If the crowns of individual plants or stolons are invaded, large areas of a lawn may be killed. Control Measures Nitrogen fertility has a significant impact on brown patch development. High nitrogen levels promote the growth of soft, succulent leaves that are susceptible to attack by the brown patch fungus. To reduce the risk of disease outbreaks during the winter and early spring, avoid fall and late winter applications of high rates of nitrogen fertilizer. Finally, maintain phosphorus and potash fertility levels according to soil test recommendations.
Moisture also plays an important role in disease development.
Good drainage is needed to remove excess water from low-lying areas. To speed evaporation of water from the foliage, prune nearby trees and shrubs to reduce shade and improve air movement and sunlight penetration. Also, irrigate lawns at midday to minimize the time that the foliage remains wet. Thatch harbors the brown patch fungus. Periodic mechanical dethatching or core aerification is needed to prevent thatch buildup, especially on high-maintenance St. Augustinegrass and zoysiagrass lawns.