Poplar bacterial necrosis

The disease known as poplar bacterial necrosis is caused by the bacterium Lonsdalea populi. This pathogen belongs to the Pectobacteriaceae family and is recognized as a significant threat to various Populus species, specifically impacting the health and longevity of poplar plantations globally.

The primary hosts for this bacterium are different species and hybrids of poplar trees, such as Populus × euramericana. The infection is particularly devastating in nursery settings, where it can spread rapidly among young seedlings, as well as in established forestry plantations and urban green spaces.

Symptoms of Lonsdalea populi include the development of bark necroses, often accompanied by exudation of bacterial fluid. Over time, these areas crack, forming deep cankers or lesions that expose the underlying wood. Internal wood tissues often exhibit dark staining, reflecting the obstruction of vascular bundles caused by the bacterial colonization.

Environmental conditions that favor the disease include high humidity, moderate temperatures, and frequent rainfall. The bacterium enters the host primarily through entry points like frost cracks, pruning wounds, or lenticels. Once inside, the systemic spread occurs through the xylem, severely restricting the tree's ability to transport water and nutrients.

The impact of this disease is severe, leading to branch dieback and ultimately the mortality of the host tree. To manage the pathogen and minimize losses, arborists and foresters should implement the following strategies:

• Sanitary pruning and removal of infected branches or entire trees to reduce inoculum pressure.
• Strict sanitation of all pruning tools using appropriate disinfecting agents.
• Avoidance of mechanical damage to tree trunks to prevent bacterial entry.
• Selecting and planting resistant poplar cultivars or clones.
• Maintaining proper spacing and air circulation in nurseries to prevent moisture buildup on bark surfaces.