Deuterophoma

Deuterophoma is a genus of fungi responsible for serious vascular diseases in various plant species, most notably in citrus, where it causes conditions such as mal secco. The pathogen specifically targets the vascular tissue, or xylem, severely impairing the hydraulic conductivity of the plant and leading to a rapid decline in overall health.

The disease primarily affects woody crops, particularly in subtropical regions where environmental conditions favor the pathogen's development. It colonizes the internal tissues of the host, meaning that symptoms often remain internal until the damage to the vascular system becomes irreversible, leading to outward signs of distress and necrosis.

Key symptoms include chlorosis and wilting of the foliage, followed by leaf drop. A definitive diagnostic feature is the internal discoloration of the wood in the branches and trunk, which typically appears as a distinct reddish or reddish-brown hue. As the infection progresses, large sections of the canopy may die back, often resulting in total plant mortality.

Environmental conditions such as high humidity and moderate temperatures are critical for the dissemination of spores. These spores are spread through rain splashes, wind currents, and mechanical tools used during agricultural operations. Any breach in the bark or unprotected pruning wounds provides a gateway for the pathogen to enter the plant.

Effective management focuses on preventive measures rather than curative treatments. Once the fungus is systemic, it is extremely difficult to eliminate. Therefore, emphasis is placed on strict sanitation protocols, the use of disease-resistant varieties, and the application of copper-based fungicides to protect vulnerable entry points after pruning.

• Strict sterilization of pruning equipment between trees.
• Sanitary pruning of all symptomatic wood.
• Protection of pruning wounds with sealing agents.
• Regular monitoring and removal of infected plants to limit spread.