few weeks to fully recover from such high rates of iron. However, the real solution is to determine and correct the cause of chlorosis.
"Your lawns may be showing signs of a combination of the factors I have mentioned. Try not to get over anxious with your fertilizer application this spring. Be patient - wait until your lawn is at 100 percent green-up and the soil temperatures have risen (usually late April/early May). If your turf has some disease issues, excess nitrogen and water may benefit the progression of the disease," Tyson said.
Here are a few management practices that will enhance the growth of your centipede lawn:
- A fertilization program should be based on a soil test analysis
- Fertilize lawn after spring green-up and again in mid-summer with a complete fertilizer. Do not exceed two pounds of nitrogen per 1,000-square feet per year
- Mow your centipede lawn at a height of one to 1½". Try to avoid thatch buildup
- Irrigate your lawn during periods of drought stress. Apply enough water to wet the soil to a depth of six to eight inches
- Identify insects and diagnose diseases in your lawn and treat accordingly
For more information, contract Tyson at wtyson@uga.edu or call the Extension office at (912) 871-6130.