Why Is My Tree Dripping Sap? Sticky Ooze Explained

A tree dripping sticky liquid is often not leaking true sap at all — it's usually honeydew, the sugary waste of aphids, scale, or lanternflies feeding in the branches above. Real sap does flow from pruning cuts and storm cracks, and darker, foul-smelling ooze can be bacterial slime flux. Checking the leaves above the drip and the smell of the ooze usually points to the cause.

Most likely causes

  • Honeydew from aphids, scale, or spotted lanternflies feeding above — clear, sticky, everywhere below
  • True sap from pruning cuts or storm cracks — normal, seals over on its own
  • Bacterial wetwood (slime flux) — dark streaks down the bark with a sour smell
  • Gummosis on cherries, plums, and peaches — amber gum blobs from borers or disease
  • Sapsucker wells — orderly rows of small holes weeping sap

Not quite what you're seeing? Answer four quick questions and the clue finder will point you to a closer match.

Compare the possible causes

Possible cause Key signs When it happens How likely
Honeydew from insects above A fine, clear, sticky film coating leaves, cars, patios, or anything under the canopy — often with black sooty mold following Spring through summer, peaking when aphid and scale populations explode Very common
True sap from wounds Clear or slightly cloudy sap flowing from a fresh pruning cut, broken branch, or storm crack in the bark Late winter and spring, when sap pressure is highest, especially on maples, birches, and elms Common
Bacterial wetwood (slime flux) Dark, wet streaks running down the bark from a crack or wound, often with a sour, fermented smell Most visible in warm weather, often on older or stressed shade trees like elm, oak, and poplar Less common
Gummosis on stone fruit Amber, jelly-like blobs of gum oozing from the trunk or branches of cherry, plum, peach, or apricot trees Spring and summer on stressed or infested stone-fruit trees Less common
Sapsucker wells Neat horizontal rows of shallow holes weeping small beads of sap Spring and summer on favored trees Common

Visual clues to check

  • Feel the drip: clear and sticky, coating everything under the tree (and the car), almost always means honeydew, not sap
  • Look directly above the sticky area for clusters of aphids, scale bumps, or lanternflies on twigs and leaf undersides
  • Smell the ooze: a sour, fermented odor with dark streaks down the bark points to slime flux
  • Check for amber, gummy blobs on cherry, plum, or peach trees, which indicates gummosis
  • Trace clear sap to a fresh cut or storm crack — a healing wound is usually harmless
  • Look for a black, sooty coating on leaves and surfaces below, a classic follow-on to honeydew

The causes in detail

Honeydew from insects above

The single most common reason a tree seems to 'drip sap' is honeydew, the sugary excretion of sap-sucking insects like aphids, soft scale, and spotted lanternflies feeding in the branches overhead. It rains down and coats everything below in a sticky glaze, and a black fungus called sooty mold usually grows on the residue — see sticky-residue-on-leaves. Look up: you'll often find the culprits clustered on the undersides of leaves and twigs.

True sap from wounds

Genuine sap bleeding from a wound is usually normal and not harmful. Trees pruned in late winter or spring, or damaged in a storm, may weep for days to weeks before the flow slows and the wound seals over. The tree compartmentalizes the injury on its own; the bleeding looks alarming but rarely needs intervention.

Bacterial wetwood (slime flux)

Slime flux, or wetwood, is a bacterial condition where fermenting sap under pressure seeps out and streaks down the trunk, leaving dark stains and a distinctly sour odor. It looks worse than it usually is and is more a sign of stress than a death sentence, but there's no cure — the best response is to reduce stress and keep the tree vigorous. Avoid the old advice to drill drainage tubes, which only creates fresh wounds.

Gummosis on stone fruit

Gummosis is the thick amber gum that stone-fruit trees produce in response to injury, borers, canker disease, or environmental stress. On its own it's a stress response, but persistent gumming — especially with small holes or dieback nearby — can point to peach tree borers or bacterial canker. Recurring gummosis on a fruit tree is worth a closer look for the underlying cause.

Sapsucker wells

Yellow-bellied sapsuckers drill tidy rows of shallow holes and feed on the sap that flows out, so the trunk can look like it's dripping from evenly spaced points. The straight-line pattern of the holes gives it away — see holes-in-tree-bark for the full picture. It's usually cosmetic on a healthy tree.

When to worry

  • Large, oozing wounds paired with branch dieback or thinning leaves above
  • Dark, sunken cankers on the bark that seem to be spreading or weeping
  • Persistent gummosis on a fruit tree along with small holes, sawdust, or wilting — possible borers
  • Sudden heavy honeydew and sooty mold covering much of the tree, signaling a large insect infestation
  • Slime flux combined with mushrooms or soft, decayed wood, which can indicate internal rot

What to do now

  1. Identify the source first: check the leaves and twigs directly above the drip for aphids, scale, or lanternflies
  2. For honeydew, hose off the sticky residue and rinse cars and furniture; controlling the insects above is the real fix
  3. Keep the tree healthy with deep watering during drought and proper mulching, since most oozing traces back to stress
  4. Leave normal sap flow from a clean pruning wound alone and let it seal naturally
  5. For spreading cankers, borer signs, or recurring gummosis, have a certified arborist diagnose the tree

What not to do

  • Don't carve into, drill, or 'drain' an oozing wound or slime flux streak — it creates fresh injuries without fixing the cause
  • Don't paint or seal the wound with tar or wound dressing; research shows it traps moisture and can slow healing
  • Don't blast the tree with a broad insecticide before confirming the pest, which can also wipe out beneficial predators like ladybugs
  • Don't ignore recurring, spreading, or foul-smelling ooze — persistent cankers can signal disease that needs professional care

Frequently asked questions

Why is sticky stuff dripping from my tree onto my car?

That sticky film is almost always honeydew, the sugary waste of aphids, scale, or lanternflies feeding in the branches above — not tree sap. It coats cars, patios, and leaves, and a black sooty mold often grows on it. Look up into the canopy and you'll usually spot the insects responsible.

Is it normal for a tree to drip sap after pruning?

Yes. Cuts made in late winter or spring, when sap pressure is high, commonly bleed for days or weeks on maples, birches, and elms. The flow slows on its own as the wound seals, and it rarely harms a healthy tree. There's no need to bandage or seal the cut.

What is the dark, smelly ooze on my tree trunk?

Dark streaks running down the bark with a sour, fermented smell are usually slime flux, or bacterial wetwood. It looks worse than it typically is and has no cure, but it signals stress. Keep the tree well cared for, and skip the old advice to drill drainage holes, which only adds wounds.

Related yard clues

Plant Damage Sticky Residue on Leaves: Honeydew and What's Making It A sticky, shiny film on leaves is honeydew — the sugary waste excreted by sap-sucking insects like aphids, soft scale, whiteflies, or mealybugs feeding somewhere above the sticky spot. Look up and check leaf undersides to find the source, and don't be surprised if ants are patrolling the plant: they farm these insects for the honeydew. Read the guide → Plant Damage Holes in Tree Bark: Woodpeckers, Borers, or Bees? Holes in tree bark are most often made by woodpeckers (either neat rows of shallow sap wells or scattered pits where they hunt insects), wood-boring beetles that leave round exit holes with sawdust-like frass, or carpenter bees drilling bare limbs. The pattern, the hole size, and whether you see frass or oozing sap tell you which one — and whether the tree is truly in trouble. Read the guide → Plant Damage White Spots on Tree Bark: Lichen, Bugs, or Mildew? White or grayish patches on tree bark are most often lichen — a harmless organism that simply perches on the bark and is not a disease or parasite. The other common causes are cottony white scale or woolly aphids, powdery mildew on green bark and leaves, or deliberately whitewashed trunks. Whether the growth is crusty, cottony, or powdery tells you which one, and lichen itself never needs treatment. Read the guide → Plant Damage Bark Stripped From Trees: Squirrels, Deer, Voles, or Birds? The height of the damage tells you the most: bark gnawed at ground level is usually voles or rabbits, shredded bark from 1 to 4 feet up is deer rubbing their antlers, and stripped patches on upper branches point to squirrels. Neat horizontal rows of shallow holes are a sapsucker's work — and any damage that circles the whole trunk (girdling) puts the tree at real risk. Read the guide →

Still not sure? Compare with these clues

Mushrooms & Growths Shelf Fungus on a Tree Trunk: A Sign of Decay Inside the Tree A shelf or bracket fungus growing from a living tree's trunk is a red flag: it means the fungus has been decaying wood inside the tree, often for years, before producing that visible 'conk.' The tree may still look healthy, but internal decay weakens its structure — so the right move is an assessment by an ISA-certified arborist, not knocking the fungus off. Read the guide → Bugs & Eggs Tiny White Bugs Under Leaves: What They Are, What to Do Tiny white bugs on the undersides of leaves are most often whiteflies, mealybugs, woolly aphids, or spider mites. The quickest test is to disturb the plant: whiteflies scatter into the air instantly, while mealybugs and woolly aphids stay put in cottony patches. All of them respond to gentle controls — a hard spray of water and insecticidal soap — so there's no need to reach for harsh chemicals. Read the guide →