Maple tree disease


Hi Master Gardener,
I have attached a photo of my maple tree. It seems that it has some disease. Would you please let me know how it can be treated? Thanks a lot


Thanks for contacting Toronto Master Gardeners.  Based on your photograph, it looks like your tree may have some type of canker.  Cankers are caused by fungi and trees are more susceptible when they receive inadequate nutrients and water, are planted in poor soil conditions,are inappropriately pruned or the bark receives a wound. The progression of the disease is dependent on the type of fungus.  To get a definitive diagnosis it is best to consult an arborist.  It is possible that the tree will be need to be removed.  Often trees that have cankers become hazards because they decay internally and become structurally unsound.  For more information please see:

You haven’t mentioned the type of maple you have but if it is a sugar maple, it is also possible that it has sapstreak disease.  Sapstreak is a ground-living fungus that moves upwards from the root system and infects the trunk of the tree. Sometimes it resolves on its own but it can also kill the tree.  For more information please see: