Athelopsis galzinii

The primary symptom is the appearance of a thin, whitish to grayish film on the bark, which may look like a dried crust or a fine web covering the surface.

Affected bark loses its natural flexibility, develops cracks, and often starts to peel away from the wood beneath. The tissue underneath the fungal layer may show discoloration.

Visible dieback of individual branches is a common symptom. The decline usually begins at the ends of branches and progresses toward the main trunk.

In cases of advanced infection, necrotic lesions or small cankers may develop, leading to the formation of open wounds or localized decay of the wood.

The foliage on affected branches may turn yellow or wilt prematurely due to the restricted transport of water and nutrients caused by the fungal damage to the vascular tissue.

The causal agent is the fungus Athelopsis galzinii, belonging to the Atheliaceae family within the order Corticiales. It is a basidiomycete fungus that typically functions as a saprotroph or a weak parasite on woody tissues.

The fungus produces a thin, effused, and often crust-like or web-like hymenophore on the surface of wood or bark. It typically appears white to cream-colored and adheres tightly to the substrate.

Microscopically, it is identified by its specific basidia and spore morphology. It lives by penetrating and decomposing structural components of wood such as cellulose and lignin.

It is widespread in nature, often appearing on fallen branches or decaying stumps, but can opportunistically colonize stressed or damaged living trees.

The life cycle involves vegetative mycelial growth followed by sporulation during periods of high humidity, allowing for the dispersal of spores via wind or water splashes.

High humidity and moisture are the most critical factors for the development and spread of Athelopsis galzinii. Prolonged rainfall or heavy fog creates the ideal environment.

Poor aeration in dense, unpruned canopies traps moisture, providing perfect conditions for the fungus to establish itself and proliferate on bark.

Mechanical injuries resulting from pruning, storms, or insect damage act as entry points for the pathogen, allowing it to colonize deeper wood layers.

Trees weakened by drought, nutrient deficiencies, or other stressors are significantly more susceptible to infection compared to healthy, vigorous plants.

The fungus is most active during the spring and autumn seasons when temperatures remain moderate and moisture levels are typically elevated.

The primary harm is the destruction of the bark and cambium, which disrupts the transport of water and nutrients, leading to the gradual decline of the tree.

Persistent infection results in branch death and loss of structural integrity, eventually rendering the tree unproductive or causing its premature death.

The weakened wood is highly susceptible to secondary infestation by wood-boring insects, which accelerates the decomposition process significantly.

The fungus serves as a source of inoculum, with spores easily spreading to neighboring trees in the orchard, leading to widespread infection if not managed.

Economic losses include increased maintenance costs, the necessity for tree removal, and reduced fruit yields due to the compromised health of the host.

Sanitation is the most effective control method. Promptly remove and dispose of all dead or heavily infected branches to reduce the amount of inoculum.

All pruning wounds should be treated with appropriate wound dressings or protective paints to prevent fungal spores from entering the fresh wood.

Whitewashing trunks and major branches with a lime-based mixture containing copper-based fungicides can create a barrier against fungal colonization.

Promote good airflow by thinning the tree canopy. Regular fertilization and watering help maintain tree vigor and improve natural resistance to pathogens.

In severe cases, targeted fungicide applications during the dormant season or early spring can help control fungal activity and prevent further spread.