Malus species, such as apple and crab apple, rowan and mountain ash species can be attacked and less frequently, beech and some other trees.

Apple canker is a fungal disease causing disfiguring and sunken patches of dead bark on the branches of apple and some other trees. Infections often begin at wounds or buds.

Main Symptoms:

Round or oval areas of dead, sunken bark cankers are perennial, with the affected area covered with dead bark that shows concentric rings indicating periods of active spread. Older cankers lose the bark, exposing dead wood in the centre. Perennial cankers develop raised edges as the tree’s bark attempts to grow back over the exposed area. Eventually the branch will die above the canker, being progressively weakened as the bark is killed.

Caused by a Fungus; new cankers form from mid-spring.