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MAY GARDENER: Fix dead spots in centipede lawns

James Morgan is the Dougherty County Extension Coordinator for the University of Georgia’s College of Agricultural and Environmental Sciences. (Staff photo: Laura Williams)

James Morgan is the Dougherty County Extension Coordinator for the University of Georgia’s College of Agricultural and Environmental Sciences. (Staff photo: Laura Williams)

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Pro-active measures can help prevent dead spots that often occur in centipede lawns. (Special photo)

Late winter and early spring for me is the time frame in which I am the most active at the start of a new year. I begin making recommendations for fruit trees and crape myrtle trees in mid-February. March 1st starts the beginning of a homeowners weed control program. Then the grass starts to green- up over the next few weeks. Around the end of March, calls start coming in fertilizing lawns. Our recommendation for soils temperature has changed as it relates to fertilizing lawns. We now require that a homeowner waits until soil temperature is consistent at 70 ºF. You can visit www.GeorgiaWeather.net for this and more information related to the weather.

As the grass continues to green up around the 1st of April, I will receive calls concerning dead spots in the lawn and this year was no exception. I have received many calls and conducted many site visits around the county on this very topic. I have collected samples and sent photos to the plant pathology lab in Athens. This is what I have discovered.

Due to the heavy rain of late last summer and the winter from as well as early spring rains we have had in the last couple of months, centipede lawns have suffered several problems. These problems include centipede decline, the diseases large patch and take-all root rot as well as environmental stress like abiotic disorder (lack of oxygen taken up you the roots).

Now with proper replanting or management your centipede lawn can recover from these issues. Below are recommendations from the plant pathology lab.

Give the lawn time to green up completely. Fungicides will not work well on dead or dormant grass. A fungicide application could be made now although fall before dormancy is the best time to treat for Rhizoctonia (Large Patch) and take-all root rot. In the meantime, optimize plant health:

1) Obtain a soil test.

2) If needed based on the soil test apply moderate amounts of phosphorous and moderate to high amounts of potash. During the active growing season, use low to moderate amounts of nitrogen applied as slow release or over several applications. Avoid applying nitrogen when disease is active. Do not apply any nitrogen after August or before May in Georgia on warm season grasses. Early and late season nitrogen applications can encourage this disease and other problems.

3) Maintain a pH of around 5.0 to 5.5 to discourage disease. Soils can be acidified by fertilizing with ammonium sulfate as a source of nitrogen, but avoid rapid changes in pH.

4) Water infrequently but deeply only as needed (watering once a week at a depth of 3-4” or about an inch of water is sufficient when rain is insufficient). Water when the grass will dry quickly such as in the morning.

5) Reduce thatch if it is more than 1 inch thick.

6) Avoid applications of herbicides on affected areas of the lawn. 7) Improve the soil drainage of the turf with aeration.

8) Increase the height of cut to the maximum recommended for the type of turf.

9) Top-dressing with sphagnum peat moss or compost has proven to reduce symptoms of disease in home lawns. Adding this organic matter could improve the general health of the lawn. The recommended rate is 3.8 cu ft. sphagnum peat moss/1000 sq ft).

10) October would be the best time to apply fungicides if desired. See the current Georgia Pest Management Handbook for Homeowners for more information on fungicides. Check fungicide labels for specific instructions, restrictions, special rates, recommendations and proper follow up and handling.

For more information on centipede decline, large patch and take-all root rot, submitting soil and plant samples, fungicide recommendations or to make an appointment for a site visit, please call me at 229.436.7216 or 229.343.5097. You can also email me at morganjl@uga.edu.

James Morgan is the Dougherty County Extension Coordinator for the University of Georgia’s College of Agricultural and Environmental Sciences.