Pezicula canker

Pezicula canker is a fungal disease caused by various species of the Pezicula genus, most notably Pezicula corticola and Pezicula malicorticis. As a necrotrophic pathogen, it primarily infects the bark and cambium layers of woody plants. The disease is recognized for causing localized tissue death, which often results in sunken lesions and structural weakness within the tree's vascular system.

The disease primarily impacts fruit-bearing trees, with apple and pear orchards being the most susceptible hosts. While healthy trees can exhibit some resistance, stressed or poorly maintained specimens are highly vulnerable to colonization. If left unmanaged, the canker can expand, leading to the girdling of limbs and eventually the death of the affected branch or the entire tree.

The primary clinical signs of the disease include the formation of irregular, depressed lesions on the bark. As the fungus progresses, the area may become cracked and dry, exposing the wood underneath. During periods of high humidity, small, disk-shaped fruiting bodies (apothecia) appear on the surface of the bark, which serve as the primary source of spore dispersal for the next infection cycle.

Environmental conditions play a critical role in the development and spread of Pezicula. Spores are primarily dispersed through rain splash and wind, entering the tree through pruning wounds, insect feeding sites, or frost-damaged tissue. The pathogen thrives in cool, wet climates, making autumn and spring the most dangerous times for new infections to establish themselves in the orchard.

Effective prevention and control rely on maintaining tree vigor and hygiene. Key management practices include:

• Pruning out infected branches well below the margin of the visible lesion.
• Disinfecting pruning tools to prevent cross-contamination between trees.
• Applying protective copper-based fungicide treatments during dormant and post-bloom periods.
• Promoting rapid healing of pruning wounds with appropriate protective sealants.