Lawn diseases are common in lawns that are not properly taken care of or in those lawns that face extreme weather conditions throughout the growing season. Although some diseases cause only a little damage, poorly managed lawns with little defense against disease may see catastrophic damage. Effective control requires both cultural and chemical control in the lawn.
Identify the lawn disease before attempting treatment. Treatment for disease will depend on the disease present in the lawn. Knowing the grass variety of your turf will narrow down the possible diseases. Contact your university extension for a disease identification key or send samples of the grass to the extension service for diagnosis.
Inspect the turf for the likely cause of the disease. Determine your grass variety and the diseases likely to attack it. Look for symptoms including powdery mildews, greasy looking spots or dead grass. Check the soil moisture in spots that are brown or wilted, since these areas might require water. Look for signs of insects in the lawn to rule out insect infestation as opposed to disease. Some insects do cause disease, however, so check the disease symptoms against a fact sheet obtained from your university extension.
Properly fertilize the lawn to increase root depth and foliage strength. A healthy, vigorously growing grass will prevent the development of many diseases. Diseases such as dollar spot require an infertile lawn to develop, according to the Clemson University Extension. It is important to fertilize only as much as necessary. Excessive nitrogen will cause top growth and weak grass. One pound of fertilizer per 1,000 square feet is usually all that is necessary, says North Dakota State University.
Mowing and Thatch
Cut only one-third of the grass blade at a time. Proper mowing practices prevent the development of disease by reducing the stress to the grass. Use a sharp mower blade to prevent ripping up the grass. Remove excessive thatch from the lawn to reduce the chance of diseases from developing in the dead plant material. Reduce thatch that is 1/2 inch thick or greater by using a power rake or by aerating.
Chemical control of diseases may be necessary. Apply and mix fungicides according to the packaging instructions. Apply the correct fungicide for the disease present in the lawn. Spray on a day with little wind and no chance of rain for at least 48 hours.