Gummosis
A symptom in citrus, mango and stone fruit trees where sticky gum oozes from the bark, usually in response to disease, pests, wounds or stress.
Also known as: Gum disease, Gumming
Symptoms and identification
Amber to dark brown gum oozes from cracks or wounds on the trunk and branches. The bark underneath may be dead and sunken. In citrus, bark can crack and peel, leaves yellow and thin, and branches die back.
Causes
Gummosis has several causes: Phytophthora fungus in damp bark, borer insects, canker, wounds from tools or mowers, waterlogging, nutrient problems and cold damage. Trees planted too deep or with soil piled against the trunk are at higher risk.
Organic treatment
Scrape off the diseased bark back to healthy tissue in dry weather and leave the wound open to heal. Control borers and correct watering, and apply a lime wash to the lower trunk to protect it.
Prevention
Plant with the graft union well above soil level, keep soil and mulch away from the trunk, avoid trunk wounds and improve drainage. Water the soil, not the trunk.
Chemical treatment (use with care)
A copper-based paste or fungicide labelled for the cause, such as Phytophthora, may be applied to the cleaned wound as the label directs.