Why Are My Blueberry Branches Dying Back?

Shoot or branch dieback in blueberries — where a stem dies from the tip backward, or a whole cane collapses — is alarming but manageable if caught early and treated correctly. Several distinct problems produce this symptom, and the right response depends on identifying which one is at work. The stem itself, and the point at which the healthy wood meets the dead wood, gives most of the information you need.

Phomopsis twig blight

This is the most common cause of shoot tip dieback in blueberries. The fungus Phomopsis vaccinii enters through wounds, dead buds, winter-damaged tissue or old flower scars and causes the shoot tip to wilt, brown and die back progressively toward the base. The affected tip browns and shrivels rapidly in spring, and the dieback can progress several centimetres down the shoot if not removed. Prune all affected material to clean, white-centred wood, cutting well below the visible discolouration. Sterilise your secateurs between cuts to avoid spreading the fungus. Remove all prunings from the site.

Mummy berry shoot strike

In spring, mummy berry fungus (Monilinia vaccinii-corymbosi) infects new shoot growth and causes it to wilt and brown rapidly — so rapidly that it mimics late frost damage. Multiple shoot tips wilting at bud break, with no clear frost event to explain it, point to mummy berry rather than Phomopsis. The infected shoots are covered in cream-coloured spores that pollinators carry to flowers, completing the disease cycle. Remove all affected shoot tips promptly and clean up any mummified berries from the soil surface to break the cycle.

Frost damage

A late spring frost that strikes after the buds have opened will kill the soft new growth back to the point of frost penetration. Multiple shoots across the whole bush dying at the same level — typically the most exposed growth — strongly suggests frost. Frost-damaged tissue is grey-brown and limp, and the dieback happens suddenly after a cold night. The plant typically recovers by producing secondary growth from lower buds. Pruning back the frost-killed tips to clean wood speeds this recovery.

Canker diseases

Fusicoccum canker and related diseases create sunken, cracked or discoloured areas on larger stems and canes that girdle the wood and cut off water supply above. The symptoms are sudden dieback of a larger branch, with a clearly defined sunken lesion visible at the point of failure. Prune out the affected cane to well below the canker, sterilise tools, and remove all diseased wood from the garden. Cankers are most common on stressed or overcrowded plants, so improving overall plant health reduces susceptibility.