Preventing Common Lawn Diseases

Over our 21 plus years in business we have seen how warm wet weather in late spring and summer, combined with overwatering of lawn can cause lawn diseases or fungus. There are two main diseases we see here in Virginia that can all be prevented by good lawn care practices and proper watering.  Tall fescue is the most common turfgrass species in Virginia. The most common and troublesome diseases for tall fescue are brown patch and red thread.

Brown patch

Brown patch occurs most frequently during warm and wet weather, but the lawn typically recov­ers in the fall when managed properly. However, heavy brown patch infestation combined with drought or heat stress can cause the infected areas to die so it is important that it be treated. Brown patch appears as roughly circular patches that are brown, tan, or yellow in color and range from 6” to several feet in diameter.

Red thread

Red thread occurs most frequently in the spring and fall. The symptoms of red thread create an undesirable appearance, however, since the roots of the grass are not infected, the turf will likely recover with a proper lawn care program. Red thread appears as circular patches of tan or pink turf about 4-8 inches in diameter. The bright red to pink mycelial growth of this fungus is plainly visible early in the morning, particularly when the dew is still on the grass. The disease will remain an eyesore as long as cool, moist periods persist, but the fungus only attacks the foliage and rarely will the entire plant die.

There are several lawn care practices that can help prevent lawn diseases and fungus:

·         Fertility: Turfgrass plants are healthier when steady supplies of nutrients are available, as opposed to spikes in nutrient levels that may result in rapid growth. Therefore, having a lawn care program, like our 6-step program, will ensure your lawn receives the nutrients it needs throughout the year to fight off disease.

·         Irrigation: It is impossible to control rainfall, but homeowners do have control over the frequency and duration of lawn irri­gation. The ideal time to irrigate for minimizing disease, is around sunrise. This decreases the leaf wetness period, which is critical for disease development, and rinses the leaves of dew that attract fungi.

·         Mowing height: In most cases, turfgrass that is cut too short is more susceptible to disease. Tall fescue lawns should be between three and four inches, especially during periods of heat and drought stress.

·         Air Movement: Areas with poor air circulation have more turf diseases. Strategic pruning of trees and shrubs is a good way to improve air movement and allow additional sunlight into trouble areas.

·         Fungicide: There are a number of commercially available biological fungicides that may reduce the severity of turfgrass diseases. The majority of these products contain beneficial bacteria or fungi. No biological fungicides tested in Virginia provide complete control of turfgrass diseases. However, several fungicides suppressed dis­eases, such as brown patch and dollar spot, and aided in turfgrass recovery.