Most lawn diseases are fungal in nature, appearing from early spring to late fall, manifesting from minor discoloration to swift turf death, such as in brown patch disease.
Turf diseases are very difficult to diagnose in a home lawn due in part to the complex nature of the appearance as it relates to air temperature, mowing height, fertility, thatch thickness, and moisture present on the lawn surface. Like an episode of CSI, diagnosing and treating lawn diseases requires experience and a future game plan for successful treatment. By the time most people see the damage appear in their home lawn, the fungal disease has manifested as brown spots or dead patches. Since most lawn diseases are fungal in nature, they love humidity or moisture in order to activate and complete a life cycle, be it brief. Temperature also plays a huge role, from the cool weather of snow molds to the high heat and humidity required to see brown patch disease.
June of 2011 has brought about an unusual set of weather phenomena from cool wet days to hot, moist nights several weeks ago. The result of this kind of weather predisposes home lawns to multiple disease infections. The best offense is a good defense in these kinds of circumstances. First, any watering should be done in the am or daytime, allowing the lawn to dry out in time for nightfall. Grass left wet over night sets the stage for all kinds of fungal diseases. Your mowing height is very important during the summer and should be kept at or near 3”. A shorter cut predisposes the lawn to stress and assists in the ability of disease to not only manifest itself, but cause more damage than a lawn cut properly. I cannot stress the importance of proper mowing height, especially in the June through August time frame.
Thatch management through core aeration is a critical process that can help minimize patch diseases when done in the spring or fall. Overseeding with disease resistant grass varieties can also help prevent the future visual annoyance of dead or brown patches caused by patch diseases. If your lawn has confirmed disease issues, the use of fungicides may be desired to help reduce the occurrence of especially serious ones like Brown Patch, Necrotic Ring Spot, Fusarium Blight, Pythium, or Summer Patch.
Slow-release fertilizers should be used during the summer months as excessive fertility can lend to the appearance of certain diseases under the right conditions. On a good note, red thread, minor leaf spot, and powdery mildew are generally not lethal and usually more aesthetically displeasing than damaging. The key to any great lawn is maintaining a balance and doing many “little” things right to keep a healthy balance. When it comes to lawn diseases, heat and humidity generally set the stage for a fungal outbreak in your lawn. If you think you have an ongoing disease issue in your lawn, have an experienced, qualified person check things out. This way, a plan can be put into place, be it a fungicide treatment now or setting up core aeration for this fall. Left unchecked, some diseases can damage your sod or bluegrass lawn, causing scars, depressions, or thin areas. June of this year seems to be one filled with diseases so far – I can hardly wait for July!