Cytospora canker

Systematic position: Cytospora chrysosperma is an ascomycete fungus belonging to the order Diaporthales. This pathogen is globally recognized as the causative agent of Cytospora canker, a destructive disease that leads to the systemic necrosis of the bark of various woody plants.

Diseases and host plants: The fungus primarily affects trees and shrubs such as poplars, willows, apple, and pear trees. It causes canker development, leading to girdling of branches and trunks. Once the bark is girdled, the distal parts of the tree die, significantly compromising the plant's health and structural integrity.

Biology and life cycle: The pathogen reproduces via conidia, which are produced in pycnidia. Under moist conditions, these conidia are exuded in characteristic yellow to orange-colored cirri. The fungus overwintering as mycelium in the infected bark tissue, allowing it to initiate new infections during the early spring when environmental conditions become conducive for growth.

Conditions for development and harmfulness: Development is highly correlated with tree stress factors, including drought, mechanical injury, frost damage, or improper pruning. The harmfulness is severe, as the infection blocks the vascular transport system of the plant, often leading to total tree failure if the main stem is compromised by large cankers.

Management and control: Managing Cytospora chrysosperma requires an integrated approach focusing on tree vitality and sanitation:

• Removal and immediate destruction of infected branches during dry weather.
• Sterilization of pruning tools to prevent the mechanical spread of spores.
• Proper irrigation and fertilization to minimize physiological tree stress.
• Applying wound dressings or fungicides to exposed wood to prevent new fungal colonization.