The main symptoms are sunken, dead patches of bark and small holes in leaves. Cankers form in mid-spring, shotholes on foliage from early summer. They are often accompanied by a gummy ooze. If the infection spreads all around the branch it will die rapidly. However, it should be noted that gum production (gummosis) from the bark of Prunus species is actually quite common, and in the absence of dead, sunken bark, is likely to have resulted from causes other than bacterial canker, for example physical damage or environmental stresses.

Shoots may either fail to emerge, or start to grow normally in spring before dying back rapidly. In severe cases this may affect a large percentage of shoots on a tree. Note that shoot dieback can also be caused by the fungal disease blossom wilt.

Small brown spots appear on the leaves which are often round and fall out later to leave holes – as if the leaf had been hit by shotgun pellets, leading to the popular name of ‘shothole’

• Carry out all pruning in July or August when tissues are most resistant. This is also the best time to prune in order to minimise the risk of infection by spores of the fungus causing silver leaf disease.
• Cut out all cankered areas, pruning back to healthy wood and paint promptly with a wound paint to protect the wound from re-infection