What is the sticky sap dripping from my tree?

Honeydew

Honeydew is the sweet, sticky liquid that sap-feeding insects such as aphids excrete. It rains down on whatever is under the tree, cars, patios and leaves, and sooty mold often grows on it. Michigan State University Extension describes it as coming from sap-sucking insects. Look at the undersides of leaves or needles for small soft insects.

Often it is mainly a nuisance, but an arborist can confirm it.

Pitch and resin

Conifers such as pines make resin, which beads at wounds, cones and branch tips. A drip from one spot on the trunk, especially with small holes or reddish pitch tubes, can mean a beetle, which is a different matter; see bark beetles in pines.

Resin that comes out of cut or broken limbs is the tree sealing itself, and it hardens.

Slime flux

The University of Arizona Extension describes slime flux, or wetwood, as a dark, watery exudate that drains from branch crotches, cracks and pruning cuts. It is caused by bacteria infecting the sapwood, often smells bad and may attract insects. The publication says there is no control, that trees with it usually live for many years, and that any weakened limb should be removed if it is a safety risk.

Cottonwood, elm, ash, maple and willow are among the trees it lists as hosts.

What we do

We do not spray or inject, so our role is to identify what you have and decide whether any pruning or removal is called for. Usually a weak limb is the safety issue, not the drip. Take a photo of the drip, the bark above it and the leaves, and send it with the estimate form, or call 775.232.8243.

See arborist consultation for what a visit covers.