Large Patch in Lawns
Our southern climate is a perfect catalyst and climate for pest pressure: diseases never truly disappear with our winter weather, our spring and fall are often cool and damp which favors growth of many fungal diseases and our summer weather nurtures bacterial and fungal disease with high humidity and cozy temperatures. An interesting pattern observed with this weather shows plants sustain damage in a cooler season, such as fall, but the damage remains hidden until a warmer season like summer. A perfect example of this is large patch disease in centipede lawn.
Right in the middle of the warmest months when we’d love to have a thick, green lawn to relax on, we can see patches of dead grass in our lawn—not good! Unfortunately, by the time we see the dead centipede, large patch has already taken hold. Large patch can be overlooked in the early stages as the patches may be on the smaller side and the actual fungus kicks in during the cool autumn months. Damage becomes visible once the rest of the lawn greens up while affected areas stay brown.
As with many fungal diseases, large patch can be countered, somewhat, by the use of fungicides but it cannot be cured. The best bet is to use cultural practices to prevent large patch from gaining a foothold; happy grass is healthy grass! Get your soil tested every year to see what nutrients to apply and if your pH needs to be adjusted. Using fertilizers with heavy nitrogen in the spring and fall will unnecessarily push your lawn and stress it out. Avoid watering in the afternoon and evenings as your lawn will be damp during the coolest hours of the day—this encourages the spread of disease. If you can, avoid trying to establish centipede in low-lying areas that say wet as this will stress it further. Centipede is also sensitive to thatch buildup; remove once it accumulates to half an inch as this will promote air circulation and healthy growth.
If you must use a fungicide, you can begin applying products containing azoxystrobin or fluoxastrobin once temperatures are around 60F and continue reapplying every 2-3 weeks. If temperatures drop down below 60F for more than 5 days in a row, stop applications. While this won’t fix the problem, it can help improve the appearance of your lawn.
As always, if you have further questions about your lawn, stop by your local extension office!
Selena McKoy is the Horticulture Agent at North Carolina Cooperative Extension in Harnett County.