Working with an Arborist: Drive-Along Diaries #1

Article by: Jason Deveau (Spray Guy). Click here to see more about Jason and his articles at Sprayers101.com

April 23rd, 3:45 am

I was excited. Today would be my first in a series of drive-along experiences with Ontario sprayer operators. However, to get from my home in Southwestern Ontario to Newmarket, I would have to cross Toronto. This is not my favourite thing to do. But, Dean Solway, Plant Healthcare Supervisor with Shady Lane Expert Tree Care, was based out of Mount Albert and he liked to start at 6:00 am. So, a hot shower and a hot coffee (not necessarily in that order) gave me the emotional support I needed to throw elbows on the parking lot we call the 401.

It was strangely unsettling to see Tim Horton’s closed, and equally odd to see only a handful of cars on the highways. That may have been the fastest, smoothest drive through Toronto that I’ve ever had.


I arrived at the 10-acre lot that has been owned by the company for the last 45 years. I walked past a small, 500 tree nursery they’d recently planted to find Dean in the office. He was busy checking bookings for the day and assigning jobs to his three Plant Health Care trucks (PHC1, 2 and 3). More on those later. After a few introductions, I faded into the background and let them get on with things.

Dean was ensuring the routes made sense and that everyone was ready to go. He explained that the week’s bookings were set each Friday, but that things could always change at the last minute. Front-line administration would handle client calls and communicate with the trucks throughout the day. They also ensured the clients were given at least a day’s notice that someone would be coming to treat Interestingly, the company is also required to inform the client’s neighbours. Dean said it helped avoid potential conflicts such cars, sunbathers or laundry left in the path of potential overspray. Not that such things ever happen, of course.

Operators kept referring to “The Board” which showed their daily assignments. With 2,800 clients scatted over Brechin, Barrie, Oakville, Pickering, Oshawa and downtown Toronto, thoughtful planning and clear communication were critical requirements.

I eavesdropped as Dean talked to a new hire about safety. Filter checks/replacements, face shields, gloves and orange vests were assigned, and I’m confident that it wasn’t staged for my benefit. Operator safety was a theme that came up throughout the day and it was clear Dean took it seriously. As the trucks got ready to roll, he fielded random questions about pesticide rates, tank mixes, crop staging and general agronomy as he double-checked that each truck was properly loaded.

I learned that standard operating practice was to regularly test the equipment and plumbing in each truck. Experience showed it was easier and less contentious to deal with minor leaks and similar issues in the yard than on a Toronto highway or even worse, at a client’s home. That took us outside.


Each truck was equipped with a tablet containing SDSs for all the products they use, PDFs of the pesticide labels and a hyperlink to Health Canada’s Pesticide Label Search website. Many of the products used by arborists are biorational / organic, either by choice or because labels do not permit the use of many conventional pesticides in urban environments. I felt a bit of team-pride when I was told that OMARFA’s Pub 840 is a significant reference document for the company.

As he checked the trucks, Dean noted that it was important to explain to clients that eradicating pests isn’t always possible. Most often it’s about maintenance. For example, today would predominantly be about fungicide applications. Ornamental fruit trees such as crab apple were at risk of scab infection and the window for protection was narrow. Far be it for me to bring up climate change, but Dean did mention that this was the earliest he’d had to apply these products in nine years.

Protectant fungicide treatments need time to dry to be effective. If it were to start raining steadily inside two hours following the application, Dean said the client would be eligible for a re-application ASAP. According to OMAFRA Publication 840, four applications were permitted for this chemistry, and clients were scheduled to receive three at regular intervals over four weeks. That gave time for the applicator to rotate back around, and it left capacity for a possible re-application if required.

Incidentally, I am a master of foreshadowing.


PHC1 and PHC2 were designed to apply plant protection products. PHC3 was strictly for fertilizer and carried an extra 450 L just in case it was needed throughout the day. To remain flexible and efficient, the fertilizer applicators had to be able to take advantage of opportunities if the schedule changed. Returning to reload would be a big loss of productivity, so a little extra onboard was reasonable insurance.

Dean explained that all the trucks were filled either the morning of, or the night before, depending on the product. In the case of compost tea, it’s a three-day process that requires a lot of planning. It must be applied at less than 50 psi to prevent mechanical damage to the living component of the mix. It can be applied to the soil or as a foliar treatment.

We’d be riding in PHC1, which had a single tank subdivided into four separate 170-gallon tanks. The reel was a 60 amp electric auto reel with 300 feet of high-pressure hose. The pump was an AR 813 diaphragm pump, and the motor was a 20 hp twin cycle Vanguard and capable of producing up to 300 psi which is sometimes needed to reach the tops of the highest trees. Dean helped design this system himself and grinned when he said that even as low as 150 psi, you can feel the pistol “kick” in your hand.

Speaking of which, the hose terminated in a quick-connect that allows the operator to swap between a pistol for nearby targets, and a long-barreled rifle for more distant targets. There was also a manually pressurized two gallon bottle sprayer for when the hose-and-gun assembly simply wouldn’t reach.

The last thing Dean checked was that each truck had cleanup equipment, including detergents for any overspray accidents. He explained that most clients want no sign of the trucks coming, going, or having ever been there. That might mean washing away speckles on cars and windows, or marks from the hose being dragged on stonework or past beds and gardens. I’ll share my observations on how urban spraying seems to be viewed by the general public later on.


We’re on the road, passing through Newmarket in the York Region before slipping into stop-and-go traffic on the 404. We aren’t five minutes out before Dean’s phone rings. PHC1 is essentially his office, and he remains in communication via a work phone and headset, relying on a dedicated GPS to guide him from client to client… when the maps are accurate, anyway.

As we drive, Dean notes that rain is forecast so we’ll do as much as we can. He’s set up a linear route going to the furthest client first and working our way back. That way, if it does rain, it will be easier to reschedule because the clients are closer to the yard. He also designs routes that keep the trucks in single neighbourhoods. It’s more efficient and jumping on and off the 407 is an expensive proposition, so they use it judiciously.


According to the docket, we were slated to spray two 12-foot Siberian Crab-apples in the client’s back yard. We pulled up and hopped out. Dean walked us to the back of the house saying, “Let’s go find our patients”. I liked that.


Once located, he assessed the trees’ health to ensure the application was appropriate, and then scanned the area. He explained that an arborist had to be very mindful of the surroundings. He ensured nothing was in the path of the hose or the spray, established wind direction, and then (based on tree height and our distance from the truck) estimated the pressure we’d need for the pistol attachment to reach to the treetops.

We returned to the truck and Dean opened the side to put on his PPE. At the same time, he gave me a short safety lecture. Basically, if I saw anything leaking (on or under the truck) I was to turn off the engine immediately and we wouldn’t go anywhere until we figured out and remedied the issue. Also, should something happen to Dean, I was to call 911. Rest assured, there were no such issues that day.

He ensured the pressure regulator was completely backed off, opened the intake and return valves on the fungicide tank, attached the pistol to the hose and started up the motor. Then he adjusted the regulator to get us to 150 psi. It was obvious he’d performed this dance many times and as he went through the motions, he noted that it was important to get comfortable with the equipment but to always be respectful of it. Then he partially-closed the side panel to reduce the motor noise and started dragging out enough hose to reach his patients.

Standing upwind some distance away, I watched Dean work that first tree. He started with a few, short “test shots” into the ground to get the product to the pistol, and to adjust the width of the spray cone. Then a couple more test shots to the top of the tree to gauge the wind and the pressure. I watched him adjust the nozzle to a tighter stream and start circling the tree, spraying in short bursts until he was satisfied he’d achieved the coverage he was looking for.

Then he detached and drained the pistol before starting back to the truck. I asked what kind of coverage he was looking for and he said the standard was 90% of the canopy covered by at least 90%. That was startling to me given that our unofficial goal for most dilute applications in perennial tender fruit, pome, cane and berry is 100% of the canopy covered, but to a minimum threshold of ~15%. It’s likely due to the different chemistries (I noted earlier that urban applications tend towards biorational products). And, practically speaking, airblast sprayer operators cannot slowly circle a tree, aiming at trouble spots with an endless volume of water. Despite these differences, both methodologies seem to produce acceptable results.


I’ve always been sympathetic of sprayer operators working in three-dimensional crops. Interpreting a North American label’s frustrating lack of guidance when it comes to water volumes for non-arable crops places a lot on the operator’s shoulders. I’ve discussed this disconnect (and proposed solutions) in several other articles. I’ve even co-written a book about it. The problem was particularly acute, here.

Ideally, one would evaluate the target tree’s planted area (which may or may not include an associated portion of alley) and work out the amount of formulated product required for that area. Then, that product must be dissolved or suspended in carrier (typically water) and that gives us the spray mix. Finally, working from the rate the sprayer emits, the operator would determine how much time would be needed to cover the target tree without over- or under-dosing. A good example of the process is found here.

But… how much water is the right amount? How do we reconcile having to achieve such a high degree of coverage? Does that mean using a more dilute spray mix depending on the canopy, or the chemistry, or the method of application? And what happens when the target canopy size can be variable by an order of magnitude, such as going from a small, sparse tree to a huge, full tree? Would the operator have to change concentrations for every job in order to have the right combination of water volume and chemistry to propel and deposit the product uniformly?

There’s no easy answer. Yet I watched Dean deal with this problem at every job, working to keep as much spray on target and use only as much spray mix as required to meet his coverage threshold.


Back at the truck Dean shut off the pump and reeled in the hose through a hand-held rag to ensure the hose came back cleaned of anything it may have been dragged through. Overall, it took six minutes to complete the spray job, but then the clients came out to speak to Dean and that conversation lasted another 10. Client interaction / education is a big part of this job.

By 8:10 Dean had posted a Notice of Service sign in the yard (which must stay there for 48 hours) and punched in the next address on the GPS. As we headed off, he said a big improvement in recent years is the ability to email a Notice of Service and send an invoice right from the client’s driveway, immediately following the service. What traditionally was a 1-2 week wait for payment is now less than a day. If requested, Dean could also write them out manually and leave them at the client’s door.


The next client had five weeping crab apples. These were low trees easily accessed by the roadside truck. Wind was light so low pressure was required. Dean noted that he takes the pressure off the pump between stops to relax the drive belt. He double checked that the pistol was empty and said the reason he drains it after each job was to prevent any possibility of puddles in the truck, on the road or in the client’s driveway. “Customers should never see puddles. It’s better for the environment and it’s professionalism.”

There’s a lot of wash, rinse, repeat from here on, so I’ll only note anything unique to each spray job. In this case, I watched more closely to understand how Dean aimed. A stream of liquid can traverse a great distance without being deflected by wind, but it’s not the cloud of droplets we generally associate with spraying. I realized Dean was shattering that stream of liquid on the larger branches to create the droplets. That’s also why he occasional pulsed the spray by fluttering the trigger; Sometimes the distance warranted a longer throw (long stream shattering of a branch) and sometimes a series of short pulses (shorter throw and the spray broke up on its own). I watched him as he circled each tree, changing his vantage as required. It wasn’t as easy as he made it look, and he was fast.



This was a single, 20-foot high crab apple tree. Dean cranked it up to 225 psi and started with the pistol. Given the height, the wind was more of an issue, so he waited for lulls, using short pulses over short distances and holding the stream for longer distances. He widened the nozzle only when the wind was light and the target was particularly close, but eventually switched to the long gun to reach the treetop.


This time we were spraying a Magnolia tree. Dean inspected the flowers closely. This tree might bloom for 5-8 days and if the flowers are too open, the oil we would use in the treatment might damage them in high UV. Plus, the mechanical damage from the spray might knock them off. But the flowers were still closed enough for the preventative to be applied.

You may have noticed that in this case we weren’t using the fungicide, but instead we’d protect the tree from scale using an oil. So how (I wondered) do we empty the pump and 300 feet of hose of fungicide and exchange it for horticultural oil? Thanks to there being no physical or chemical incompatibility with these two products, it turned not to be the “big deal” it would be for most other spray operations.

Dean opened the draw valve for the oil and kept the return valve open on the fungicide tank. Then he started the pump and hopped up on the truck to spray the fungicide right back into the fungicide tank. When he saw the spray turn opaque, he knew he had primed the oil and stopped spraying. Then he shut off the return on the fungicide tank and opened the return on the horticultural oil tank. The swap took almost no time at all and the subsequent treatment was a breeze.


Stop five was in Snowball Corners in King City and Dean was a little surprised that the work order underestimated the job. We expected a couple crab apples but instead found 20 trees far into a large backyard. Dean took some time with this new client to explain the process, then we fed all 300’ of hose out to reach the trees. We hoped there was enough in the tanks to finish the day!

Winds were high, but there was nothing around and Dean used short bursts and a tight stream shattered on the trees themselves to reduce the number of driftable fines that would be produced by a wide spray. Slowly, picking his moments, he worked up-to-downwind so any overspray hit the next target.



One small Crabapple.


Nine ornamental apples.


I used to think that operations like vineyards and orchards, which often suffer the dreaded urban-rural interface, had the hardest time explaining crop protection to the public. And that’s not just agritourism operations with farmgate sales, either. Throughout the day, however, I elevated arborists to the top of the heap. Case in point:

Before the trucks left that the yard that morning, one of the operators asked Dean about a job in downtown Toronto for a major business on Bloor Avenue. The client did not want applications performed after 8:00 am because hoses on sidewalks are a tripping hazard. They were also restricted from spraying at night because of city noise bylaws (those pumps can be loud).

Accessing the plants can be very difficult and working in downtown Toronto can be exceptionally challenging. Dean knew the spot by rote, saying they should “Come from the street, look to 1 o’clock and 15 m from the statue to find the boxwoods. Then pace the distance to ensure the 300 foot hose would reach. If not, transfer the chemistry to bottle spray. If so, bring the operating pressure up to compensate for the distance.”

Dean explained that the crew-leader of each truck makes the call for the most effective and safest set-up. He went on to relate stories about angry neighbours that responded poorly to seeing staff in PPE, or the grief they would suffer when a flower bed or stone path was marred by the hose. He reiterated throughout the day how much of his job was explaining the spray application process to clients, their neighbours and anyone (read everyone) that might be watching.

Dean said there would always be a way forward if you gave it some thought. “Work the problem. Don’t let the problem work you.”


One backyard crabapple.


Two crab apples in the backyard. This was the last stop and it was perhaps the most complicated. One nearby tree was vibrating with honeybees. The wind was blowing into the neighbour’s yard and the two tall trees were on the property line. Dean really took his time here, rapidly pulsing the pistol whenever the wind died down and directed away from the pollinators. Some overspray moved to the next yard, but it couldn’t be helped. At least it was minimized. All in all we were pleased at the accuracy.

Then the clients, who were new, came home and Dean once again spent time with them explaining the process. We got back in the truck after posting the sign and as Dean emailed the Notice of Service and the invoice, the first few drops of rain started to hit our windshield. All that patience and effort on the last stop and the client would likely need a re-application the next day. Dean was unflappable: “You can’t control the weather.”


We grabbed a late lunch and Dean drove us back to the yard. I’d learned a lot and really enjoyed Dean’s company. He headed back into the office to see how the day went for the other operators and plan for tomorrow. As for me, it had been a long day and I was loathing the punishing drive ahead of me… so I sprang for the 407 toll highway.

Take Homes

Upon reflection, and having written this article over about two weeks, I think I’ll end each article with a few bulleted observations. Bear in mind that I do so based on a sample size of one. That means what I did and what I saw may be unique; It should not be taken to represent an industry, a company, or even the typical practices of a single operator given that we only spent one day together.

  • Generally, label direction does not adequately inform sprayer operators working in three-dimensional crops. I have noted this in fruit protection systems and greenhouse systems, but it may be particularly relevant for arborists.
  • The classic urban-rural interface can cause friction between agricultural production and surrounding residential areas. Not only as a function of pesticide drift, but also noise, dust, odour, etc. Arborists work in urban environments, are scrutinized constantly and are quite often misunderstood by well-meaning people. As such, their job is far more than product application – they spend a considerable amount of time educating and answering questions, making them front-line ambassadors for crop protection processes.
  • The concept of threshold spray coverage (or minimal effective dose) continues to be a difficult and elusive thing. Factors such as mode of action, the nature of the target (surface structure and location), environmental conditions, application equipment and spray quality/concentration are already tricky to say the least. Having watched the relatively dilute, saturating, and highly mechanical applications performed by an arborist I continue to reassess what I think of as “good coverage”.
  • We sprayed 42 trees in roughly seven hours. Productivity, refill time, travel time and the economic considerations common to all spraying have different standards in each agricultural space. Efficiency is, obviously, important to any operation, but this experience reinforced just how different each operation can be. An orchardist may grumble about having to drive between blocks using county roads but imagine doing that on the 404! It’s all relative.

Stay tuned for the next installment.

Article by: Jason Deveau (Spray Guy). Click here to see more about Jason and his articles at Sprayers101.com