I have two cherry trees in my backyard. The eldest is quite large and is probably 40-50 years old but still healthy. The problem is that the younger one (maybe 10-15 years old) had developed gummosis. I’ve searched the web on treatments but everything I’ve found pertains only to the branches. In my case the gummosis appears at the base of the tree and therefore impossible to prune. It has also spread around the entire perimeter of the base so if I scrape off the unhealthy bark I’m afraid of girdling the tree.
Is there a way to treat it in this location or am I going to lose the tree?
Thank you for contacting Toronto Master Gardeners.
Gummosis, the oozing of sap from a diseased or damaged tree, is a plant’s reaction to stress. It is common in members of the Prunus species which includes cherry trees.
There are many possible causes of gummosis including mechanical injuries, environmental stress, insects, and disease.
Try to identify the source of the tree’s stress. Has the tree been injured mechanically, say by lawn or garden equipment? Is there evidence of insect attack? In these cases, sawdust or pieces of bark will be mixed in the sap.
If insect damage is evident, an arborist may be able to apply a pesticide to control the insects.
From your description, it is quite possible that your tree has succumbed to some type of cherry canker. This is a fungal or bacterial disease spread by spores which enter the tree through injured tissue and then germinate inside.
Unfortunately, there is no easy cure for such diseases.
Pruning out infected wood (during the dormant season) and good cultural practices (adequate water and nutrients, appropriate pruning, protection from winter injury) are typically recommended for such disease management.
If the entire trunk has been infected, your only option may be to remove the tree. This will also reduce the chance that your other tree succumbs to disease too.
I recommend that you contact a professional arborist regarding your next steps. Proper infection control measures during tree removal will be critical to the good health of your remaining tree.
You can find a certified arborist on the Landscape Ontario site: https://landscapeontario.com/ or on the International Society of Arboriculture (ISA) site https://www.treesaregood.org/findanarborist/findanarborist