Diaporthe bark dieback

Diaporthe decorticans is a fungal pathogen responsible for bark necrosis and stem dieback in various woody plant species. As an ascomycete fungus, it primarily acts as a facultative parasite, exploiting weaknesses in tree tissue caused by environmental stress, mechanical damage, or improper pruning practices.

The disease frequently targets fruit-bearing trees, such as apple and pear, though it can also affect various ornamental species. By invading the cortical tissues, the fungus disrupts the transport of nutrients and water, eventually leading to the death of affected branches and potentially causing systemic decline in severe cases.

Symptoms typically manifest as sunken, discolored patches on the bark that crack and peel over time. Within these necrotic areas, small, dark fruiting bodies of the fungus (pycnidia or perithecia) can often be seen erupting through the bark surface, signaling an active sporulation stage.

Development of the fungus is highly favored by high humidity and prolonged periods of wet weather. Spores are primarily dispersed through splashing raindrops and wind, although the movement of contaminated pruning equipment is a major factor in the spread of the pathogen within an orchard or garden setting.

Managing Diaporthe dieback requires a proactive approach centered on sanitation and environmental control. Growers should prioritize the prompt removal of infected wood, ensure that all cuts are clean and treated, and maintain tree vigor through balanced nutrition. Chemical intervention, particularly preventive sprays with copper-based products during the dormant season, is highly recommended.