Dothiora canker

Dothiora canker is a fungal disease caused by the pathogen Dothiora maculans. This fungus acts primarily as an opportunistic parasite, targeting the bark of various woody plants. It thrives on trees that are already stressed due to environmental factors, such as drought, poor soil quality, or mechanical injuries to the bark.

A wide range of deciduous trees is susceptible to this pathogen, with fruit trees being particularly affected in managed orchards. The fungus colonizes the cortex and phloem layers of the branches and stems. By disrupting the transport of nutrients and water, the disease can lead to the progressive dieback of infected limbs and, in severe cases, the death of the entire tree.

The visual symptoms of the infection often start as small, dark, pimple-like structures on the bark, which are the fruiting bodies of the fungus. As the infection progresses, the surrounding bark may show signs of discoloration, sunken necrotic areas, or longitudinal cracking. These signs are often mistaken for environmental damage, making early identification essential for effective management.

The spread of Dothiora maculans is highly dependent on humidity and temperature. Rainfall events act as the primary vehicle for spore dissemination, splashing the pathogen from infected bark onto fresh wounds or pruning sites. Poor air circulation within the canopy and excessively humid microclimates significantly increase the risk of rapid colonization and disease spread throughout the orchard.

Managing the disease requires a rigorous integrated pest management (IPM) approach. The most effective strategy is to maintain tree vigor through proper fertilization and pruning. If infection occurs, pruning out infected branches several centimeters below the visible lesion is crucial. Applying copper-based fungicides during the dormant season can help reduce the overwintering spore load and protect the tree from initial infections.