The most common cause of this problem is an infection caused by several species of bacteria including Enterobacter, Klebsiella and Pseudomonas. The infection causes a buildup of pressure from fermented sap that pushes out of cracks in the bark. It is a chronic disease which may be with the tree for decades.

In the spring, a slimy, sour smelling ooze seeps from the bark of certain trees. Later, the ooze dries and forms a permanent, gray colored stain on the bark of the tree. Members of the Elm (Ulmus) genus are probably the most common trees to be infected by wetwood. In fact, one of the identifying features of elms is that you can see the gray bark stain leading down from the crotch of the tree from a distance.

The only way to prevent this problem is to avoid growing susceptible plants.
 

There are no chemical controls for this condition. To relieve some of the internal pressure, some arborists will bore a small hole in the bark on an upward direction toward the seeping area. They will insert a 1/2 inch diameter copper or plastic tube into the hole to carry the ooze away from the bark. Of course, since you are dealing with a bacterial infection, all tools should be disinfected with alcohol before using them on another plant.

 
Members of the Elm (Ulmus) genus are probably the most common trees to be infected by wetwood.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

 

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