# Tree decay and damage: fungus, holes, galls, split trunks

> Articles on damaged trees: shelf fungi and hollow trunks, sapsucker holes, wasp galls, included bark, and how to tell what matters from what does not.

11 of 67 articles tagged Decay & damage. By Blue Whale Trees, a native tree nursery in the United States. Web version: https://bluewhaletrees.com/articles/decay-and-damage/. Each article links to its own Markdown page; each tag at the end has a page of its own.

What to worry about and what to leave alone, on trees you already have. When a tree is past saving, the [tree finder](https://bluewhaletrees.com/tools/tree-finder/index.html.md) narrows the natives that would take its place, and the [companion species tool](https://bluewhaletrees.com/tools/companions/index.html.md) shows what belongs beside them.

## Articles tagged Decay & damage

- [Beech leaf disease: the striped leaves, how far it has spread, and whether to plant beech now](https://bluewhaletrees.com/articles/beech-leaf-disease/index.html.md): What the dark stripes on beech leaves mean, how far beech leaf disease has spread and what treatment can do for a yard tree, and whether to plant beech now. Published 2026-10-08; tags: Decay & damage, What to plant.
- [Burls: what makes the big knobs on a trunk, and do they harm the tree?](https://bluewhaletrees.com/articles/burls-on-trees/index.html.md): What makes knotty burls grow on oak and maple trunks, why cutting one off hurts more than leaving it, and how to tell a burl from a gall or canker by the bark. Published 2026-09-28; tags: How trees work, Decay & damage.
- [Twigs all over the lawn: squirrels, twig girdlers, or a tree shedding its own twigs](https://bluewhaletrees.com/articles/why-trees-drop-twigs/index.html.md): Why oaks drop small branches in summer and fall, how the cut end shows whether a squirrel, a beetle or the tree itself did it, and what to do with the twigs. Published 2026-09-28; tags: How trees work, Decay & damage, Oaks.
- [Frost cracks and sunscald: why young bark splits in winter, and what a trunk wrap can and cannot do](https://bluewhaletrees.com/articles/frost-cracks-and-sunscald/index.html.md): Why a young tree's bark splits or dies on its sunny side in winter, which trees are at risk, what a trunk wrap can and cannot prevent, and how cracks close. Published 2026-09-25; tags: Decay & damage, Protection & care.
- [Epicormic buds: the sprouts that appear after damage or new sunlight](https://bluewhaletrees.com/articles/epicormic-buds/index.html.md): Trees carry sleeping buds in their bark for decades. A broken top, hard pruning or sudden sun wakes them. What the sprouts mean and what to do with them. Published 2026-09-15, updated 2026-10-06; tags: How trees work, Decay & damage, Protection & care.
- [Multistem or single stem? Sometimes the trunk is hiding the answer](https://bluewhaletrees.com/articles/multistem-or-single-stem/index.html.md): A trunk that looks like one stem can be two or three that grew together with bark trapped inside. How clumps form, why fused trunks fail, and what to do early. Published 2026-09-15, updated 2026-10-06; tags: How trees work, Decay & damage, Protection & care.
- [Pruning at the branch collar, and when to make the cut](https://bluewhaletrees.com/articles/pruning-at-the-branch-collar/index.html.md): Cut just outside the branch collar, never flush and never leaving a stub. How to find the collar, use three cuts instead of one, and pick the right season. Published 2026-09-15, updated 2026-10-06; tags: Protection & care, How trees work, Decay & damage.
- [Sapsucker holes and the wasps that follow them](https://bluewhaletrees.com/articles/sapsucker-holes-and-wasp-damage/index.html.md): Neat rows of small holes weeping sap are the work of a sapsucker, not a borer. What the bird is doing, who else feeds at the holes, and when it matters. Published 2026-09-15, updated 2026-09-25; tags: Decay & damage, Protection & care, Forests & habitat.
- [Wasp galls on oaks](https://bluewhaletrees.com/articles/wasp-galls-on-oaks/index.html.md): Oak apples, bullet galls, wool sower galls and woody twig knobs are all grown by the tree around a tiny wasp. They look like disease and almost never are. Published 2026-09-15, updated 2026-09-20; tags: Oaks, Decay & damage, How trees work.
- [What old growth actually looks like](https://bluewhaletrees.com/articles/what-old-growth-looks-like/index.html.md): Well under one percent of eastern forest is old growth. The six outward signs of an old tree, where old stands hide, and how to steer a woodlot back toward it. Published 2026-09-15, updated 2026-09-20; tags: Forests & habitat, Growth & age, Decay & damage.
- [Fungus on a tree is not a death sentence](https://bluewhaletrees.com/articles/fungus-is-not-a-death-sentence/index.html.md): Hollow trunks, torn-out limbs and shelf fungi look like the end. Trees can live for decades or centuries in that state, and here is how to tell when it matters. Published 2026-09-14, updated 2026-09-20; tags: Decay & damage, How trees work, Forests & habitat.

## Tags

- [Growth & age](https://bluewhaletrees.com/articles/growth-and-age/index.html.md): 10 articles
- [Measuring trees](https://bluewhaletrees.com/articles/measuring-trees/index.html.md): 3 articles
- [Planting](https://bluewhaletrees.com/articles/planting/index.html.md): 22 articles
- [Protection & care](https://bluewhaletrees.com/articles/protection-and-care/index.html.md): 21 articles
- [Decay & damage](https://bluewhaletrees.com/articles/decay-and-damage/index.html.md): 11 articles
- [How trees work](https://bluewhaletrees.com/articles/how-trees-work/index.html.md): 25 articles
- [Oaks](https://bluewhaletrees.com/articles/oaks/index.html.md): 8 articles
- [Forests & habitat](https://bluewhaletrees.com/articles/forests-and-habitat/index.html.md): 24 articles
- [What to plant](https://bluewhaletrees.com/articles/what-to-plant/index.html.md): 30 articles