The six signs that most reliably mean a tree needs professional assessment: fungal conks or mushrooms at the base, a new or increasing lean, cracks in the trunk or major limbs, a dead top or large dead branches, lifting soil or exposed roots, and thinning canopy or dieback. Any one of these near a house, driveway or play area justifies an assessment before Fraser Valley storm season, which peaks between October and February.
None of these signs automatically means removal. What they mean is that the tree is telling you something, and an on-the-ground look by someone who assesses trees regularly will tell you whether the answer is monitoring, pruning or removal. Here is what each sign looks like and why it matters.
1. Fungal conks or mushrooms at the base
Fruiting bodies on the lower trunk or root flare are the classic external clue to internal decay. The mushroom you can see is the reproductive structure; the fungus itself may have been consuming structural wood inside the trunk or roots for years. Decay at the base is the worst place to have it, because that is where bending loads concentrate in a windstorm.
What to look for: shelf-like conks on the trunk, mushrooms clustered on the root flare or on major surface roots, and soft, punky or hollow-sounding wood. In the Fraser Valley this shows up frequently on mature Douglas firs, hemlocks and cottonwoods. A proper danger tree assessment will identify whether the fungus is a structural decay species and estimate how much sound shell remains.
2. A new or increasing lean
Established leans that a tree grew into over decades are usually fine; trees engineer their own support as they grow. The dangerous lean is the recent one. If a tree that used to stand straight now leans, or an old lean has visibly increased, the root system may be failing, and root failure is how whole trees end up horizontal.
Check the ground on the side opposite the lean. Cracked, humped or lifting soil behind the trunk means the root plate is rotating, which is an emergency, not a watch-and-wait item. Trees do most of their leaning during and after storms when soil is saturated, so re-check leaning trees after every major blow. If the lean is toward a neighbour’s property, our guide on neighbour tree rules in BC explains the notification steps that protect everyone.
3. Cracks in the trunk or major unions
Vertical cracks in the trunk, splits where two stems meet, and cracked major limbs all signal that the wood is already failing mechanically. Codominant stems, where two trunks of similar size rise from one point with bark pinched between them, are a common weak union in maples, cottonwoods and ornamental cherries, and they split apart in wind and wet snow.
What to look for: a visible seam or crack running up the trunk, especially one that weeps or has callus tissue along its edges, and tight V-shaped unions between big stems. Some cracked unions can be cabled or reduced through proper crown reduction pruning instead of removal, but that call requires eyes on the tree.
4. A dead top or large dead limbs
A dead top on a conifer means something has gone wrong below: root disease, drought stress, bark beetles or physical damage. Beyond the diagnosis, the dead wood itself is the immediate hazard. Dead limbs, called deadwood in the trade, dry out, crack and drop without needing a storm at all, which is why arborists treat large deadwood over targets as a priority.
In the Fraser Valley, drought-stressed cedars and hemlocks have shown top dieback in recent dry summers, a pattern provincial forest health monitoring has tracked across coastal BC (see gov.bc.ca forest health resources). A tree with a freshly dead top over a lawn may only need the dead section removed; the same tree over a bedroom deserves a full assessment.
5. Lifting soil, heaving roots or a cracked root plate
The root plate is the tree’s foundation, and soil movement around the base is the foundation telling you it is losing grip. This sign matters most in exactly the conditions the Fraser Valley gets every fall: weeks of rain that saturate soils, followed by outflow or frontal winds. Saturated soil holds roots the way wet sand holds a fence post.
What to look for: soil cracking or mounding on one side of the trunk, roots that have visibly lifted lawn or pavers, severed roots from recent excavation (driveways, drainage work, pool installs), and a spongy feel underfoot near the base when the tree moves in wind. Construction root damage deserves special mention: a tree can take several years to fail after roots are cut, so “it has been fine since the reno” is not evidence of safety.
6. Thinning canopy, early colour change or dieback
A canopy that thins year over year, turns colour weeks before its neighbours, or dies back from the outer branch tips inward indicates declining health, and declining trees shed limbs and invite decay fungi. One stressed summer is not a verdict; a multi-year trend is a real signal.
Compare the tree to others of the same species nearby. If your birch is half bare in July while the one across the street is full, or your cedar hedge is browning in patches that expand every year, get it looked at. Sometimes the fix is cultural (water, mulch, removing girdling roots) rather than a chainsaw, which is exactly why assessment comes before removal. Seasonal timing for corrective pruning is covered in our guide to the best time of year to trim trees in the Fraser Valley.
What should you do before storm season?
Work through this checklist in late summer or early fall, before the first atmospheric river:
- Walk your property and look at every tree within falling distance of the house, garage, driveway and play areas.
- Check each tree against the six signs above, from the root flare up.
- Photograph anything concerning, with a wide shot and close-ups, so changes can be tracked.
- Book an assessment for any tree showing a sign near a target. Get findings in writing if you may need them for a permit application or insurance.
- Do the corrective work in fall, not in January. Crews and schedules are far better before storm season than during it, and planned work costs less than emergency storm response.
WorkSafeBC treats danger tree work as a specialized, high-risk activity with its own procedures (see worksafebc.com), which is a good indication of how seriously a suspect tree should be taken by a homeowner with a ladder.
The bottom line
Conks, new leans, cracks, dead tops, lifting roots and dieback are the six signs worth acting on, and any of them near a target is worth a professional look before October. Most assessed trees do not need removal; the point is knowing which ones do while it is still a planned job. If something on your property matches this list, book a danger tree assessment or request a free estimate and we will tell you honestly which category your tree is in.
Frequently Asked Questions
When is storm season in the Fraser Valley?
The worst tree-failure weather runs roughly from October through February, when Pacific frontal systems bring repeated windstorms and atmospheric rivers saturate the ground. Wet soil plus wind is the classic windthrow combination for shallow-rooted conifers. The best time to assess and fix problem trees is late summer and early fall, before the first big system arrives.
Are dead trees always more dangerous than live ones?
Dead trees are always a hazard near targets because wood dries, cracks and sheds, and dead conifers lose strength over time. But live trees cause plenty of storm damage too, especially fully foliated trees with root or trunk defects, since the canopy acts as a sail. A live tree with a fungal conk at the base can be more dangerous than a bare dead stem in an open field. Location and defects matter more than alive versus dead.
Do mushrooms at the base of a tree always mean it must come down?
No, but they always mean it should be assessed. Some fungi are harmless to structure, while conks of decay fungi on the lower trunk or root flare often indicate internal rot where the tree needs strength most. Only an on-site assessment, sometimes with sounding or probing, can tell how much sound wood remains.
How much does a danger tree assessment cost?
A single-tree residential assessment in the Fraser Valley is typically a modest flat fee, often around the low hundreds of dollars, with written reports for permits or insurance costing more depending on detail. Compared to an uncontrolled failure onto a roof, or an unnecessary removal of a healthy tree, it is the cheapest step in the whole process.
Can a tree that survived past storms still fail in the next one?
Yes. Each storm event loads a tree differently depending on wind direction, soil saturation and what has changed since, such as new root damage, progressing decay or the loss of neighbouring trees that used to shelter it. Trees exposed by nearby clearing are a classic Fraser Valley failure pattern, because stems that grew inside a stand suddenly take full wind alone.
Published July 25, 2026 · Last updated July 25, 2026 · Fraser Valley Tree Service