Take-All Root Rot in Warm-Season Lawns: Complete Guide

Take-All Root Rot (TARR) is particularly insidious because significant damage occurs below ground before you notice any problems with your lawn. The disease, caused by the fungus Gaeumannomyces graminis var. graminis, attacks the roots and stolons of St. Augustine grass, disrupting the plant's ability to absorb water and nutrients. By the time symptoms appear above ground, extensive root damage has already occurred.

The first visible symptoms are often subtle - irregular patches of grass that appear yellow-green or chlorotic, as if the lawn is nitrogen-deficient. The grass in these areas thins out gradually, with individual plants dying seemingly at random. Unlike Brown Patch's distinct circular patterns, TARR damage appears more diffuse and irregular, often following drainage patterns or appearing in areas with poor soil conditions.

When you pull on affected grass, it often releases easily from the soil because the roots have been destroyed. Examining the roots and stolons reveals the key diagnostic sign: they appear dark brown to black and rotted, rather than the healthy white or cream color of normal roots. The stolons (runners) may also show black discoloration at the nodes where they contact the soil.

In severe cases, TARR can kill entire sections of St. Augustine lawn over the course of one or two growing seasons. The disease progresses slowly but relentlessly, and affected areas rarely recover on their own. In Florida, TARR is often triggered by stress factors like excessive rainfall, poor drainage, soil pH issues, or overly aggressive herbicide applications.