The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
Always prune in dry weather. When carrying out routine pruning, cut branches through the collar (ring of slight swelling found at the base of branches). Healing of wounds occurs most quickly here, compared to leaving stubs (snags) or cutting flush with the bough or trunk. If die-back occurs after pruning, remove dead material to avoid further infection.
Prune out infections promptly and cut back to healthy wood. Do not leave dead wood to moulder and generate spores in damp corners of the garden.
If a plant is attacked repeatedly, check for other stress factors that could be weakening it and alleviate these if possible.
There are no specific fungicidal controls for this disease.
If it is necessary to prune in wet weather when risks of infection are high, or if the plant has previously shown a particular susceptibility to the problem, use a wound paint (Vitax Medo, Solabiol Arbrex Seal and Heal, Growing Success Prune and Seal) to protect the cut.
However, wound paints are not recommended for routine use as they are thought to interfere with healing and may even provide a better environment for rots.