A lush, rich-green appearance is the sign of a truly healthy lawn. But an unhealthy lawn can display an array of symptoms that include rusting, wilting, growth stunt, browning and yellowing. Diseased grass can be a certain nuisance, but most lawn diseases can be controlled and prevented.
There are several lawn diseases that can quickly stress your grass. Many are similar to plant and tree diseases, and most are fungal-based. They include leaf spot, fusarium blight, ring spot, summer patch, dollar spot, rust and powdery mildew. While some of these diseases are soil-borne, most are transported by air and windswept fungal spores. These spores have a greater chance of successful infection when the grass is stressed and poorly maintained.
Balanced irrigation is essential for your lawn's healthy growth. Too much or too little water can cause your lawn to be stressed and thus highly susceptible to disease. Healthy lawns should be irrigated at least once a week throughout the growing season. The lawn should be irrigated deeply to ensure the water reaches the roots deep below the surface. The irrigation should be adjusted for long periods of rain and drought to ensure that the lawn gets the proper amount of irrigation.
A healthy lawn is a result of proper fertilization as well. Lawns require proper nutrients for vigorous growth. Similar to irrigation, over- and under-fertilization can result in an unhealthy and disease susceptible lawn. When fertilizing your lawn, the Ohio State University Cooperative Extension says you should use a balanced, slow-release fertilizer that has higher levels of nitrogen, such as a 20-10-10 or 10-5-5 combination.
Thatch and Aeration
Throughout the year, your lawn develops a layer of buildup that results from mowing, raking and shedding of the lawn. This buildup, known as thatch, lies between the soil and the grass line. While a thin layer of thatch will protect the lawn's roots from sunburn and harsh weather, a thick layer can suffocate the lawn while preventing nutrients, sunlight and water from reaching the roots. Like improper irrigation and fertilization, a thick layer of thatch will cause your lawn to become stressed and more susceptible to disease.
Most lawn diseases can be controlled and treated with chemical fungicidal treatments. But in order for these chemicals to be effective, they must be applied according to the directions and in a timely fashion. In addition, chemical treatments will not be effective if the infected lawn does not receive the proper combination of lawn maintenance, including timely irrigation and fertilization, annual to biannual thatching and regular mowing and trimming. In addition, it is important to select the chemical treatment that meets the needs of the actual disease. Speak with your local horticultural or nursery specialist for disease diagnostic assistance.