Aurantiporus fissilis

Aurantiporus fissilis is a destructive basidiomycete fungus known to cause white heart rot in various tree species. As a wood-decay pathogen, it secretes enzymes that break down lignin and cellulose, significantly weakening the structural integrity of the host plant's trunk and scaffold branches.

The fungus primarily targets broad-leaved trees, including apple trees (Malus domestica), oaks, and beeches. It acts as a wound parasite, requiring entry points such as frost cracks, pruning wounds, or mechanical damage caused by agricultural machinery or pest activity to initiate an infection.

The most visible symptom is the development of annual, fleshy fruit bodies on the bark. These sporocarps are initially soft and white to yellowish-orange, but they harden and become brittle as they mature. Internally, the fungus creates a white, stringy rot pattern within the heartwood, which often remains unnoticed until the tree loses stability during high winds.

Environmental conditions that favor the spread of Aurantiporus fissilis include prolonged periods of high humidity and rainfall, which facilitate the dispersal of basidiospores. Once the spores land on a fresh wound, the mycelium begins to colonize the wood, especially in trees that are already suffering from physiological stress or nutrient deficiencies.

The economic impact is significant, as infected trees often become hazardous and suffer from reduced fruit yield or terminal limb dieback. Preventive measures are crucial and include strictly adhering to proper pruning techniques, sanitizing tools between cuts to prevent cross-contamination, applying wound sealants where appropriate, and removing deadwood from the orchard to eliminate potential inoculum sources.