Dothiorella necrosis

Dothiorella necrosis, caused by fungi of the genus Dothiorella, is a serious plant disease characterized by tissue dieback and vascular system impairment. This fungal pathogen targets the woody parts of various trees, severely disrupting the translocation of essential nutrients and moisture throughout the plant.

The disease affects a wide range of host plants, most notably tropical and subtropical species such as Indian mango, avocado, and various ornamental trees. It thrives in plantations where humidity levels are high and the trees lack proper structural maintenance or are susceptible to environmental stressors.

The clinical signs include the development of darkened, sunken lesions on the branches and trunk. As the necrosis advances, the bark may peel or crack, and dark streaks can be observed within the wood when examined cross-sectionally. Over time, the affected branches exhibit chlorosis, premature leaf drop, and sudden wilting.

Environmental conditions such as high temperatures combined with prolonged leaf wetness are critical for the proliferation of the pathogen. The fungus survives in dead or dormant wood, producing pycnidia that release spores during rainfall, which are then disseminated by water splash or wind to neighboring trees.

The economic impact of Dothiorella necrosis can be significant, leading to reduced fruit yields and, in severe cases, the complete collapse of canopy limbs. Implementing a robust prevention program is essential for nursery and orchard management:

• Sanitize pruning equipment regularly with alcohol or bleach solutions.
• Promptly remove and dispose of infected limbs at least 15-20 cm below the visible necrosis.
• Apply protective copper-based fungicides after pruning to seal wounds.
• Improve air circulation within the orchard to reduce local humidity levels.