Necrotic ring spot is a lawn disease caused by a soil-borne fungus. It typically appears in the spring, when environmental conditions favor fungal development, particularly when temperatures range between 10 and 20 °C (50-68 °F) and when the soil experiences excess moisture or periods of drought stress.
This disease is characterized by the appearance of circular patches of dead grass measuring approximately 10 to 25 cm (4 to 10 inches) in diameter. A typical symptom is the presence of a tuft of green grass in the center of the ring, creating a distinctive donut-like pattern. As the infection progresses, multiple rings may merge together to form larger areas of damaged turf.
Necrotic ring spot usually affects lawns that are weakened by poor soil conditions or improper lawn care practices.
Several cultural practices can help reduce the severity of this disease:
- Avoid excessive fertilization, particularly with nitrogen.
- Maintain a higher mowing height, which helps the grass tolerate stress.
- Dethatch the lawn when necessary to reduce excessive organic buildup.
- Aerate compacted soil to improve air, water, and nutrient movement.
- Avoid excessive irrigation, especially during hot and dry periods.
A balanced lawn care program - including proper fertilization, soil aeration, and appropriate watering practices - helps strengthen the natural resistance of turfgrass against diseases such as necrotic ring spot.
What is necrotic ring spot in a lawn?
Necrotic ring spot is a turfgrass disease caused by a fungus living in the soil. It creates circular patches of dead grass, often with a small tuft of green grass in the center.
When does necrotic ring spot usually appear?
This lawn disease most commonly appears in spring, when temperatures range between 10 and 20 °C (50–68 °F) and soil conditions promote fungal activity.
Why are there circular dead patches in my lawn?
Circular patches of dead grass are often caused by soil-borne fungal diseases such as necrotic ring spot. Soil compaction, excessive fertilization, and poor irrigation practices can increase the risk.
How can necrotic ring spot be prevented?
Prevention includes:
- maintaining proper mowing height,
- avoiding excessive fertilization,
- aerating compacted soil,
- dethatching when necessary,
- following proper watering practices.
Is necrotic ring spot common in Quebec lawns?
Yes. Necrotic ring spot is relatively common in Quebec lawns, particularly in urban areas where soil compaction and moisture fluctuations occur.
Do you offer lawn disease diagnosis and treatment in the Montreal area?
Yes. We provide lawn care services and lawn disease diagnosis throughout the Greater Montreal area and the South Shore, including Longueuil, Brossard, Boucherville, and nearby communities.
sur la Rive-Sud
