Anthracnose in Warm-Season Lawns: Complete Guide

Anthracnose is a fungal disease complex caused by Colletotrichum species that affects stressed turfgrass throughout Florida. The disease has two distinct phases: foliar blight and basal rot. Both can occur simultaneously, making Anthracnose one of the more complex lawn diseases to diagnose and manage.

In the foliar blight phase, Anthracnose creates irregular yellow patches in the lawn that gradually turn reddish-brown to bronze. Individual grass blades develop elongated lesions that start yellow and develop distinctive black centers - these dark spots are the fruiting bodies (acervuli) of the fungus and are a key diagnostic feature. Close examination of infected blades with a magnifying glass reveals tiny black spines (setae) extending from these spots.

The basal rot phase attacks the base of grass plants and stolons, causing a wet, dark rot at the crown and nodes. This form is more damaging and can kill entire plants as it destroys the growing points. Affected grass pulls up easily, and you may notice dark, water-soaked tissue at the base of the plants. In severe cases, large irregular areas of turf can thin out and die.

Anthracnose is often called a "disease of stressed turf" because it primarily attacks grass weakened by other factors. Drought stress, soil compaction, low mowing, excessive traffic, and nutrient deficiencies all predispose lawns to Anthracnose. In Florida, outbreaks commonly occur during the heat of summer when lawns are under multiple stresses simultaneously. The disease can also develop in fall when grasses are recovering from summer stress.