Bacterial wetwood, commonly known as slime flux, is a prevalent plant pathology resulting from bacterial activity inside a tree’s trunk or branch. Anaerobic bacteria ferment the tree’s internal sap, generating high gas pressure that forces liquid to ooze out through wounds. This article evaluates the potential hazards of slime flux to people and provides practical guidance for managing affected trees.
Identifying Slime Flux
Slime flux is recognized by a watery, slimy, or frothy ooze that bleeds from cracks, pruning cuts, or other openings in the bark. This exudate can appear gray, brown, or streaked with white, eventually running down the trunk and leaving a noticeable discolored stain. As the liquid drains, it often dries into a light gray or white crust on the tree’s surface.
The most distinctive characteristic for confirming the presence of slime flux is the strong, unpleasant odor it produces. This foul smell results directly from the anaerobic fermentation process within the tree’s wood, which generates gases like methane and nitrogen. The smell is frequently described as rancid, sour, or vinegary, caused by the byproducts of bacterial action on the sap.
Human Health Risks Associated with Slime Flux
Slime flux poses a very low direct threat to human health, as the bacteria involved are typically plant-specific and soil-dwelling organisms. The primary organisms, such as certain species of Enterobacter, Klebsiella, and Pseudomonas, are common in soil and water environments. Although some species within these bacterial genera are known human pathogens, the specific strains active in slime flux generally do not cause illness in people.
The fermented sap is toxic to the tree’s cambium tissue and can kill grass or other herbaceous plants it drips onto. However, it is not considered toxic to human skin upon incidental contact, as the liquid is simply fermented tree sap. The main risks to people are indirect or environmental, rather than directly pathogenic.
Indirect Risks
The most common indirect risk is the attraction of nuisance insects to the sweet, fermenting liquid. The ooze attracts various flies, sap beetles, and stinging insects like wasps and bees, which feed on the sugary residue. This concentration of pests near the tree presents a heightened environmental risk, especially for individuals with insect sting allergies. Additionally, if the slimy liquid drips onto paved surfaces, it can create a slick area, posing a slip-and-fall hazard.
Safe Management of Affected Trees
Since the direct health risk is minimal, management focuses on sanitation and promoting the tree’s natural healing process. Homeowners should clean up the ooze on the ground or pavement to eliminate the slip hazard and discourage insect activity. Washing the area with water helps remove the residue, though the tree will continue to weep until the internal pressure subsides.
It is recommended to avoid applying any wound dressing or sealant to the affected area. Sealing the wound traps the liquid and gas inside, which worsens the internal pressure and inhibits the tree’s ability to drain naturally. The best course of action is to allow the wound to drain freely and dry out, enabling the tree to compartmentalize the damage over time.
A proactive approach involves maintaining the tree’s vigor, as stressed trees are more susceptible to the condition. Ensuring adequate watering during dry periods and protecting the trunk from mechanical injuries are beneficial management practices. Avoiding unnecessary pruning and following proper techniques will limit the entry points for the responsible bacteria.