What causes a fairy ring in turf?

A fairy ring in turf is primarily caused by the growth of certain fungi, such as mushrooms or puffball fungi. These fungi form a circular pattern as they decompose organic matter in the soil, which leads to visible rings of grass that are often darker or greener compared to the surrounding area. This phenomenon occurs because the fungal mycelium spreads outward from a central point, and as it does so, it introduces nutrients into the soil that can affect the grass growth in these areas.

The appearance of fairy rings can also vary based on the type of fungus involved, as some types may cause the grass within the ring to thrive, while others might suppress growth, leading to a yellow or even dead patch in the center. Thus, understanding the role of fungi is crucial in recognizing and managing fairy rings in turf.

In contrast, excessive irrigation, low mowing height, and chemical imbalances in the soil do not directly create the fairy ring phenomenon, although they might contribute to turf health in general or stress conditions that could either exacerbate or mitigate the visibility of such rings. However, the fundamental cause of fairy rings remains the activity of specific fungi.