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Word of the Week: Gummosis

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Welcome to Word of the Week! Stay tuned for a new word each Friday to amp up your nature vocabulary!

Gummosis [guh-MOH-sis] (noun): The formation of patches of a gummy substance on the surface of certain plants, particularly 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 can 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. Over time, cankers can become more obvious, as branches swell or form corky growths on the margins.

If the damage or infections are really 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 stressor. 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 are looking to explore other Trees, check out our “ Sleeping Skeletons of High Park” Family Nature Walk, happening on Saturday, February 29! You’ll learn how to ID trees during their winter dormancy by studying their buds, twigs and bark.