Pertusariales fungi

The order Pertusariales comprises a diverse group of Ascomycota fungi, which are predominantly lichenized. In agricultural practice, they are often observed as epiphytic growths on tree trunks and branches. While not always classified as a primary pathogen, their unchecked proliferation can lead to significant physiological stress for fruit and ornamental trees.

The causal agents are specialized fungal species that colonize the outer bark. By forming dense crustose thalli, these fungi alter the microclimate on the surface of the trunk, which can inadvertently create a reservoir for secondary pests and opportunistic pathogens that do cause severe tree damage.

These organisms primarily affect woody perennial plants. Orchards with neglected trees, elderly apple or pear trees, and shaded garden areas are particularly susceptible. The structural integrity of the bark plays a major role in determining the severity of the colonization by these fungal groups.

Symptoms include the appearance of grey, white, or yellowish patches, as well as small, disk-like fruiting bodies known as apothecia. Persistent presence of these colonies may lead to surface necrosis of the bark, inhibited photosynthesis if the growth covers young stems, and premature cracking of the woody tissues.

Effective management focuses on creating unfavorable conditions for fungal growth. Improving air circulation within the tree canopy is essential to reduce humidity levels. Additionally, mechanical cleaning of the bark during the dormant season and the application of protective coatings significantly decrease the prevalence of Pertusariales in agricultural systems.