Diplodia fig canker

Pathogen and disease type. The disease known as Diplodia fig canker is caused by the fungus Diplodia caricae. This pathogen belongs to the Ascomycota division and is a specialized agent that affects the woody tissues of fig trees. It is classified as a necrosis-inducing fungus, where the mycelium colonizes the bark and cambium layers, disrupting the tree's vascular system and leading to severe tissue damage.

Susceptible crops. The primary host for this fungus is the common fig (Ficus carica). While the pathogen is relatively host-specific, it can be found in various cultivars of fig trees planted in humid subtropical and Mediterranean climates. It typically impacts mature branches, stems, and occasionally fruit, causing significant damage to the structural integrity of the plant.

Symptoms and signs. The characteristic symptoms begin as small, dark, sunken lesions on the bark of branches or the main trunk. As the disease advances, these lesions expand and may form a girdle around the stem, causing the leaves and fruit above the affected area to wilt, yellow, and die. Small black, spore-producing structures known as pycnidia often become visible on the surface of the dead bark.

Development and impact. The development of the disease is highly favored by high humidity, prolonged rainy periods, and warm temperatures. These conditions stimulate the production and dispersal of spores. The pathogen often gains entry into the host through pruning wounds, frost cracks, or other mechanical injuries. The economic impact is significant, as the disease leads to branch dieback, reduced fruit yield, and potential mortality of the entire tree.

Management and prevention. Controlling the disease requires an integrated approach focusing on sanitation and hygiene:

• Regular pruning of infected branches, ensuring cuts are made well below the necrotic tissue.
• Immediate removal and burning of all prunings to prevent spore accumulation.
• Sterilization of pruning tools using alcohol or bleach solutions between trees.
• Application of wound dressings to large cuts to prevent new infections.
• Preventive applications of copper-based fungicides during the dormant season and early spring.