Discostroma

Discostroma is a genus of ascomycete fungi that acts as a pathogen or saprotroph on various woody plants. This fungus is primarily known for causing bark necrosis, leading to branch dieback and systemic weakening of the host tree or shrub.

The disease is caused by the fungal agent colonizing the inner bark and cambium layers. As the infection progresses, it disrupts the flow of nutrients within the plant, which results in localized tissue death. The fungus survives unfavorable conditions as mycelium or ascostromata, remaining embedded in the diseased woody tissues throughout the winter season.

Typical hosts include a wide range of fruit-bearing trees and ornamental shrubs. Symptoms are characterized by bark discoloration, splitting, and the emergence of small, dark, raised structures known as stromata. These structures are essential for the production and release of fungal spores, which are disseminated by wind and rain splashes.

The development of Discostroma is heavily influenced by environmental moisture and the physiological state of the plant. High humidity and cool, damp weather accelerate spore production, while trees weakened by drought, frost damage, or improper pruning are significantly more susceptible to infection.

Effective management requires a multi-faceted approach. Preventive strategies involve maintaining tree vigor through proper fertilization and irrigation. If infection is detected, all affected branches must be pruned and removed from the site to minimize inoculum buildup. Applying copper-based fungicides during the dormant season is a standard practice to protect wounded or susceptible bark tissues.