A dead ash tree in the GTA: the permit, the hazard and where the wood may go

If there is a bare, grey-limbed tree standing in your yard this September and it is an ash, three separate decisions are waiting, and the order matters. One is the municipal permission, which in Mississauga carries a review period of 30 business days. One is the removal itself, which gets harder and more expensive the longer a dead ash stands. The third is the wood, which is federally regulated and cannot simply be driven wherever is convenient. Starting with the permission costs nothing and runs in the background while everything else happens.

How do you know it is an ash, and that the borer is what killed it?

Emerald ash borer feeds on every ash species growing in Ontario — green, red, white, black and blue ash, plus non-native European ash — so identification only has to get you as far as the genus. White ash is the largest of Ontario's native ash species and a common one in this area; the province describes it as having opposite compound leaves with five to nine leaflets, typically seven, and mature bark with a distinctive diamond pattern. Opposite arrangement is the quickest check from the driveway: leaf stalks and twigs emerge directly across from each other rather than staggered along the stem.

The borer leaves marks that are specific enough to settle the question. Ontario's Ministry of Natural Resources describes the adult exit holes as D-shaped and four to five millimetres across, and the larval feeding tunnels under the bark as shallow, meandering S-shaped galleries with abrupt turns. Two more signs are easier to spot from the ground:

• Thinning from the top down. Reduced leaf coverage with bare outer branches, while the lower trunk still looks alive.
• Epicormic shoots. Leafy sprouts pushing straight out of the trunk and main limbs from buds that had been dormant for years — the tree responding to the loss of its canopy.
• Woodpecker work. Larger, ragged holes and pale flecked patches where birds have stripped bark to reach larvae underneath.
• D-shaped exit holes. Small and flat-topped, four to five millimetres across, scattered on the bark of the trunk and larger branches.
• Vertical cracks in the trunk. Listed by the province alongside the exit holes and crown death as a sign of borer damage on white ash.

Adults emerge in June and July, but exit holes stay on the bark long after the beetle has gone, so finding them tells you the tree has been attacked without telling you when. That is one reason the assessment belongs to someone who can read the whole tree. The City of Mississauga's guidance is to have an ash inspected by a certified arborist, who can say whether it is infested and whether treatment is still an option; Toronto asks for an arborist certified with the International Society of Arboriculture or registered with the American Society of Consulting Arborists. Injection with a registered insecticide protects a tree from attack rather than undoing damage already done, which is why it is a decision for a tree that still holds most of its canopy.

Why a dead ash gets dangerous faster than other dead trees

This is the part that changes the timeline, and the Town of Oakville states it plainly about its own woodlands. Of roughly 43,000 ash trees in Oakville's woodlands, most or all are now dead or dying, and in the Town's words they are "becoming brittle and structurally unsound due to the lack of nutrients caused by the EAB larva tunneling under the bark. Brittle trees can lose limbs or fall." The borer girdles the tree by destroying the thin layer of conducting tissue just under the bark, the wood dries out, and the structural strength goes with it.

The second consequence is that this is not a tree to take down yourself. A standing dead ash anywhere near a house, a fence, a driveway or a hydro line belongs to an insured arborist with the right equipment, and no amount of preparation on your part changes that. We have written separately about when renting the equipment beats hiring the job out; a dead ash sits firmly on the hiring side of that line.

The permit question has a different answer in each municipality

Being dead does not remove a tree from these by-laws. In Oakville, Burlington and Mississauga a dead ash over the size threshold still needs a permit — the fee is what gets waived, not the permission. Toronto is the one place in this area that drops the permit for a tree that is 100 per cent dead, and it replaces it with a written confirmation you have to obtain first. The general thresholds and the boundary-tree rules are covered in our post on who owns the tree and when a permit applies; what follows is what each municipality does once the tree is dead, dying or an ash.

Two details in that table matter more than the thresholds. The first is Toronto's permit exception: a tree that is 100 per cent dead needs no permit, but the City's wording is that you must request and receive a permit exception confirmation before proceeding, unless immediate work is required to eliminate a dangerous situation. An arborist report is recommended but not required for that request — staff can inspect the site instead. The second is the gap between dying and dead. Toronto states that a permit is still required for trees in poor condition, so an ash still holding leaves goes through the full application while the same tree, once bare and dead, goes through the exception request.

Mississauga publishes a review time of 30 business days from the date a complete application is received. Counting from late September, that lands after the first hard frosts. It is the single strongest argument for starting the paperwork before you start collecting quotes.

Each municipality also has an emergency route. Oakville requires no permit where there is an immediate risk of serious injury or damage, but asks to be notified as soon as possible; Burlington exempts emergency tree work provided supporting documents are sent to the City afterwards; Toronto's exception process carries the same carve-out. These provisions exist for a limb on the roof at 2 a.m. Reaching one of them means the removal happens on the worst available terms.

Where the wood may legally go

Ash wood is a federally regulated article, which is the detail that turns a straightforward cleanup into a problem once the tree is already on the ground. The Canadian Food Inspection Agency prohibits moving ash trees, logs, branches, lumber, bark, wood chips and ash firewood out of a regulated area without written authorization, and the prohibition covers yard waste as well, because yard waste may contain ash bark and trimmings. Moving ash firewood out of a regulated area is explicitly banned for private purposes, including taking it to a cottage or a campsite.

The Ontario regulated area is large — the CFIA's description takes in Toronto, Halton, Peel, York, Durham, Hamilton, Niagara, Waterloo, Simcoe, Muskoka, Haliburton, Parry Sound and Ottawa among others — so the practical step is to find your intended destination in that description before the wood goes anywhere. Peel Region goes further for its own residents, stating on its yard waste guidance that moving ash trees and ash wood out of the borders of Peel is prohibited. Keeping the wood inside your own region satisfies both instructions.

Oakville has one extra option: Halton Region lists a Bulk Brush Call-In Collection in Oakville, arranged through 311. It does not change the stump rule, but it can clear a pile that would otherwise take several trips.

What to do over the next two weeks

1. 1Confirm it is an ash and photograph itOpposite branching, compound leaves, diamond-lattice bark. Take clear photos of the whole tree and close-ups of any exit holes or bark flecking. Every permit and exception process in this area asks for size, species, condition, location and photos, so the same set of pictures serves all of them.
2. 2Measure the diameter at 1.37 m above the groundMeasure the circumference at that height with a tape and divide by 3.14. That single number decides whether your municipality's threshold applies at all — 15 cm in Oakville and Mississauga, 20 cm in Burlington's urban area, 30 cm in Toronto.
3. 3Start the municipal step before you collect quotesApply in Oakville, Burlington or Mississauga; request a permit exception confirmation in Toronto; check the Halton Region by-law if you are in Milton on a large or Greenlands property. The fee is waived or nil for a dead ash in each of the three towns that require a permit, so the only thing you spend is the wait.
4. 4Get quotes from arborists, and ask each one about access and the woodA brittle ash may need a bucket truck or crane. Ask how the tree will be taken down, what happens to the trunk, and whether the stump is included or separate. Those three answers explain most of the difference between quotes.
5. 5Plan the replacement while the paperwork movesOakville and Mississauga both require replacement planting as a permit condition for healthy trees, and Burlington offers a free tree through its giveaway programme where a dead or terminally declining tree is removed. Autumn is a workable planting window in the GTA — the what to get right when planting in the fall side of this is mostly about watering until the ground freezes.

What the municipality will and will not do for you

If the ash is on the boulevard or in a park, it is the municipality's tree and its removal is the municipality's job — report it and they will assess it. Oakville is injecting roughly 750 Town-owned ash trees this year and replacing removed street and park ash with other species. Mississauga's position on private trees is equally clear: its active management plan does not include resources to treat or remove private ash trees, and the tree on your lot is yours to deal with.

There is one case where doing nothing is defensible. An ash standing in the back of a deep lot, well away from the house, the fence line, the driveway and anywhere people walk, is not an urgent removal. Standing dead wood has real habitat value, and leaving it is a legitimate choice as long as nothing it can reach matters. Pace out the height and check what sits inside that radius in every direction, including next door, and repeat the check each autumn as the tree keeps deteriorating. The case for waiting stops the moment the fall line crosses something that matters.

Where a landscaping crew fits

Felling a dead ash is arborist work and we do not pretend otherwise. What the arborist leaves is a different job: ruts across the lawn where equipment stood, a spread of chips, a stump, and a bed that has just gone from full shade to full sun. That is ordinary property work, and it slots into an autumn schedule more easily than into a November scramble — the same argument as deciding what gets done to decks and fences before winter.

Debris set-out is where the two jobs meet. Brush inside the bundle limits above goes out on a normal yard waste day; everything else needs a vehicle and a waste site. Our seasonal cleanup work covers clearing and bagging or piling debris to local set-out rules, with stump removal and replacement planting listed on the same page.