Bacterial wetwood

Bacterial wetwood, also known as "slime flux," is a chronic disease of tree trunks caused by the bacterium Enterobacter nimipressuralis. This pathogen infiltrates the inner wood, specifically targeting the heartwood and sapwood, where it thrives and causes systemic damage to the tree's health.

The primary hosts for this infection are various species of Elm, although it can affect other hardwoods. The disease is characterized by the internal fermentation of wood tissues, which results in the production of gases that create significant pressure within the trunk.

The most distinctive symptom is the fluxing of a foul-smelling liquid from cracks in the bark or pruning wounds. This exudate often leaves dark, vertical streaks on the bark as it runs down the trunk. Infected trees may exhibit leaf yellowing, thinning canopy, and overall decline, as the bacterial activity interferes with water and nutrient transport.

Environmental factors such as high soil moisture, root stress, and physical wounds on the trunk facilitate the entry and spread of the pathogen. Once established, the wetwood condition persists, as the bacteria continuously utilize the tree's carbohydrates, weakening the tree's structure over several growing seasons.

• Avoid unnecessary pruning or trunk wounding.
• Provide optimal tree care to reduce environmental stress.
• Properly disinfect pruning tools between cuts.
• Remove severely infected branches if necessary to manage structural integrity.

There is currently no cure for bacterial wetwood. Management strategies focus on preserving the vigor of the tree and minimizing entry points for the bacteria. Regular inspections of high-value trees are essential to identify the early signs of flux and to monitor the long-term impact on tree stability.