Gummosis

Gummosis is a symptom record for gum or resin exuding from bark, not a single pathogen. In citrus, Phytophthora foot rot and trunk lesions are major concerns; in peach and other stone fruit, fungal cankers, bacterial canker, peach tree borers, freeze injury, sunscald, pruning wounds, mechanical damage, and physiological stress can all provoke gum. The gum itself is host material and rarely identifies the cause. Diagnostic value comes from its location, bark condition, cambial discoloration, odor, insect galleries or frass, drainage pattern, weather injury, and host species. This record remains a broad concern/bridge rather than duplicating canonical Phytophthora, canker, or borer articles.

Identification

Operational role: woody-tissue symptom bridge. Record the host, rootstock, age, height of gum above soil, side of trunk, recent cold or heat events, irrigation, soil line, herbicide exposure, and mechanical injury. Remove loose outer bark only as needed to inspect the active lesion margin. Phytophthora-associated citrus lesions commonly begin near the soil line and may show brown cambium under cracked bark; borer injury may include holes, frass, and gum; bacterial or fungal cankers can have sharply delimited sunken margins; freeze injury may follow exposed sides or a documented cold event. Submit active bark that includes healthy-to-discolored cambium, not a vial of dried gum alone. Include roots or crown when the lesion begins at grade.

Symptoms / Signs

Amber, reddish, or clear gum may bead, stream, or dry in crusts on trunks and scaffold limbs. Bark beneath may be healthy, cracked, sunken, wet, foul-smelling, callused, or dead. Associated symptoms can include canopy thinning, leaf yellowing, branch dieback, fruit decline, root loss, or no canopy change at all. Gummosis around individual holes with frass suggests insects; broad lesions at the soil line suggest foot or crown injury; repeated gum at pruning sites suggests wound-related canker. Because causes overlap, gum color and quantity alone are weak diagnostic features.

Life Cycle / Process

No universal lifecycle applies. Pathogen-driven cases follow the biology of the confirmed organism, such as splash- and water-moved Phytophthora, wound-infecting canker fungi, or bacteria favored by cold injury. Insect cases follow the borer’s life cycle. Abiotic cases recur when freeze, heat, sun exposure, poor drainage, deep planting, or mechanical wounds are repeated. Gum can continue after the initiating event and may remain visible after the causal agent is inactive.

Prevention

Plant woody hosts at the correct depth and keep irrigation emitters, mulch, and wet soil away from vulnerable trunk bark. Select adapted cultivars and rootstocks, protect trunks from mower and string-trimmer injury, sanitize pruning tools, and prune during suitable weather. Maintain drainage and avoid chronic saturation. Inspect nursery stock for gum, cankers, and borer signs before planting. Protect young trunks from sunscald or freeze using crop-appropriate methods, not materials that trap moisture against bark.

Management / Control

Do not scrape or paint every gumming site automatically. First identify whether active cambial death, insects, root/crown disease, or a resolved wound is present. Quarantine nursery lots when Phytophthora or a transmissible canker is plausible. Correct irrigation or soil-line contact, remove borer-infested tissue according to crop guidance, and prune cankered limbs only when cuts can be made into healthy wood without destabilizing the plant. Trunk treatments, phosphonates, copper, insecticides, or wound protectants are crop- and cause-specific and must be label supported. Severely girdled trees may not recover even after the cause is controlled.

Procedure Steps

1. Identify host and rootstock and map every gumming site by height and trunk aspect. 2. Photograph gum, bark margins, soil line, canopy, and any holes or frass. 3. Check drainage, planting depth, emitters, mulch, cold events, herbicides, and mechanical injury. 4. With a clean tool, expose a small active margin to assess cambial color; disinfect between trees. 5. Collect bark containing healthy and affected tissue, plus roots or insects when relevant. 6. Submit for diagnosis before applying broad trunk treatments. 7. Route the confirmed case to the applicable Phytophthora, canker, borer, or abiotic record and retain Gummosis only as the presenting syndrome.

Safety Notes

Wear gloves and eye protection when cutting bark; sharp tools can slip on trunks. Do not taste or burn gum or diseased wood. Avoid unregistered trunk injections, caustic wound dressings, and pesticide mixtures. Protect pollinators, workers, and surface water by following crop labels and re-entry restrictions. Dispose of borer-infested or pathogen-confirmed wood as local guidance directs.