By early summer, many lawns will show signs of the disease brown patch.
General symptoms appear as small circular patches of brown, lifeless grass, but specific symptoms vary depending on the turf grass species and mowing height. These patches often enlarge and reach diameters of six feet or more.
The most common lawn grass that will show signs of brown patch (Rhizoctonia solani) is tall turf fescue. However, other turf species like zoysiagrass can also be affected.
Grass is most susceptible for brown patch when it is growing vigorously, and daytime temperature range between 75 and 85 degrees Fahrenheit, free moisture is present on the foliage, and night temperatures fall below 68 degrees.
The fungus can live on dead organic matter in the soil and attack grass when the right conditions arise. Hot, humid conditions promote the spread of the disease.
Prevention
There are ways to prevent the disease.
1. For starters, fertilize correctly. Avoid heavy, early spring and summer fertilization. Then, continue fertilizing during the growing season to maintain adequate, but not lush, growth.
2. Prune back thick growths of trees and shrubs to allow air movement and light to reach the turf grass.
3. Mow only when the grass is dry and remove no more than one third of the top growth. It is also best to remove and dispose of clippings from infected areas.
4. Watering no more than once or twice per week can help prevent the disease from spreading. More frequent watering (or watering at night) provides an ideal environment for disease development.
Treatment
If brown patch is already well established in the lawn, a fungicide program may be required.
Some chemical treatments may suppress the disease, but it is not guaranteed. The treatment can be expensive even if you do it yourself.
When making a fungicide application, it is best to treat the entire lawn instead of only the infected areas.
If only the leaf blade is affected, the grass will come back when growing conditions are more favorable. However, if the disease reaches the crown of the grass plant, it may be killed and must be reseeded in the fall.