Scabby Apples

Among the trees in the garden are an ornamental crab apple (a hybrid cultivar called John Downie) and a regular apple. The latter is a small tree, gnarled and twisted by exposure to the strong, salty winds that regularly blast in off the North Sea, its branches flung southeastwards like arms thrown leewards in despair. For such a small tree, it yearly bears a bountiful harvest of huge apples — all blighted by the rusty brown splotches of Apple Scab (Venturia inaequalis). This is a very common fungal disease of crab apples, and it often spreads to other nearby members of the rose family. (Both apples and crab apples are members of that family.) Unfortunately, we have plenty of rose family species in the garden that might be affected: cotoneasters, hawthorns, and whitebeams among them.

Apple Scab is a worldwide problem now, transported around the globe by trade in apples and ornamental crab apples. It is a serious issue for commercial apple growers, but — other than a bit of unsightliness — isn't really a problem in gardens like ours. The infection rarely kills the tree, though it does pepper the leaves and fruits with blistered brown spots. Treatment typically includes spraying fungicides and clearing the infected fruits and leaves off the ground under the trees, and we'd rather have the many lichens and insects that would be impacted if we were to do so!