Tony Dickerson answers your questions
QThe bark of my bay tree is peeling and spli ing. Can you tell me why? Roy Anderson, Leicester A Bay trees are popular evergreen shrubs suitable for containers or growing in the ground in a sheltered spot. Neatly clipped, the dark foliage makes great topiary features. In the garden, they can make large, bushy shrubs or small trees to about 7m (23ft).
Splitting and peeling of bark can occur after prolonged cold weather. Many trees suffered extensive damage in the winter of 2010 but we haven’t really experienced that degree of cold in England in recent years. Other possible causes include root failure but unless you’ve lost other woody plants in this area of the garden I think root disease is low on the risk list. Waterlogging, however, could be a possible cause. Bay only thrive on well drained soils in sunny situations, although they will tolerate a little shade.
Another cause could be rabbit, vole or even strimmer damage. Check the lower trunk for evidence. Loss of the bark down to the pale inner wood layer is sufficient to prevent sap flow, causing the bark above to split. Protect young trees and shrubs with guards if necessary in future.
Trees and shrubs can also fail if planted too deeply in the soil, or where the base of the trunk is buried under a mulch. Bark is designed to be above ground and quickly rots if soil or mulch is piled up around the trunk.
The ant activity on the stems in the summer is unlikely to be directly causing harm to the tree. They’re usually collecting honeydew, a sugary substance from aphids or scale insects, neither of which are likely to again be responsible for the bark splitting. The lack of yellowing or browning of the foliage despite the bark damage isn’t usual as tough-leaved evergreens are slow to show leaf symptoms.
Even where all the top growth dies back, pruning to within a few inches of the ground below the bark damage in spring may see rapid regrowth from the roots with shrubs reaching 1.2-1.5m (4-5ft) by the end of the second summer.