Pezicula bark canker

The disease is caused by the fungus Pezicula sporulosa, an ascomycete pathogen known for inducing necrotic lesions on the bark of woody plants. As a facultative parasite, this fungus often targets trees that have been compromised by environmental stressors, mechanical injuries, or insect damage, turning them into hosts for localized infection.

Pezicula sporulosa affects a variety of deciduous trees, with particular concern for species within the Rosaceae family. The pathogen colonizes the bark tissues, leading to the disruption of vascular functions. While it may appear as a minor issue initially, if left unmanaged, the infection can significantly weaken the structural integrity of the affected branches.

The primary clinical signs include depressed, darkened areas of the bark that eventually rupture, forming distinct cankers. These lesions are often surrounded by callus tissue in the early stages, but as the fungus spreads, the bark may peel away, revealing the damaged wood underneath. During wet weather, tiny, light-colored fruiting bodies emerge on the surface of the cankers, releasing spores for further dispersal.

Environmental conditions play a critical role in the development and spread of this disease. High humidity, frequent rainfall, and mild temperatures create the optimal environment for spore germination and colonization. The pathogen is primarily transmitted via splash dispersal from rain, wind currents, and potentially through contaminated pruning tools during routine garden maintenance.

Economic and physiological damage results from the girdling of branches, which blocks the flow of water and nutrients, ultimately causing branch dieback and reduced vigor. Effective management requires a combination of strict sanitation practices, such as removing infected wood, and the application of protective fungicide treatments. Maintaining tree health through proper fertilization and irrigation is also essential to prevent susceptibility to such fungal pathogens.