Problem: Anthracnose (Lawns)
Problem Info
In the summer and fall, irregular areas of reddish-brown to light-tan grass appear in the lawn. These areas may range from 2 inches to 20 feet in diameter. Small, oval, reddish-purple spots occur on the blades. A fine webbing may cover the spots, or tiny black specks may be seen in the spots. The disease is active in warm, humid weather and grass may be killed within 2 days. Anthracnose can infest all turfgrasses but is most severe on bluegrass.
Analysis
This lawn disease is caused by a fungus (Colletotrichum graminicola) that attacks lawns under stress, especially those that are poorly fertilized or underwatered. The disease is active in warm (80° to 85°F), humid weather and results in root decay and stem rot. When weather conditions are favorable for the disease, grass may be killed within 2 days. Although anthracnose can infest all turfgrasses, it is most severe on bluegrass.
Solution Advice
This lawn disease is caused by a fungus that attacks lawns under stress, especially those that are poorly fertilized or underwatered. Reduce potential damage from anthracnose by fertilizing with phosphorus and potassium and by watering as needed.
