acer bloodgood appears to have a disease

Question

I have a four year old acer bloodgood that appears to have a disease on the trunk. It’s in a small front garden and has been fine until now.

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Answer 1

It does appear to be a canker. Treatment of cankers is more about prevention.
A mild case will resolve itself.

Here is a couple of links.
https://www.gardeningknowhow.com/ornamental/trees/japanese-maple/japanese-maple-problems.htm
https://www.gardeningknowhow.com/ornamental/trees/maple/maple-tree-bark-disease.htm

http://www.plantpath.ksu.edu/doc944.ashx