White bark rot

The fungus Marasmiellus albus-corticis is identified as the causal agent of white bark rot. This pathogen specifically targets the bark and cambium layers of woody plants, leading to tissue necrosis and the progressive destruction of the tree's protective layers.

This disease primarily affects various species of fruit-bearing trees. The fungus typically gains entry into the host plant through wounds, frost cracks, or improper pruning cuts. Once established, the mycelium spreads underneath the bark, gradually colonizing larger areas of the trunk and limbs.

Visual symptoms include the formation of distinct white fungal mats or rhizomorphs on the bark surface. As the infection advances, the bark becomes brittle and may start to peel away, revealing underlying wood that shows signs of decay, which eventually stunts the tree's development and causes branch dieback.

The development and spread of Marasmiellus albus-corticis are highly dependent on high humidity and mild temperatures. Spores are easily disseminated by wind, rain splashes, or contaminated pruning equipment, making strict sanitation practices essential to prevent the spread within an orchard.

The economic impact of this disease is significant, as it threatens the long-term productivity and survival of orchard trees. If left untreated, the fungal colony can girdle branches or the main trunk, leading to the eventual death of the affected plant parts.

• Implement strict sanitation by removing and burning all infected bark and wood.
• Disinfect pruning tools with alcohol or bleach between each tree.
• Apply wound dressings to all cuts to prevent fungal colonization.
• Maintain optimal tree vigor through balanced fertilization and proper irrigation.
• Use preventative fungicide treatments in early spring to protect susceptible trees.