Giant Clitocybe

Giant Clitocybe (Clitocybe maxima) is a basidiomycete fungus that functions primarily as a saprotroph but can adversely affect the rhizosphere of various plants. In the field of agronomy, it is identified as a factor contributing to soil degradation and the suppression of root development in orchard and forest crops through the colonization of decaying organic matter.

This fungus predominantly affects woody species, ornamental shrubs, and trees. It tends to thrive in areas where dead wood, such as stumps and fallen branches, has been left to decay in the soil. By establishing a dense mycelial network, it displaces beneficial soil microflora, indirectly weakening the health and vigor of the surrounding vegetation.

Symptoms of its presence include the appearance of large, circular fungal formations, often referred to as fairy rings, on the soil surface. Host plants show visible signs of distress, including stunted growth, leaf chlorosis, and reduced vitality. These symptoms occur as the fungus depletes essential nutrients from the root zone.

Development and spread are facilitated by high moisture levels, low aeration, and the abundance of raw organic matter in the substrate. The fungus spreads through spores dispersed by air currents and through the continuous expansion of its underground mycelium, which can persist in the soil for several seasons under favorable climatic conditions.

The damage caused by this fungus is primarily related to competition for resources and the disruption of soil structure, which can lead to the slow decline of affected plantings. Prevention and management strategies include:

• Eliminating stumps and decomposing wood from the growing area.
• Improving soil aeration through regular cultivation.
• Maintaining proper drainage to prevent waterlogging.
• Applying preventive soil treatments if colonization is detected.