John Davidson

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Q & A with a Tree Expert

March 22, 2019
Recently, our Tree For Me Program Coordinator, Amy Howitt, had a chance to sit down with arborist, Tait Sala, from local tree & shrub service experts Cohen & Master to talk about tree planting and tree care in the urban environment. Tait is one of the founders of Cohen & Master and we're very lucky to have had the opportunity to learn from his insight into the world of managing urban trees. We're excited to share some highlights from that conversation with you!

And don't forget, registration to get a free tree for YOUR home starts April 1st for Tree For Me! Visit www.treeforme.ca/plant to see where community events are being hosted and sign up for a tree before April 30th, 2019.


Amy: Tait, can you tell me a bit about Cohen & Master and your approach to working with trees in an urban setting?

Tait: So, as a company, Cohen & Master is a tree service, but we very much believe in trees and people; it’s central to what we do. So, for me, as an arborist, I feel that that's a key piece. Especially in a city -- it's not just about advocating for the trees, but also for what people's needs are, and the interaction of the two. The City is not a “natural” environment; it's not a “natural” forest. We've moved past that point, but we try to emulate the natural forest  as best as we can while dealing with the realities of urban living like changing landscapes from construction, power lines, or neighbour dynamics. We try to find solutions for growing healthy, sustainable trees in the urban environment that reflect the needs of people living among them.

Amy: That seems key. 

Tait: And that’s what most people want at the end of the day. But how we get there sometimes is a challenge. We do often have to work with people to educate them, especially around tree health and viability. Sometimes a tree may appear unhealthy, but in fact, we can make this tree work. We don't need to cut this tree down. Or vice versa. As a company, we try to work with people to make informed decisions around tree care. 

Amy: And what’s your role at Cohen & Master?

Tait: I guess my role is more specifically to oversee all the different departments. Everything from our production division--what we call “General Tree Work” which includes pruning, cabling, and planting--to plant health care, to soil renovations and composting which puts lots of good things back into the soil. We have a consulting side as well where we work with a lot with developers or new builds or renovations, and we also work to consult around City of Toronto bylaws.

The city has has laid out certain regulations, rules and timelines, which can be tricky to navigate, and we have been helping people with that. We see ourselves as an intermediary in those processes. Then there are the administrative aspects of the business like customer relations, which I do a little bit of. An important aspect there is ensuring all of our arborists are consistent in their messaging; that we’re all on the same page and have the same approach to how to handle a tree, especially if new information becomes available. So I float around between those different areas.


Amy: Great! So we get a lot of questions about watering, especially for younger trees since that’s what we offer through Tree For Me. Are there any hard and fast rules about watering young trees? 

Tait: That’s a good question; we get that one a lot, too. I wish there was a cookie cutter answer. The reality is that the trees are in outdoor environments being exposed to whatever the rainfall is that week or that month, which affects their needs. And then where they're situated, what soils are in certain layers, what the drainage is like, is there a downspout close by that's maybe flooding this tree, is it in a sheltered area where it doesn’t get much rain water--these factors all impact how much water a young tree might need. However, I usually recommend watering three times per week, give or take. Preferably a slow soak into the soil, with a trickling hose placed a few inches from the trunk so that the water drains onto the root ball. Move it around a few times and let it saturate the soil for anywhere up to 50 minutes.

But we don't want things too wet, either, so sometimes we recommend testing the soil first by opening it up with your finger and checking for moisture. Sometimes, irrigation systems can cause overwatering, depending on where the tree is planted and what the system is doing. What works well for your lawn may not work so well for your tree... 

Amy: Is there a point at which you can just let a tree be? Maybe after a few years? Or should you always be watching your trees? 

Tait: To some degree, in urban settings, you always need to watch your trees because we do experience weather extremes. Two years ago we had a wicked summer of drought and everything was suffering including mature, established trees.  But then the following summer, while we may get heavy rains, there’s so much stormwater runoff that never makes it into the soils and is instead just flying down the drain. While maybe some of that water is being captured and going into landscapes, still we see a lot of water wastage. So we see plant stress from events like that. I think you always need to monitor. 

I’m definitely of the mind that the first year is critical. The plant can collapse if we don't get those roots moving out into the surrounding soil, starting to establish, getting more of those fibrous roots going.  But if that doesn't happen in the first year, you're in a jam already. You really need to be that caregiver for that first season. We've begun to understand water as a key component of plant health in an urban environment. I'd like to not overlook that. Despite the challenges of pests and disease, one of the primary issues we see is just not getting the water needs met.
 
Amy: We tell people in our Tree For Me training that the first thing to do is to make sure they're putting the right tree in the right place. Do you find there are common “mistakes” people make when selecting a planting location? 

Tait: Yes, I think it's hard for someone to envision how big the tree could get. What type of trees do you give out? 

Amy: We typically offer two large ones: so this year that’s Red Maple and Bur Oak. Then we also offer White birch and Hackberry. And as for shrubs, we have White Cedar, Serviceberry, and this year we're also doing Chokeberry and a Dogwood. 

To be honest, not a lot of people go for the maples and the oaks, probably because they are so big. I think they're pretty intimidating. Serviceberries, people can't get enough of! 

Tait: I can't say I'm most fond of birch; they're a little more sensitive, the lifespan is not as long too; it's not going to be there for 300 years. The Bur Oak can though, and I'm happy Hackberry is on your list. We're seeing how that plant performs and the consensus is  "Oh man, that is a good urban tree," in terms of resilience and tolerance to harsher situations. Plus it has good rooting, fast growth, not a lot of pest and disease issues. I'm really impressed with Hackberry. It’s on my on my top tree list because we have to find urban trees that are going to work with what our environment is becoming. 

And while we talk a lot about the importance of native species--you know, that concept is great--but there are realities of the city that create problems for some native species.  Toronto is not a forest and Red Maples, for example, we see a lot of problems with red maples in Toronto. It's tough. We find issues with elevated P.H. in Toronto and they have a hard time absorbing the nutrients that they need.  My sister-in-law has one and I feel like I've been tending to it for years and it's taking a while to try to turn it around and it's growing so painfully slowly. 

Amy: Oh no. 

Tait: Whereas the Hackberries are like *poof*. One is planted on my street and it's blown past all the other trees. So that's awesome. 

Amy: Wow! We often promote the Hackberry as an easier option, since they're likely to succeed. 

Tait: Encourage the Bur Oak too. I like those. Structurally they're more spaced out so they're tidier looking. But they are slower. People are not going to have a huge tree overnight, but that's another resilient one. 

Amy: Good to know. Are there any trees that you've seen in the city that just don't work here in an urban environment? 

Tait: We've experimented a little bit with Sweet Gum and they struggle because it's not quite the right environment for them and I don't see too many mature ones. We come across them very rarely, but I know City of Toronto is trying to increase their numbers. That's a bit of a question mark. We'll see how they do. They haven't been super strong. Ginkgos -- they're a really cool plant. They're a good urban tree too, but they became really popular and we now have a hard time getting good nursery stock on Ginkgos, so a lot of them are weak. The foliage is small, the root balls just fall apart because they don't have well-established roots. We do like recommending them though because they have a good upright structure, which is appealing in urban environments because people don’t want a giant tree spreading. With a Ginkgo, its growth habit is more upright. Sometimes it develops a co-dominant leader, which needs to be pruned out, but other than that, there’s not much to do. They could put an arborist out of business! But just in terms of the stock, we haven't been super impressed by those. Which is too bad. 

Amy: Speaking of pruning, we get a lot of questions about whether to prune a new tree or whether to leave it be. 

Tait: So pruning at a young age is better as far as structure prunings go. It’s less stressful for the tree. You don't want to put in large pruning cuts on many larger trees because ultimately you're wounding the tree and that's not great. It’s a vector for decay. So we want to keep those cuts small and then if the tree is vigorous and healthy, you can compartmentalize it. It's not going to be an issue. 

Ideally, every tree that I put in, I would like to see it have a central leader with smaller supporting branches. When you think about trees that grow in a forest, frequently that that's how they are. They're going to have a strong central leader and all the attaching branches are going to be smaller than the main trunk. Structurally that's a really important thing; we want it to be about a third of the diameter of the main trunk. Once it starts getting larger than that, it's more prone to failure.

But we don't plant them in a forest. We put them by themselves. So what does the tree do? It expands out and those low branches that would've been shaded out and would have naturally self-pruned and died and fallen off, instead go *vroooom* and become these huge lever arms. We see that a lot. And the other thing is that people like their trees to be a big bushy ball. However, structurally it's a disaster! But, if I pruned it to only four side branches, people would probably think “oh my gosh what did you do to it?” So I think we we have to find that balance with urban trees. So maybe a “perfectly” structured tree it's not going to be reality for urban situations. People might want shade or they might want to block a neighbour’s view.

Many smaller plants are more forgiving as far as the cuts that we're making. We call the proper pruning cuts “cutting at the collar” and these are really important on a smaller plant that's more forgiving. But pruning can be complicated... 

Amy: Yes, while they're small, usually the double leaders have been taken care of by the nursery at that point. And I’ve heard it suggested that once your tree grows and you can't reach, call a professional. 

Tait: Correct. It’s important to be aware of the possibility of over-pruning. One issue is that you can mess up the structure of the plant fairly quickly. And the other issue that I always like to emphasize, is that anything you're cutting out that has foliage on it, that's part of the food source for the plant. You're removing some of that when you prune them out. So we want to make smart choices. We understand that in an urban setting we have to manage the size of the plant and the direction of the plant, but that’s usually years down the road. For the most part, with newly installed plants, my advice is to let it do its thing right now. Let it get established and let its root system take hold. That's what we want to focus on. We want that foliage on there; we shouldn't start picking away at that right away.

Amy: Are there any signs of something going wrong that people should look for on a young tree? 

Tait: Wilting on broad leaf trees - that's going to be the fastest most apparent target. But that doesn't necessarily mean that it's not getting enough water. It might be getting too much water. But that's one of the first things that you might see to indicate that there's plant stress. Browning, too. I generally watch the foliage. If the foliage is really small too--that's an indicator of plant stress. You might see dieback, tip dieback too. That again can be an indicator that the root system is not happy. That's where the issues are going to be in that first year. 

Amy: Do you have any suggestions for residents that are concerned about any possible financial burdens of having a tree in their yard. 

Tait: It's a fair concern. Properties do cost money, especially in an urban context.  And generally, you do have to give trees some attention. It's not like that natural forest environment where we can just put it in and walk away and everything's going to be fine. But in those early years, it doesn't need much, just that basic watering. There are some additional things we can do as arborists in those early years like adding some soil conditioners or other levels of care that are less expensive but that can have a huge benefit in the long run. A small investment in early plant health care could save you from huge costs like tree removal. 

However, trees grow slower than people realize. So some of the major size issues people are concerned about will not be an issue in their lifetime when they’re starting with a smaller tree. The primary investment concerns will be watering, mulch, and placement.  But don't be afraid to reach out to an arborist maybe in year 3 or something like that. Because some of those proactive solutions can actually reduce the long term costs significantly. And we're happy to do it. Come out and get some advice and see what the options are. 

Amy: This is this is a very specific question. If you have a backyard and your neighbour's tree is coming over onto your backyard, whose responsibility is it to prune the tree? Is It a shared responsibility? 

Tait: So that's a great question. Really common. We deal with that all the time. Again, in urban environments, we have neighbors and proximity to one another with property boundary lines everywhere. Plants don't care about that. A couple years back there was a court case where a portion of a tree extended over a property and one homeowner wanted to cut it down the other didn’t and it ended up becoming a court battle. The courts actually ruled that the tree was co-owned. The base of the tree was on property A, but a portion of what was deemed the trunk extended over the invisible property line so it's considered 50/50 co-owned tree. It's not like this person owns 80 percent this one owns 20. That means each party has as equal input on what's going to happen to that tree. 

The City of Toronto has rules around pruning that allow you to prune a neighbour's tree that's coming over your property if it's done to a proper horticultural standard and you're not going to injure the tree. But as arborists, we have a unique set of challenges in these situations. If we get called to prune a mature tree, we sometimes have to enter the tree. But that may require that we cross the property line in order to access the tree properly to do the pruning. Which can create an issue with trespassing. So as a company, we say if you want to do anything to a neighbour's tree, we have to have the neighbour on board. We want to be transparent and explain what will be done and how it might affect their property and seek their permission before commencing work. 

Sometimes neighbours willingly participate in sharing the cost. Generally, the only instances where the owner of the tree is obliged to pay for it is if there's a hazard, which can become a point of tension between neighbours. A City inspector might come out and see the tree and if there's risk associated, they'll issue an order to comply that gives a strict timeline to remove the tree, or have a city crew do it and send the bill to the homeowner. And it can be a big expense...so working together with neighbours to resolve these issues before they escalate is important.  Safety is key, too, and an arborist needs to assess if there is a safety risk. 

Amy: And what about root health? What are some tips when planting young trees?

Tait: With container stock, we have to be careful to try to eliminate those circling roots. It helps to catch them at an early stage because it’s challenging to fix a root problem on an established tree.  Opening up that root ball when the tree is removed from its container by breaking or cutting it and splaying the roots out a little bit is a good strategy, depending how bad it is. We always like to tease out the roots and manipulate the roots so they don't just start going in circles. 

Amy: So you don't have to be too gentle with that? 

Tait: Correct.

Amy: Because we tell people to massage the root ball but it sounds like they really need to be spreading them out as you say. 

Tait: Yeah, you'll see sometimes that the roots come out of the pot as a dense plug or the roots are all on the side. If you put the tree in the ground just like that, the roots will move out, but they're at a disadvantage because they start circling around themselves. So we get pretty aggressive. If it's very fibrous, we'll even take a knife and cut into them to cut them apart. Even a hand cultivator raked through them can help tease out some of the roots. One thing to mention is that you don't want to leave the roots exposed in the sun to dry out while waiting to go in the soil. 

Amy: Okay, and there's not too much damage that can be done when teasing apart the roots? 

Tait: No, they’re a little stronger than people might think because the container stock tends to have tons of fibers. So they can handle a little bit more intervention.  Unfortunately, it’s one of the drawbacks around container stock. But the benefit is that they’re easy to distribute and they’re easy to take home on the subway! You can't do that with burlap or a wire basket. And if someone is planting on terraces, you have to use container stock. 

Amy: Do you think we should be encouraging people with the appropriate space to choose a larger tree species? 

Tait: Yes. One hundred percent. I do think it's an important part of the conversation--to encourage planting large shade trees. They can be managed to work well in the urban environment. Plus we need them for future generations. We're losing trees, even though we're replanting. It’s tough. You know, you can have a backyard the size of this room and still have a shade tree. It’s a viable option.

Amy: So aside from the Bur Oak and Hackberry, is there anything that you think does particularly well? 

Tait: Yeah. In really really challenging locations, maybe a Locust.  It’s decent. People don't always like the small foliage--it can be a bit of a pain next to eaves troughs. London Plane; I've seen success with those. I've seen some failures too... like on Bloor Street. Originally, when they redid the sidewalks, they put in plane trees initially but about 80 percent of them collapsed. They were having a lot of issues with salts getting into those planting pits and they just did not do well. So now they're all Elms -- these Dutch Elm Disease resistant Elms-- that are doing quite well. Valley Forge Elms--that's another that's a good urban tree. It's great that we’re planting elms again because we had stopped because of Dutch Elm Disease. Some of those new hybrid elms are definitely worth checking out as an urban tree. We want to try more of the Pioneer Elm. That's another one we use. It’s a cross that’s  an attempt to emulate the American Elm with its nice sweeping V shape, but I think it's hybridized with Siberian Elm which is not susceptible to Dutch Elm Disease.

Amy: Do those have the Sycamore look to them? 

Tait: Exactly. American Sycamore and London Plane.

Amy: Oh are they the same thing? 

Tait: No, not really. They almost look identical though, and as an urban tree, the London Plane is a little bit better. 

Tree stuff in cities. It's interesting!

Amy: Definitely! Well, thank you so much for chatting with me. We really appreciate it. 

Tait: My pleasure. Really fun to discuss.