Dothiorella necrosis

Dothiorella necrosis, caused by the fungus Dothiorella ribis (often associated with Botryosphaeria species), is a destructive plant disease that compromises the vascular system of trees and shrubs. By colonizing the woody tissue, the fungus inhibits the flow of water and nutrients, eventually leading to dieback.

The host range of this pathogen is extensive, encompassing many woody perennial plants. It is particularly problematic in vineyards, apple orchards, and various small fruit crops like currants. In recent years, it has been recognized as a significant constraint on the longevity of commercial woody crops.

Key symptoms include the development of cankers on branches and trunks, often accompanied by bark cracking. On a cross-section of an infected branch, one can observe distinct dark, wedge-shaped necrotic lesions in the sapwood. Under humid conditions, small, black, pin-head-sized fruiting bodies erupt through the bark surface.

The development of the disease is closely linked to environmental stress. Drought, frost damage, and poor horticultural practices weaken the host, making it susceptible to fungal entry through pruning wounds, insect feeding sites, or natural fissures in the bark. Moist, warm weather conditions facilitate the production and spread of spores.

The economic impact of Dothiorella necrosis is substantial, as it causes reduced yield, decreased fruit quality, and the eventual death of branches or entire plants. Managing the disease is challenging because the fungus can survive in dead tissue for long periods, acting as a constant reservoir of inoculum within the orchard.

• Sanitary pruning of all symptomatic wood during the dormant season.
• Disinfecting pruning shears between cuts to prevent cross-contamination.
• Applying protective pruning sealants to large cuts to minimize entry points.
• Maintaining vigorous plant growth through balanced fertilization and irrigation.
• Regular monitoring and removal of dead or declining branches from the canopy.