Dothiorella dieback

The fungus Dothiorella dominicana (anamorph of Spencermartinsia dominicana) is a significant plant pathogen responsible for dieback and canker diseases in a variety of woody plants. As a member of the Botryosphaeriaceae family, it invades the vascular tissues and bark, causing systemic disruption of nutrient and water flow, which ultimately leads to the decline and death of branches or entire trees.

This pathogen has a broad host range, notably affecting fruit-bearing species like mango, avocado, and various citrus varieties. It is also documented in several deciduous trees and woody shrubs. The disease usually enters the plant through natural openings, pruning wounds, or sites of mechanical damage, establishing itself in the wood and slowly expanding its range during the dormant and growing seasons.

Infected trees typically display signs of bark necrosis, which appears as sunken, dark lesions on the stems or main branches. As the infection progresses, the leaves distal to the site of infection begin to wilt and turn yellow or brown. A key identifying feature is the presence of internal vascular discoloration in the affected branches, often described as brownish staining under the bark layer.

The disease thrives under high humidity and fluctuating temperatures, which stress the host plant and facilitate fungal sporulation. Rain and wind act as the primary vectors for dispersing spores within the orchard. Once established, the fungus can remain dormant within the xylem of branches for long periods before becoming active, making it difficult to detect in the early stages of infestation.

Proactive management is critical to prevent the spread of Dothiorella dominicana across an orchard. Key control strategies include:

• Rigorous sanitation practices, including the removal of all dead or dying wood.
• Sterilization of pruning tools using 70% alcohol or bleach between individual trees.
• Application of protective fungicides on fresh cuts to seal wounds against airborne spores.
• Optimization of orchard irrigation and fertilization to minimize stress-induced susceptibility.
• Regular monitoring and rapid identification of early necrosis to prevent systemic spread.