The surest signs of a dying tree in London, Ontario this fall are leaves that turn and drop weeks ahead of the same species nearby, bare limbs at the top of the crown, mushrooms at the base, loose bark and a new lean, and any one of them is reason to book a tree health assessment before the ground freezes. Autumn makes a struggling tree easy to spot, because every tree on the street is changing at once and the one out of step stands out. Here is how CLC Tree Services sorts the normal from the urgent.
Why Is Fall the Best Time to Spot a Dying Tree in London, Ontario?
The Forest City’s mature maples, oaks, ash and beech are the trees most likely to be hiding a problem. The International Society of Arboriculture lists smaller and fewer leaves, dieback in the crown and premature fall colour as classic symptoms of decline, and all three are easiest to judge when the healthy trees nearby set the standard. Fall is also when decay fungi push out mushrooms and conks, and bare branches reveal the dead and hanging limbs an ice storm would take first.
What Are the Signs of a Dying Tree in the Fall?
No single symptom proves a tree is dying, but the more of these you can tick off on one tree, the sooner it should be looked at.
- Early colour and early leaf drop. A maple that turns red in late August while the block is still green, or a tree bare by late September, is in trouble below ground. One side turning early often means a root injury on that side.
- Bare branches at the top of the crown. Trees die from the top down and the outside in. Limbs that carried no leaves this summer are dieback, not dormancy.
- Mushrooms, conks and shelf fungi. Fruiting bodies on the trunk, at the root collar or over the roots mean a fungus is digesting wood inside the tree; honey-coloured clusters at the base each autumn often point to root rot.
- Loose, cracked or missing bark. Peeling sheets, long splits or patches of smooth dead wood mean the living layer beneath has died; on ash, pale woodpecker flecking points to emerald ash borer larvae.
- Sprouts along the trunk. Clumps of thin shoots growing straight out of the trunk, called epicormic sprouts, are a tree’s emergency response to a failing crown; dozens of them are a warning.
- Cracks, cavities and a new lean. A split where two stems meet, a fist-sized cavity or carpenter ants streaming from the trunk all mean decayed wood. A lean that appeared this year, with heaving soil on the opposite side, is an emergency.
- Twigs that snap instead of bend. Scrape a twig with your thumbnail: green and moist underneath means alive, brown and brittle means dead. Check several places; a tree can lose a few branches and be fine.
Which Fall Changes Are Normal?
Not every alarming change in October means trouble. White pines and white cedars shed their oldest inner needles every autumn, so browning inside an evergreen while the tips stay green is normal. Black, tar-like spots on Norway and silver maple leaves are tar spot, a leaf fungus that does no lasting harm. Oaks and beech hold brown leaves well into winter. A young tree that colours early after a dry summer is usually stressed rather than dying; deep watering until freeze-up and a proper mulch ring, as described in CLC’s fall tree care checklist, will often bring it back next spring.
Which Pests and Diseases Are Killing Trees in London Right Now?
Some of the trees that look worst this fall are hosts to pests and diseases new to Southwestern Ontario, and each leaves a recognizable pattern.
Emerald Ash Borer on Ash Trees
Every true ash in Ontario is a host. A thinning crown, dead upper limbs, trunk sprouts, bark splits, woodpecker damage and small D-shaped exit holes add up to an established infestation. Caught early, a healthy ash can still be protected with trunk injections through CLC’s plant health care program; left too long, removal is the only safe option. CLC’s guide to emerald ash borer early detection explains the diagnosis.
Beech Leaf Disease
The newer threat is beech leaf disease, spread by a microscopic nematode in the buds and leaves. The City of London found it here in 2023, and its survey turned up signs in more than half of the individual beech trees checked. Look for dark green bands between the leaf veins, thick or curled leaves and early leaf drop. There is no approved treatment, so the City asks residents to monitor their beech and keep firewood local.
Oak Wilt and Root Rot
Oak wilt is now in Ontario, and a red oak that browned from the leaf tips inward and dropped its leaves in July or August should be checked quickly; CLC’s qualified staff identify oak wilt and assess its severity. Root rot works more slowly, thinning the crown over years, and lab testing confirms the pathogen.
Is the Tree Dying or Just Stressed?
A stressed tree declines evenly, keeps live buds on most twigs and passes the scratch test; given water, mulch, soil care and time, it often recovers. A dying tree has dead wood in the upper crown, fails the scratch test on whole limbs, shows decay on the trunk and gets worse each year. CLC’s earlier guide to the signs a tree needs professional attention covers the structural red flags. CLC Tree Services’ ISA Certified Arborists and Tree Risk Assessment Qualified professionals read the crown and bark, tap the trunk for hollow sections, inspect the roots and go aloft when needed, then recommend whether to treat, prune, support or remove, with an arborist report if you need one for insurance, a sale or a permit.
What Should You Do About a Dying Tree Before Winter in London?
If the tree is stressed but sound, deadwood removal and corrective pruning take out the limbs ice and wet snow would break first, and CLC’s arborists never remove more than 25 percent of the foliage at one time. Plant health care adds deep root fertilization and tree injections where a pest is the cause, and a valued mature tree with a weak union can often be cabled and braced instead of removed, although no support system is a guarantee.
If the tree is dead, badly decayed or leaning toward the house, tree removal before winter is the safer choice, and CLC recommends it when a tree is dead, dying or irreparably hazardous. In London, a privately owned tree with a trunk 50 cm or more in diameter is a Distinctive Tree, and the City of London requires a Private Tree Permit application before it is removed, even when it is a Dead Distinctive Tree in advanced and irreversible decline; CLC prepares the supporting arborist’s opinion. A tree that is an immediate threat to health or safety is exempt from the by-law; that is when the emergency response team comes first.
Frequently Asked Questions About Dying Trees in London, Ontario
How can I tell if a tree is dead or just dormant?
Dormant trees keep tight bark, firm buds and flexible twigs that show green when scratched. Dead trees have brittle twigs, shrivelled or missing buds, loose bark and often fungi on the trunk. A tree that carried no leaves this summer is not dormant.
Can a dying tree be saved?
Often, if the cause is caught early. Trees stressed by drought, compacted soil, construction or a treatable pest frequently recover with watering, mulch, fertilization or injection treatment. A tree with extensive crown dieback, trunk decay or failing roots usually cannot be brought back, and the safer investment is removal and replanting.
Do I need a permit to remove a dead tree in London, Ontario?
If the trunk is 50 cm or more in diameter, yes. The City of London requires a Private Tree Permit application for a Distinctive Tree and a Dead Distinctive Tree alike, supported by an arborist’s opinion. Smaller trees outside the City’s Tree Protection Areas are not covered by the by-law.
Should I remove a dying tree before winter?
Yes, if it is dead, decayed or standing over the house, the driveway or a neighbour’s yard, because freezing rain and wet snow load a dead tree far beyond what it can carry. Winter work is also easier: frozen ground supports equipment and bare branches simplify rigging.
Book a Tree Health Assessment With CLC Tree Services in London
A tree that worries you in October is far easier to deal with now than in a January ice storm. CLC Tree Services has cared for trees in London and across Southwestern Ontario since 1988, with ISA Certified Arborists, Tree Risk Assessment Qualified professionals and licensed Pesticide Applicators on staff, liability insurance and WSIB coverage, and free estimates. Call 519-685-0257, visit 7024 Kerr Road in London, or contact CLC Tree Services online with a photo of the tree, and a certified arborist will tell you whether it can be saved, supported or should come down before the snow.