Gummosis: how to recognise and treat it

Growing conditions

Gummosis — Photo: Rosser1954 Roger Griffith, Public domain, Wikimedia Commons

Symptoms

Sticky gum oozes from the trunk or branches and hardens into clear to amber lumps.
Clear gum usually points to a non-living cause such as a wound, frost, sunburn, compacted or waterlogged soil, or planting too deep.
Cloudy or dark gum suggests borers or a disease such as a canker underneath.

Organic treatment

Look for the cause; where the gum is clear and the bark is healthy there is little concern.
Where gum comes from a canker, cut the diseased bark and wood back to healthy tissue.
Have dark, persistent ooze diagnosed by a plant clinic.

Chemical treatment

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Prevention

Plant at the right depth and avoid compacted, waterlogged soil and piling mulch against the trunk.
Keep soil moisture even, neither too wet nor too dry.
Avoid injuring the bark, and prune in the dormant season.
Protect trunks from frost cracks and sunscald.

Plants it affects

Sources

Figures checked against these sources.