Agrocybe cylindracea

Agrocybe cylindracea is a fungus known primarily as a saprotrophic and parasitic organism that causes white rot in the wood of various deciduous trees. While recognized in culinary circles as a gourmet mushroom, in forestry and horticulture, it is categorized as a pathogen that contributes to the decay of standing timber. It penetrates the host through bark fissures, broken branches, or pruning wounds, initiating the degradation of lignin and cellulose.

The host range of this fungus includes a variety of deciduous trees such as poplars, willows, maples, and various fruit trees. Weakened, aged, or poorly maintained trees are at the highest risk of infestation. The fungus behaves as a typical wood-decay agent, colonizing the sapwood and heartwood, which eventually leads to the structural compromise of the tree's trunk or main branches.

Signs of infestation include the appearance of dense clusters of fruiting bodies emerging from cracks in the bark or near the base of the tree. The internal symptoms involve a distinct whitening of the wood, accompanied by a significant reduction in wood density and the presence of dark zone lines between areas of different decay stages. In advanced cases, the tree becomes hollow and structurally unstable.

Environmental conditions that favor the spread and development of the fungus include high humidity, moderate ambient temperatures, and the presence of exposed or necrotic wood tissue. Spores are primarily disseminated by wind or rain splash. Once an infection point is established, the mycelium spreads systemically throughout the trunk, especially in orchards where sanitary pruning is neglected.

Effective management strategies focus on prevention and structural health:

• Pruning and destroying infected branches to prevent spore production.
• Sealing large pruning wounds and trunk injuries with protective pruning paints.
• Improving air circulation in the orchard to minimize humidity around the trunks.
• Monitoring the health of older trees and treating potential entry points for pathogens immediately.