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Gummy Gummosis

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Have you noticed the oozing of a gummy substance from the branches and trunks of some trees in your local area? This fascinating natural process is known as gummosis and it can form on the surface of certain plants, especially stone fruit trees (plums, peaches, nectarines, and cherries.)

Gummosis will occur when the tree or plant is under some kind of stress. Who knew that trees could get stressed too?

Gummosis is not a disease and is, in fact, most often associated with cankers, which are sunken lesions on trunks, branches, or twigs. These cankers can be caused by physical injuries (e.g. pruning), insects, winter damage, sunscald, chemical injury, and different fungal or bacterial infections. In response to these stresses or injuries, a sticky, amber-coloured ooze or “gum” flows out from these lesions.

If the damage or infections are severe, you might see some wilted leaves or even the eventual death of the fruit-bearing wood. However, it is not the presence of gummosis itself that will cause the tree or plant to die, but rather the stresses or injuries. Gummosis is more like the indicator!

Much of the gummosis that we notice around here occurs on High Park’s different species of cherry trees: Black Cherry, Pin Cherry, and Chokecherry.

Keep an eye out for gummosis on your next visit to High Park!

If you would like to learn more about the world of trees, check out our “Tree-mendous Trees” Online Naturalist Course for adults!