With warm days and cool nights, we are beginning to see turfgrass diseases like this I found yesterday. I was able to look at some centipede turfgrass under the microscope and confirmed it to be Large/Brown Patch (below).
Rhizoctonia produces distinct mycelia with three characteristics for diagnostics: 1) septate hyphae that branch at 90 degree angles, 2) constrictions at the base of the branching, and is 3) tan to light brown color. Large/Brown Patch will infect in the Fall and Spring when temperatures reach over 80 degrees during the day and stay above 60 degrees at night. During the summer, I commonly find Take-All Patch which can really cause problems.
If this disease persists, UGA Extension Pathologist, Dr. Alfredo Martinez, recommends a fungicide application in the Fall followed by one in the Spring. As with most turf diseases, long-term cultural management is best. Here are some management for Brown Patch:
- Use low to moderate amounts of nitrogen, moderate amounts of phosphorous and moderate to high amounts of potash.
- Avoid nitrogen applications when the disease is active.
- Increase the height of cut.
- Increase the air circulation.
- Minimize the amount of shade.
- Irrigate turf early in the day.
- Improve the drainage of the turf.
- Reduce thatch.
- Apply lime if soil pH is less than 6.5
- Remove dew from turf early in the day.
- Fungicides are available to control the disease. Consult the 2014 UGA Georgia Pest Management Handbook.
Centipedegrass also succumbs to an environmental disordered termed “Centipede Decline.” Dead patches can be caused by this where centipede has been stressed and over-fertilized/managed. It is good to avoid weed control during green up. Make sure not to fertilize too early – generally late April/Early May is good fertilizing timing. Centipede does not like more than 1 lb of nitrogen/1000 sq ft in a season, so do not over-fertilize.
Here is a link to the Turfgrass Diseases in Georgia: Identification and Control.