Pholiota populnea

Pholiota populnea is a wood-decaying fungus that acts as a dangerous pathogen, causing brown central heart rot in tree trunks. The pathogen belongs to the Strophariaceae family and is classified as a parasitic xylotroph. In forest and urban ecosystems, it infects living trees that are already weakened, entering the wood through bark wounds, pruning cuts, or frost cracks.

The primary hosts affected by this disease are trees of the genus Populus, including black poplar, Lombardy poplar, and balsam poplar. Less frequently, the fungus is observed on other hardwood species such as willow, aspen, or maple, particularly if these trees are growing under stress factors that compromise their natural defense mechanisms.

Symptoms of the infection become visible when the characteristic fruiting bodies of the fungus emerge from the bark. The wood itself undergoes significant structural changes: in the areas colonized by mycelium, the wood turns brownish, loses its structural integrity, and begins to crumble. In advanced stages, the heartwood transforms into rot, which leads to a severe loss of mechanical stability, creating a high risk of the tree falling during heavy winds.

The conditions favorable for the development of the fungus are closely linked to high humidity and the presence of entry points for the fungal spores. Spore dissemination occurs via air currents during the peak fruiting season, which generally occurs in late summer and autumn. The optimal environment for mycelial growth is dead or weakened woody tissue with a high lignin content, which the fungus decomposes through active enzymatic processes.

The economic and ecological impact of Pholiota populnea includes premature tree death and a reduction in the ornamental or commercial value of wood stands. Prevention and management strategies include maintaining high silvicultural standards: timely pruning of dead branches, proper treatment of pruning wounds with protective sealants or fungicides, and preventing mechanical damage to the tree bark during maintenance. If active fruiting sites are identified, sanitary removal of severely infected specimens is recommended to prevent the spread of spores to healthy trees.