Emerald Ash Borer is the most damaging pest introduced to our forests since Dutch Elm Disease in the 60’s and 70’s. It’s a beetle that hitchhiked here from Asia and has set to devouring ash trees since it was first found in Windsor and Detroit in 2002. It feeds on the inner bark of all species of ash trees and in every case will kill that tree within a few years of first attack. There is no genetic resistance to the beetle and there are no natural predators that can control its spread.
Now that the doom and gloom is over with, let’s get to reality. Urban forests are a vital component of our city. Their canopies that spread throughout our neighbourhoods return tangible and intangible values that cannot be easily replaced or engineered. We need trees, and lots of them in our cities to give us shade and clean air but most importantly, we need them to make our city livable.
The EAB presents a big problem for our urban forest: we have dozens of streets lined with 100% mature ash trees. We have beloved ash trees in back yards and front yards all over the city, tire swings hanging from limbs and all. It is not necessary to submit to defeat and let all of our ash trees die, we can intervene. Affordably and responsibly.
We have some tools to fight against EAB, they’re limited but effective. We can inject our trees with a couple choices of pesticide to protect them from attack and keep them alive as long as we’re able to keep up with treatments every year or two. It’s not cheap, but it’s much cheaper than removal, stump grinding and replacement. Incredibly cheaper if you factor in the dollar value of what a street tree gives us in return.
The decision to intervene couldn’t be simpler on the surface: inject now for a bit of outlay regularly over time or don’t inject and bear the cost of removal and replacement. Where that decision gets more difficult is when it has to be made for a large group of trees, whether it be 10’s of trees or 1000’s of trees. Regardless of the decision, there will be a significant cost, it’s entirely unavoidable.
For a large group of trees (ie. a forest…), it’s most responsible to pick the highest value, strongest, healthiest, largest trees and invest in their protection. The rest are removed and replaced in as long a time period as possible. If this process isn’t planned well in advance, the EAB will spread quickly like wildfire and the cost burden of removal and replacement will be painfully concentrated over just a few years. Not to mention the safety risk of a proliferation of dead trees throughout our city!
Thunder Bay is well positioned to handle this. We’ve known about EAB for years and we’ve been planning for it actively. Now that it’s here we need to act on good planning and be proactive about protecting our best trees so that we can avoid the financial and social pain of losing all our ash trees quickly and suddenly.
Over the past decade and more, our community has been slowly building an understanding and respect for urban trees and all the services they provide to us. We've developed policies, practices and a bylaw that protect urban trees but apparently all this progress was largely ignored at a City Council meeting this past week.
The issue was a complaint from a resident that tamarack needles were falling from the trees in a nearby green space and causing a general nuisance by damaging property. The complainant had asked council directly in a deputation to have the trees removed at the expense of the taxpayer. Although it was a close vote of 7-6, Council chose to remove the trees and replant them with spruce to the tune of about $8,500. This price doesn't include all of the salaries and costs of municipal officials that spent countless hours dealing with the issue over the past several years.
The danger with this decision is that is sets a precedent for residents to have a public tree removed if they choose to complain loudly enough. Where is the line drawn on what is a tolerable nuisance and what is not?. Clearly tolerating tamarack needles falling on a roof is now considered intolerable. What about maple leaves falling on a front yard? What about sap falling on cars parked underneath a boulevard tree? What about spruce needles falling on a driveway? I have a spruce tree in front of my house on the boulevard that shed lots of spruce needles and cones. They scatter everywhere and sometimes one will end up in my shoe or on my kitchen floor. It's the price I pay for having a mature tree to shade my house and to offer the neighbourhood birds somewhere to rest. Where else would I put my Christmas lights?
You can call a tree a nuisance but defining what is and isn't a nuisance is absolutely impossible. Raking leaves may be a bother to one person but to another it's an opportunity to create compost for a garden. Urban forest managers struggle with this constantly; they field complaints from residents who dislike a particular tree yet they are mandated to grow, preserve and protect trees on a large scale.
In my travels, I have never heard of another municipality that has paid to remove a tree because of the foliage it sheds. In fact, Skip Kincaid from the Davey Resource Group said the same thing directly to council the last time this issue came to their attention.
I'm not at all saying that every tree on public property should stay standing until the day that it dies. There are some situations where a tree can be a problem, even a nuisance. Trees that provide a risk to the safety of people or property should be dealt with appropriately but where there is no safety issue, a municipality should not be using taxpayer dollars to remove and replace it.
I was contacted by email by a prospective client who wanted to buy some mulch. This happens all the time but this one was different. What tipped me off was the request to ship mulch to Haiti! I followed this one down the rabbit hole and couldn't shake the scammers. Turns out that scammers themselves are far more gullible than they people they scam. The exchanges below are hilarious. In case you don't know much about mulch, we never irradiate it and there's no such thing as high tech foil wrap.
They finally gave up when I raised their invoice to $400k.
I'm unsure at exactly how they would get money out of me. I have some guesses but I din't follow it through enough to find out.
Don't blame the trees, they're as unhappy about it as you are.
Every season brings different surges of insect populations. This year we are noticing an explosion in scale and aphid populations on our silver maple trees. If you haven't noticed the problem, just look at the line ups to the car washes around town! The tell tale sign of scales and aphids is the honeydew they excrete that drips from the trees on everything below, including shiny cars.
Scale insects are a funny group, they don't really move around much and they are not conspicuous. They feed on the tree by parking along the newer twigs, mostly on the undersides, and piercing their mouthparts into the tissues to extract sap. They filter out what they need and the rest is excreted as what we call "honeydew". This is a clear sticky substance that will adhere to any surface under the tree.
Ants have a unique relationship with honeydew producers; they feed on the sticky liquid. Ants will actually protect the scales and aphids from predatory insects like ladybug larvae. If you find a branch with aphids and ants on it, try poking the aphids with a little twig. The ants will attack the twig to protect the aphids. If you see armies of ants going up and down your tree, there are probably honeydew producers feeding on the tree.
Another sure sign of insects above are blackened surfaces under a tree and blackened branches within it. Sooty mould, a type of fungus, will colonize and spread on the honeydew leaving black splotches on fences, driveways, decks and patio furniture.
Control of these pests is difficult for unlicensed pesticide applicators and impossible on larger trees. On smaller trees you can brush off scale insects or hose off aphids with a hard jet of water. Understandably this gets progressively more difficult as the tree gets bigger.
Licensed arborists can perform trunk injection insecticide application to control the bugs. I caution that tree owners should only employ the use of pesticides if the tree's health is in jeopardy or if the enjoyment of their property is diminished. For example if your silver maple hangs over your deck, if the bugs are bad enough you can't enjoy that space without an umbrella.
Light insect infestations on your trees are nothing to be alarmed about. Most of the time trees can cope just fine with a portion of their energy sapped away by pests.
Fall is here and winter is just around the corner and I'm anticipating what global warming will have in store for us this winter. Perhaps another +20 Celcius March Break or a snowstorm in May? If it's anything like last winter, my staff and I will be busy pruning trees all winter.
Mild weather and no leaves on branches makes for ideal pruning conditions, both for us climbing around the canopy and for the trees.
I've always answered the question of" when is the best time to prune trees?" with "it's not when you prune trees that's so important, it's how you prune them." In most cases quality tree pruning can be performed at any time of the year, spring summer, fall or winter. There are some exceptions for instance we don't prune elm trees during the growing season so as not to attract Dutch Elm Disease spreading bark beetles.
The fall, winter and spring seasons, collectively referred to as "the dormant season" is a fantastic time to get some maintenance pruning and structural training done.
With no leaves on the trees, it's far easier to see the branch structure and to either move around in a tree or maneuver tools inside a canopy from the ground. Since plants, fungi and other critters are generally dormant, there is a decreased chance of infection to new pruning cuts. There's always exceptions to the rule but generally, new tissue will grow over pruning cuts faster if pruning is completed in the dormant season.
When we undertake structural training on medium sized trees, often we need to remove large sections in order to avert future branch failures. This can leave gaps or holes in the canopy that will fill in more readily if pruned in the dormant season.
If you have a schubert cherry tree that is riddled with black knot fungus, pruning must be completed during dormancy to avoid spreading spores and to make sure that all the knots are visible to the pruner.
Some shrub pruning work must be accomplished during plant dormancy. For example, reducing a large forsythia or a cotoneaster hedge back to ground level must be done when the leaves are off. This will ensure that carbohydrates stored in the root systems will be maximized to provide energy to the new shoots that will arise in the spring.
That advice on cutting back large forsythia doesn't scale up to pruning back a Manitoba maple or a poplar. There are no occasions where cutting back a tree, ie. topping, is a good idea for a tree. True, if you are topping a tree, to avoid outright killing it, it must be done in the dormant season. This is why along with the "when" questions should always come the "how" question.
If you are interested in learning more about how to prune trees well, look into the City's Citizen Tree Pruner Program to be offered again this coming spring. Otherwise you could apply for a job with my company and apprentice as an arborist for the required 6000 hours. That's a lot of learning!
I've been betrayed! For many good years of my life I've fostered a loving relationship with a cute little green haired, golden skinned creature. I've helped it grow and spread over many seasons but now I've had enough. It's over.
Amur cherry trees are my former object of desire. They are beautiful trees of smaller stature that display golden peely bark and green leaves that are rarely attacked by fungi and insect. They grow very quickly, are attractive 12 months of the year and they rarely produce pesky fruit to clean up in August.
These cherries have been and still are so widely planted throughout the city because of their attractiveness and vigourous growth. Any given garden centre will have at least a dozen of them in stock but I just can't recommend them any more.
I frequently get called to look at amur cherry trees that have grown well for several years and all of a sudden are showing terrible symptoms of decline. In almost every case, the tree dies. The symptoms range from stunted growth on one or two limbs, a general wilted look or widespread branch death. The exact cause of death isn't as simple as one insect attacking them or a general lack of water and nutrients. Although I haven't pinpointed the exact causes of tree death, I suspect heavily that it's related to our cold climate combined with poor root structure.
Most amur cherries are grown in pots which can encourage roots to circle around the inside of the pot. When the tree is planted in the landscape, those circling roots grow in diameter and choke the main stem. This results in a vigourous tree wilting and dying over the course of a single season. The problem is repairable but only at time of planting and even so the fix is a challenge.
Even if we fixed the girdling root problem, we can't fix the fact that our climate can be unforgiving to tree species whose range does not extend this far north. Even with a warmer climate we will still have fluctuating temperatures that will result in sunscald on bark tissues leading to wounds on the main trunk and larger branches.
Of course there are some exceptions and some of our clients are lucky enough to own a full sized amur cherry with a crown height of 30 feet or more. These trees are fantastic but they're also very rare.
My list of recommended tree species for planting is likely growing as we figure out that more and more tree species can survive up here but it has gone down by one this year. I no longer recommend planting amur cherries unless you are a gambler and want to take your chances that your investment won't die within 15 years of planting.
Before you call the Manitoba Maple (Acer negundo) a "weed", I want you to remember what our winters are like in Northwestern Ontario. It gets really cold and stays really cold for a long time! Typical champion trees that are common in North America like white oak, hickory or sycamore just won't survive the punishment of persistent sub zero tempreatures.
For whatever reason, the Manitoba Maple tree survives our winters exceedingly well and flourishes to become a significant portion of our urban forest canopy. In fact across our region we have countless large, mature and safe maples that return services to us to improve city living conditions by providing shade and cleaning our air. So until climate change alters our winters enough that we can replace Manitoba Maples with White Oaks, stop calling them weeds!
This past year's climate has been so very different from any before. Our winter was much warmer and our spring saw some heat waves that allowed me to go ice fishing wearing shorts and no shirt. We also saw some wild fluctuations in temperatures and an inconsistent amount of precipitation.
Our Manitoba Maples have suffered this year and many of you have likely noticed. Some of the maples are very thin, having lost most of their leaves. Newer growth on some has been stunted to the point where young leaves are barely viable. Added to this, excessive spring rain has increased leaf loss due to fungal diseases.
Not every Manitoba Maple is affected oddly enough. Many are thriving but just as many are showing symptoms that could easily lead to rapid tree death.
On severely affected trees I have not noticed a profusion of a single typical attacker like cankerworms, anthracnose or aphids which leads me to believe that climate is the culprit. When we had warmer temperatures this spring, many trees began to emerge from dormancy and were drawing water from the soil into the branches. Buds started to swell on many species and then we were hit with a week of night time temperature lows of -15 Celcius. This had an effect of freezing water in the twigs and branches which would have surely ruptured many cells. This would have the effect of severely limiting water and nutrient flow from the roots to the leaves.
We saw this effect show up earlier this spring in many coniferous trees from Geraldton to Atikokan.
For Manitoba Maples, the damaged cell problem became apparent only after our season changed from a wet spring to a hot and dry summer. With less moisture in the soil, Maples with a damaged vascular system couldn't pull enough water out of the soil so they started to drop leaves and abort twig growth.
Since we have never experienced a spring quite like this one, I do not know if the affected maples will survive or not. What is best for them right now (and for any other tree species) is to water them at least a few times throughout the summer. Apply water for a few hours near the dripline of the tree so the water soaks into the top one or two feet of soil.
Firstly I need to apologize to the people of our region. The last article that I wrote for this paper was about watering trees and within 24 of press time, we had one of the biggest rainfalls in recent memory. As the consistent victim of Murphy's Law, I take all responsibility for the deluge.
All joking aside, the flooding in the city of Thunder Bay was severe and rare and my thoughts are with all those who experienced losses.
If nothing else, all this rain and flooding provides the best opportunity to illustrate just how crucial trees are in urban environments to assisting in managing storm water runoff. Cities are vast networks of impervious surfaces including roofs, sidewalks, roads and lawns. Although lawns are not truly impervious, as soil get saturated, they offer very little surface area to collect rainwater and heavy deluges often run right off of them.
Large trees of any species offer an immense surface area on which rainwater can be caught and held. When a tree gets wet, the leaves become heavy with water adhering to their surfaces and the bark, from twigs to trunk, also hold surprisingly large quantities of water. As a heavy rain passes, the water stuck to the tree parts begins to evaporate back to the atmosphere and is thus diverted from storm water systems.
In short but intense deluges, trees will act to slow the flow of water from the skies to the sewers reducing the chances of a system overload.
If you don't believe me that trees are essentially giant sponges, just look at the studies that show that a healthy urban forest canopy can save millions of dollars in storm water management system costs. It's easy to visualize if you've ever stood under a big tree during a downpour.
Street trees and landscape trees suck up their share of water but the amount of moisture that forested parks and green spaces absorb is even more immense.
Granted trees won't ever eliminate the need for storm sewers, they should be part of the infrastructure included in any storm water management system. Since trees are simply surface area to temporarily trap water, the bigger the trees are the more water they'll divert from sewers. This is where arborists join the storm water management team.
Trees return the most benefits to us when they are large but it takes progressive thinking to nurture an urban forest to maturity. From just a few years after planting and every 5 to 10 years for the life of a tree, structural training and good maintenance pruning can extend the life of a tree by 50 years or more. Trees are worth an investment in care just as are new facilities, pipes and pumps.
I realize that writing about how to water trees while we've been having many rainy days is not the best timing. You just have to look at North Eastern Ontario to see that weather can change quickly and within a week or so, we may be hit by drought and hot temperatures just as easily as more rain.
Here's a short assignment: before reading any further, take a second to think about where you think the roots of a big tree may be. The answers of "in my sewer pipe" or "pushing up my asphalt driveway" may be true but that's a whole other issue. How deep are tree roots? How far do they spread away from the trunk? How large or dense are they?
First let's dispel some misconceptions. Large trees do not have tap roots and their roots don't go several feet straight down through the soil to find the water table. They also don't magically stop growing at the dripline.
Tree roots are surprisingly shallow. They prefer to grow in the top one foot of soil, their small feeder roots intermingle with grass roots right at the soil surface. They extend very far from the trunk of a tree and although there is no firm rule for their spread, the length of their extension can be double or more the distance of the trunk to the dripline.
The roots right at the trunk, what we call the root flare or the root plate, function only to support the tree (very important!) and to conduct water and nutrients to and from the outer feeder roots. These structural roots don't absorb water and this is important to understand. You never want to douse this part of a tree with water because it won't get moisture into the plant, it will just lead to potential root decay problems.
To provide hydration to a tree, you want to target your watering on the absorptive roots that lie towards the dripline of a tree and beyond. Although some may recommend the "slow drip" method of watering, I'm too impatient for that. Common sprinklers work great as long as you are not applying so much water that it runs off the surface of the soil. A long watering of 1 to 2 hours will ensure that water gets through the grass roots and permeates through the important top one or even two feet of soil.
Make sure the sprinkler that you uses doesn't get the tree leaves wet, this can exacerbate leaf disease problems. Water low, water wide and cover the entire rooting zone of a tree inside and outside of its dripline.
For newly planted trees, you can water close to the base of the tree only for the first year after planting. The second growing season and beyond, watering should be focused well outside the planting hole to encourage roots to spread and grow away from the trunk to avoid root girdling problems.
As always, for the best advice on trees and their needs, consult a certified arborist.
In my last column I had made a prediction that the early warmth of this spring followed by many nights of sub zero temperatures would cause damage to trees. Well, unfortunately, it turns out that I was right.
The vast majority of trees in the region have fared surprisingly well. I was expecting some early leafers like cherries and willows to suffer extensive leaf damage from cold exposure. That didn't materialize but what has become more than obvious is that white spruce trees across the region are experiencing widespread needle loss.
I've been receiving calls from residents in our region as far away as the Geraldton area about this problem. If you look at the majority of spruce trees in just about any location, you will notice the needles are showing a greyish colour and falling off the twigs. The needles on some spruce are turning red before they fall off.
Fortunately many trees within the urban limits of Thunder Bay and along the lake have been spared from this damage because of the temperature buffering effect of Lake Superior.
Conifers are often the hardest hit trees when winter temperatures rise. If daytime temperatures rise consistently while the ground is still frozen and covered in snow, the trees cannot pull moisture from the roots to replenish that lost in the needles. In seasons like this, the advantage a conifer has over leaf trees of using needles for several consecutive years becomes a detriment to their health.
For the most part, the affected trees will rebound and survive just fine. They won't re-grow needles where the old ones were lost but the existing buds should flush out and develop normally. Some trees that are already stressed may not be able to survive with only the new shoots and may not survive the next few years.
If you own some affected spruce trees and would like to help them, you could water their roots and add mulch from the trunk of the tree out to the dripline and beyond. Remember that when you are watering, the absorptive roots are out towards the dripline and not by the trunk. Adding water to the root flare of the tree can lead to decay problems that can destabilize the tree.
If you think your tree may not make it, don't lose hope and fire up the chainsaw yet. They may open more slowly but you should see bud swelling and shoot elongation of new growth over the next two weeks.