Cypress canker

Cypress canker is a devastating fungal disease caused by the pathogen Seiridium cardinale. It manifests as a necrosis of the bark and cambium, severely affecting the vascular system of trees and often resulting in the death of individual branches or the entire plant.

The primary hosts of this fungus are various species within the Cupressaceae family, including the genera Cupressus, Chamaecyparis, Juniperus, and Thuja. Among these, the Monterey cypress (Cupressus macrocarpa) is particularly susceptible to the infection, which has caused significant damage in various regions worldwide.

The disease is characterized by the appearance of sunken lesions on stems and branches, which are typically accompanied by excessive resin exudation (cankers). As the pathogen progresses, the bark cracks and peels, while the foliage beyond the infection point turns yellow, then brown, and eventually dries out, leading to canopy dieback.

The spores of Seiridium cardinale are primarily disseminated by wind, rain splashes, and human activity. Infection occurs through natural wounds or pruning cuts, particularly in warm and humid climates which favor the growth and reproduction of the fungus throughout the year.

Management of cypress canker relies heavily on rigorous sanitation practices. This includes the pruning and destruction of infected wood, thorough sterilization of tools after every cut to prevent cross-contamination, and the application of protective copper-based fungicides on high-value specimens to limit spore germination.