Chrysoporthe canker of eucalyptus

The causative agent of this disease is the fungus Chrysoporthe puriensis, an ascomycete known to cause severe stem cankers in plantation-grown trees. This pathogen invades the vascular cambium and bark, effectively girdling the tree and causing significant physiological stress.

The disease primarily impacts various species of the genus Eucalyptus. It is a critical concern for commercial forestry operations, where the environmental conditions and host uniformity can facilitate the rapid spread of the fungus throughout entire plantations.

Symptomatology includes the formation of discolored, sunken areas on the stem bark, which eventually crack and develop into open, perennial cankers. These lesions often exhibit gum exudation (gummosis), and progressive infection leads to canopy dieback, yellowing of leaves, and reduced tree vigor.

The development of Chrysoporthe puriensis is strongly correlated with high humidity and favorable temperature ranges. The fungal spores are dispersed by wind, rain splashes, and insect vectors. The presence of physical wounds on the tree trunk serves as the primary infection court for the pathogen to enter the host.

The pathogenicity of this fungus poses a major threat to timber quality and stand survival. Strategic management and preventative practices are essential to mitigate the impact of the disease:

• Selection and deployment of resistant or tolerant eucalyptus genotypes.
• Rigorous sanitation practices, including the removal of infected or dead trees.
• Management of plantation density to reduce microclimate humidity around the stems.
• Control of bark-boring insects that create potential entry points for the fungus.