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Bacterial Wetwood

Bacterial WetwoodBacterial Wetwood, also known as bacterial slime, is a common disease that can affect the bark and core of many shade and forest trees. This disease can affect a wide variety of trees ranging from oak and maple trees to fruit trees – such as apple, cherry, plum trees.

Common Symptoms

Common symptoms of bacterial Wetwood include a yellow-brown discoloration of the wood, usually confined to the central core of the tree, and a foul smelling, oozing slime which is colonized by yeast organisms when exposed to the air. The slime can dry into a light gray-ish, white crust. This coloration distinguishes bacterial wetwood from insect borer damage which produces an orange shinny ooze. Often times, the ooze will draw the attention of insects such as sap beetles and flies. However, since there is no evidence that these insects can transmit the disease, the presence of beetles or flies is not a cause for concern. The scientific consensus is that bacterial wetwood is usually transmitted through the soil and water where bacteria commonly associated with wetwood exists.


Unfortunately, no effective methods have been found to eliminate Wetwood disease that has already developed. However, there are ways to prevent the development of a wetwood problem. The best way to avoid a serious wetwood problem is to prevent damage and stress to the tree’s roots and stem. This can be done by maintaining the trees water and nutrient levels properly and avoiding traumatic events such as serious root removal or transplanting. The amount of water the tree receives is vital during droughts and can cause root stress. For example, if a tree has been recently transplanted it can ooze slime if the roots are not established and the tree isn’t getting enough water. In such a case, fertilization is the recommended approach.

Drain tubes have been used to release ooze from the infected trees but this practice is not recommended as it introduces more oxygen into the trees system and can allow for wood decay.


If Bacterial Wetwood has developed then it is recommended that the home owner contact an arborist for a consultation. More often than not, the wetwood compromises the structural integrity of the tree and the tree must be removed because it has become a safety liability. This was the case with the tree found in the picture above. The wetwood had compromised the ability of that stem to bear the weight of the branches and unfortunately had to be removed. You will notice that the coloration of the bacteria is dark and has not crusted over to a grey or white color. This is generally a sign that the infected area is still wet and is in the middle stages of wetwood development.