What can I do about sap leaking out of cherry tree?

Asked September 23, 2013, 10:23 PM EDT

I have a cherry tree in my yard and there is a brown sap leaking from where the branches meet the trunk. I don't see anything leaking anywhere else. Is that normal? If not, what can I do about it? I am attaching a photo.

Wayne County Michigan

1 Response

Gum and bleeding is a result of a break in the bark of the tree and, there are a lot of different things that can break through the bark. The injury can be due to freeze damage (in this case the sap shows up in the early summer), or from insects or mechanical damage.

There are three groups of organisms that can cause cankers on cherries and result in a gummosis response.
· One is a bacteria in the genus Pseudomonas which causes a disease known as bacterial canker.
· Another is a fungus in the genus Leucostoma (Cytospora) that causes Leucostoma canker of Prunus.
· The third is usually called fungal gummosis and is caused by the fungus Botryosphaeria dothidea.

It is not important in a practical sense to identify the specific organisms involved but, it is important from a diagnostic point of view to differentiate between insect infestation, mechanical injury, and infectious disease. In all three of the diseases listed above, the key diagnostic feature is the canker.

A canker is a necrotic (dead), often sunken lesion on a stem, branch, or twig of a plant. In the case of gum bleeding from the trunk of a cherry tree, a canker can be identified by the death of tissue immediately beneath and surrounding the point of gummosis. If you carefully scrape away the gum and probe the bark beneath, you will find the bark loose and the tissue beneath discolored. In fact, the bark at the point of gummosis may slough off easily indicating dead tissue. Clean the gum away with a sterile knife but do not dig too deeply, then treat with a copper fungicide, available at most lawn and garden stores. Read and follow label instructions.

You may find these website of interest: http://www.walterreeves.com/landscaping/bleeding-cherry-tree-gum-on-bark/ http://aces.nmsu.edu/ces/yard/2001/101301.html

Keep the tree well watered, watering once a month through the winter, then see how it looks in the spring. It may recover if there is physical damage which is not too extensive.

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