Oak Tree Weeping Black Tar: Borer or Wetwood?

The Observation

A mature oak in Melbourne, Australia, developed black tar ooze mid‑trunk over 2 months, worsening.

Possible Causes

• Borer injury: Insect entry allows microbes in; sap ferments.
• Bacterial wetwood (slime flux): Internal fermentation, dark wet stain, odor.

Management

1. Keep tree vigorous—fertilize, water during drought.
2. If borers suspected, apply systemic soil drench (Bayer Advanced Tree & Shrub).
3. Send close‑up photo with scale (ruler/coin) for expert ID.
4. Search “borer damage on trees” images for comparison.