Ice causes two types of injury to branches and trunks.
The weight of the ice causes trunks and branches to break. If the limbs do not break, the conductive tissues inside the stem may be injured, resulting in dieback of the plant in the summer. Plants that are regularly bent over by ice can be supported. Smaller plants can be supported with a bicycle tire inner tube looped loosely around the stems but larger plants require cables. Such breakage commonly occurs when wooden props or stepladders are placed under ice-laden branches.