The bark is coming away in some parts of the plum tree in my garden. In these areas there have been a lot of centipedes living there. Also, where one branch was cut off, there is a bubble of sap coming from the tree. From the attached picture, do you think this is a problem and how might it be corrected?
An old plum tree will normally have some flaky bark and this is not a problem. It looks like some branches might have been broken or cut away in the past. Gum often exudes from a pruing cut, but pruning should be minimised and only carried out in summer to reduce the risk of silver leaf disease, a fatal disease of plum trees. The tree seems fine, just a bit aged.