Apple antrodia

The primary sign of infestation is the emergence of characteristic fungal fruit bodies on the bark surface or near significant damage sites on the trunk and scaffold branches.

The inner wood of the affected tree gradually turns into a decayed, fibrous mass exhibiting signs of white rot. The wood loses structural strength, becomes lightweight, and crumbles easily under mechanical stress.

In the early stages, visual symptoms might remain hidden; however, careful inspection often reveals bark discoloration or localized depressed areas on the trunk.

Foliage on affected branches will eventually exhibit premature yellowing and dropping, indicating a disruption in the tree's vascular system.

• presence of fruit bodies on the trunk;
• loss of crown turgor;
• structural failure of the wood;
• formation of hollows inside the trunk.

The causative agent of this disease is the wood-decaying fungus Antrodia malicola, belonging to the Basidiomycota division. This pathogen primarily targets deciduous tree species, causing white rot of the wood.

The fungus acts as a saprotroph and a weak parasite, entering the plant tissues through mechanical bark damage, pruning cuts, or frost cracks. Deep within the wood, the mycelium grows actively, decomposing the lignin and cellulose structure.

The fungal fruit bodies are typically resupinate or effused-reflexed, often adhering tightly to the substrate. They possess a leathery or corky texture and are characterized by light, yellowish, or brownish tones.

The life cycle involves the production of basidiospores within the hymenophore, which are disseminated by wind or insects over significant distances, ensuring the rapid spread of infection in neglected orchards.

The biology of Antrodia malicola is well-documented as a typical polypore fungus, capable of maintaining viability for long periods within dead or weakened woody tissues.

The development of Antrodia malicola is favored by high humidity and frequent precipitation, which create an ideal environment for fungal spore germination.

A critical factor is the weakened state of the trees: aging orchards, trees with improper pruning techniques, or those suffering from sunscald are highly susceptible to infection.

The temperature optimum for mycelial growth is within the moderate range typical for apple-growing regions, allowing the fungus to remain active throughout the entire warm season.

Lack of sanitary pruning and the presence of unremoved dry branches within the orchard provide primary infection foci from which the fungus transitions to living tissues.

High planting density, which restricts airflow through the crown, further contributes to local humidity buildup and accelerates the dispersal of spores.

Apple antrodia causes significant economic losses by leading to the gradual decline of the tree and eventually reducing its productivity to zero.

The decomposition of wood leads to a loss of structural integrity, making trees hazardous during strong winds or heavy snow loads—the risk of trunk breakage is significantly increased.

The progressive death of the vascular system leads to nutrient and moisture deficits, causing fruits to become undersized and lose their commercial quality.

Infected trees act as reservoirs of infection for healthy plants in the orchard, leading to widespread mortality across entire blocks if left unmanaged.

Control of this pathogen is challenging because the mycelium penetrates deeply into the tree tissues, rendering localized treatment nearly impossible.

The foundation of effective protection is regular sanitary pruning, with the mandatory removal of all dead, diseased, or broken branches where fungi can establish themselves.

It is vital to protect all wounds and pruning cuts with orchard paint or specialized fungicidal sealants to prevent spores from entering fresh wood.

Timely whitewashing of trunks and main branches with lime helps protect the bark from sunscald and cracking, which are primary entry points for the pathogen.

If severe infestation is detected, it is recommended to grub out and destroy the infected tree, preferably by burning the wood away from the orchard.

Maintaining high horticultural standards, including balanced fertilization and proper irrigation, enhances the natural immunity of trees against wood-decaying fungi.