Fusarium Blight on Lawns

Fusarium blight is a lawn disease that affects cool season grasses such as bluegrass, tall fescue and bentgrass. It occasionally attacks warm season grasses as well and strikes when lawns are under drought stress during hot, humid conditions. Fusarium roseum and Fusarium tricinctum are the common fungi that cause Fusarium blight.

Fusarium blightFusarium Blight Symptoms
Initially, grasses affected by Fusarium blight display light green patches that are 2- to 6-inches in diameter. The shape of the affected areas may appear as circular patches,  crescents or elongated streaks. At high temperatures, the patches quickly change from light green to reddish brown, then tan and finally to straw-colored.

At this stage the disease displays symptoms characteristic of a doughnut-shaped area up to 3 feet in diameter. It displays a pattern that resembles a “frog-eye” – with healthy grass in the center of the diseased area. When conditions of high humidity and high temperature persist for an extended time, these diseased areas can multiply and may overlap. As a result, blight may appear to have taken over an entire area of turf. It is important to control fusarium blight before the disease progresses, when the grass dies as the crown and root tissues are destroyed.

Excessive watering creates conditions more favorable for the fungi . Also, high nitrogen levels favor fusarium blight when there are greater accumulations of thatch.

Fusarium Blight Control
Planting mixtures of bluegrass with perennial ryegrass can prevent Fusarium blight in areas of bluegrass. Otherwise, a program to control thatch together with a fungicide like ZeroTol or ZeroTol RTS (Ready-to-Spray), that is specifically labelled for Fusarium control is essential for effective control of fusarium blight.