Bacterial canker of poplar

Xanthomonas populina is a pathogenic bacterium responsible for causing bacterial canker, a devastating disease of poplar trees. This infection targets the tree's vascular tissue and cambium layer, causing serious structural damage and disrupting the vital transport of nutrients throughout the plant.

The primary hosts of this pathogen are various species and cultivars within the Populus genus. The disease poses a significant threat to commercial nurseries and plantations, as young and rapidly growing trees are particularly susceptible to infection, often leading to stunted growth or premature mortality.

Symptoms typically manifest as lesions on the bark, which evolve into persistent open cankers. Notable signs of the disease include:

• Development of sunken or raised necrotic spots on the main trunk.
• Exudation of bacterial ooze from the affected bark tissues.
• Cracking of the outer bark, exposing internal wood to decay.
• Dieback of branches or wilting of the entire canopy in severe cases.

Environmental conditions play a crucial role in the dissemination of Xanthomonas populina. High humidity and rainfall facilitate the spread of the bacteria via water splash, while contaminated pruning tools and wood-boring insects act as major vectors. Once the pathogen gains entry through bark fissures or wounds, it colonizes the cambium, creating favorable conditions for disease progression.

The economic impact of bacterial canker is significant, as it reduces timber quality and can destroy entire plantation stands. Effective management requires a combination of strict phytosanitary measures, including the removal of infected trees, the selection of resistant poplar genotypes, and the sterilization of pruning equipment to prevent cross-contamination across the site.