Dothiorella citricola

The causative agent of the disease is the fungus Dothiorella citricola. This pathogen is classified as a fungus that primarily targets the wood and twigs of woody plants. It operates as a weak parasite, often colonizing tissues that are already stressed or compromised by environmental factors or mechanical injuries.

The disease primarily affects various species within the Citrus genus, including lemons, oranges, and grapefruits. It is a persistent issue in both commercial orchards and residential gardens, particularly where trees are subjected to poor ventilation or high humidity levels that favor fungal growth.

The infection manifests through several distinct symptoms on the bark and woody parts of the tree:

• Formation of necrotic dark patches on stems and branches.
• Development of deep cankers that may lead to bark cracking.
• Exudation of gum (gummosis) from affected areas.
• Presence of small, black pycnidia (fruiting bodies) erupting through the bark surface.

Development and spread of Dothiorella citricola are strongly influenced by climate conditions, with high humidity and moderate temperatures being the primary drivers. The spores are typically dispersed by rain splash or wind currents. Entry points for the fungus usually include pruning wounds, frost cracks, or sunburn damage on the tree trunks and main branches.

Damage caused by this fungus can be significant, leading to the dieback of major limbs and, in severe cases, the death of the entire tree. Management strategies should focus on rigorous sanitation, such as removing infected wood well below the visible necrotic tissue, and ensuring that tools are disinfected. Preventive applications of copper-based fungicides are often recommended to protect trees during high-risk seasons.