Why Is My Cherry Tree Oozing Amber Gum?

Finding sticky amber or orange-brown gum seeping from the bark of your cherry tree is concerning, but it is important to understand that gum production in itself is not a disease — it is a response. Cherry trees, like all stone fruits, produce gum as a defence reaction when bark tissue is damaged, under stress, or under attack. The critical question is what is driving the gum production, because the appropriate response depends entirely on the underlying cause.

What is gummosis?

Gummosis is the term for the production and exudation of gum (a polysaccharide secretion) from the bark of stone fruit trees. It is a physiological response rather than a disease entity — the same way a cut on human skin produces bleeding, a damaged cherry tree produces gum. The gum seals the wound site and inhibits the entry of pathogens. A small amount of gum from a known wound or pruning cut is therefore not a cause for alarm in an otherwise healthy tree.

Bacterial canker — the most serious cause

When gum is produced from bark that has not been physically wounded — particularly when the oozing site has sunken, darkened, cracked bark surrounding it, and the wood beneath is brown and dead — bacterial canker is the likely cause. Bacterial canker kills the cambium layer, and the gum is produced as the tree tries to contain the infection. This form of gummosis is serious, progressive and requires removal of all infected wood as described in the bacterial canker guide.

Mechanical damage

Gum can flow from any wound — pruning cuts, mower impacts, strimmer damage, tight tree ties, climbing children or squirrel gnawing. The gum appears directly at the wound site, and the surrounding bark is otherwise healthy and normal-coloured. These wounds benefit from clean edges (trim any ragged torn bark back to living tissue with a sharp knife) and exposure to dry air. They will callus over naturally in a vigorous tree without further intervention.

Waterlogging and root stress

Trees growing in poorly drained, waterlogged soil produce gum as a whole-tree stress response. If gum appears from multiple sites with no obvious wounds and the soil around the tree is persistently wet, root stress from waterlogging is a possible cause. Improving drainage is the priority. Feeding and mulching will not resolve gum caused by root problems.

Environmental stress — drought and frost

Sudden temperature changes (frost after a warm spell) and severe drought stress can both trigger gum production without any infection being present. This type of gummosis usually resolves when conditions normalise. The ooze sites should be monitored to ensure no disease is developing, but typically no intervention is needed beyond keeping the wound area dry and open to air.