Further north, this disease is usually seen just before the first frosts in the fall and shortly after green-up in the spring. Tall fescue lawns are damaged by brown spot during hot, wet summer weather. Brown patch first appears as small brown areas a few inches in diameter. These patches quickly increase in size and merge together, forming large patches of damaged turf. On St. Augustinegrass, these patches may reach 20 feet in diameter.
Damage is often worse on shaded lawns.
Good management often helps prevent outbreaks of brown patch. Apply low rates of nitrogen fertilizers monthly through the growing season. Avoid fertilizing St. Augustinegrass, zoysiagrass and centipedegrass with high rates of nitrogen shortly after spring green-up. For tall fescue, do not apply high rates of nitrogen in the summer. To speed evaporation of dew, prune trees and shrubs to increase sunlight penetration and increase air circulation.