Diatrype necrosis

Diatrype necrosis is a widespread fungal disease affecting various broad-leaved trees and woody ornamental plants. The pathogen, belonging to the genus Diatrype (such as Diatrype stigma), acts primarily as a saprophyte that can turn into a weak parasite, aggressively attacking trees that are already stressed or damaged.

The host range is quite broad, including species such as oak, beech, birch, and various pomaceous fruit trees. The infection typically establishes itself through wounds in the bark caused by pruning, mechanical damage, or extreme weather conditions like frost cracks, which provide an easy entry point for fungal spores.

Visible symptoms include the appearance of sunken or depressed areas on the bark. As the mycelium grows, it forces the production of stromatic fruiting bodies, which appear as tiny black pustules breaking through the outer surface of the bark. This activity disrupts the flow of nutrients and moisture within the wood, leading to dieback of branches and, eventually, death of the tree.

Environmental conditions play a crucial role in the development and spread of the disease. High humidity and poor air circulation within the canopy create ideal conditions for spore germination and colonization. Spores are primarily dispersed by wind and rain splashing, facilitating the rapid spread of the fungus throughout the stand or orchard.

Effective management and prevention are centered on strict phytosanitary practices. Key strategies include:

• Regular pruning to remove symptomatic branches
• Disinfecting cutting tools to prevent cross-contamination
• Applying protective paints to large pruning wounds
• Improving tree vigor through proper irrigation and fertilization