When I was a little girl, I balked at drinking my orange juice at breakfast because I didn’t like the pulp. “You’re going to get scurvy!” my mother would threaten.
I never did come down with the classic Vitamin C deficiency ailment that fruit-deprived sailors used to get, however, because my indulgent grandmother gave me grape juice instead. That was one of her many ways of giving me “TLC,” or tender loving care.
Trees may look strong and invincible, but they also need TLC. And although all of the landscape professionals interviewed for this article are ISA (International Society of Arboriculture) certified arborists, they agree that you don’t have to be one of them in order to deliver TLC to your clients’ trees. A minimum, basic knowledge of what trees require is all that’s needed to keep them green and lush.
These experts are also landscape contractors, or work at landscape companies. Like doctors, they’ve seen similar cases over and over again. We can benefit from that knowledge.
Trees need TLC starting from the very first day they’re planted. “The number-one issue we run into is trees being installed too deeply,” said Mark Bartlow, a consulting arborist at Ryan Lawn and Tree, Kansas City, Missouri.
“The root systems begin to fail, and then, so does the tree. Sometimes, if we get there early enough, we can take corrective measures. But there are times when we get there too late, and sadly, the tree has to be replaced.”
This may have happened because the person planting the tree feared a strong wind would topple it. A better practice would have been to stake the tree to keep it upright, until such time as it could stand on its own, kind of like putting training wheels on a tot’s bike.
If you think about a tree’s roots as its lungs, it’s easier to understand why deep planting isn’t good. Roots need air. Sunk too deep into the ground, they can’t access enough oxygen to send up into the tissues of the tree.
Another thing that overly deep planting causes is the phenomenon of stem-girdling roots. “It’s just like what happens in a pot-bound houseplant,” said Andrew Hovland, owner of Branch and Bough Tree Service and Landscape Care in St. Paul, Minnesota.
Unable to penetrate into the more tightly compacted soil around the tree, the roots instead circle around and around the bottom of the rootball. Eventually, they choke off the vascular flow of nutrients and water up into the canopy. “The root girdle acts like a tourniquet,” he said.
If you or I cinched a rope tightly around our necks, the results would be immediate. But trees take longer to choke, and the distress won’t show itself for years.
Hovland’s seen deeply planted trees that have survived ten or 15 years in a landscape. “Then, the owner calls me and says, the leaves are yellowed, or really small, and the canopy is thin. At that point, it’s often too late to correct the problem.”
He’s saved many trees that were in this state by shaving the grade down to root depth. But if a tree’s too far gone, he says your only real choice is to remove it and start over.
What’s the right way to install a tree? The thinking on that has changed over the years.
“The old adage was, use the top of the rootball as a guide, making it level with the ground,” said Bartlow. “Sometimes you’d get lucky and it worked; other times, that root flare, those first-order roots, would be buried inside the rootball.”
The modern thinking is to dig a hole two to five times as wide as the rootball, even wider on sites with compacted soil. The sides should be slanted, and the hole should be no deeper than the rootball is tall, so it can be placed directly on undisturbed soil.
Tree roots typically grow sideways, and stay fairly shallow, so a wide, shallow hole fills the bill nicely. Make sure there is plenty of loose soil; heavy trees planted on packed backfill can sink. An area of loosened backfill has more pore space than the undisturbed soil, so roots can grow into it quickly.
A good rule of thumb is that a tree’s root system should be planted at about the same depth as it grew in the nursery.
A tree given just the right amount of water is a beautiful sight. How much that ‘just right’ amount is varies with the species. “Some trees will tolerate more moist soils,” says Hovland. “River Birch or Swamp White Oak can handle heavier soils and higher moisture content. But a savannah tree like Burr Oak doesn’t want to be sitting in water.”
Too much water can be as bad as too little. Once again, the main issue is oxygen; roots that are drowning are deprived of it. Roots that are constanty under water are also prone to rot. This alone can kill a tree.
If a tree is doing well, it doesn’t need fertilization. In fact, trees are often over-fertilized, according to these experts. It should only be done as needed. If you’re already fertilizing the lawn, some of that will get to the tree’s roots as well.
“Signs of micronutrient deficiency are pretty obvious,” said Steven Geist, senior consulting arborist at Swingle Lawn, Tree and Landscape Care in Aurora, Colorado. “The leaves turn chlorotic (yellow), and they scorch in the summertime.”
He suggests testing the soil first to see what’s really required. “In our soils here, phosphorus and potassium are rarely deficient, so we just give them nitrogen.” Hovland recommends a granular, slow-release fertilizer, such as a 10-10-10, raking it into the mulch ring around the tree.
When we cut our nails, we only trim them to a certain length. Go any further, into the ‘quick,’ and pain and bleeding is the result.
It’s more or less the same for trees. Prune them well, and they flourish; prune them too much, and you can send a tree into shock.
“Branches have collars,” said Anne Taylor, owner and president of Living Elements Landscape, LLC, in Portland, Oregon. “That’s the point at which the branches are attached. I often see them cut into, because someone wanted to make a cut really flush to the tree, and didn’t want to have a little stub left over.”
But if you cut into that collar, you’re cutting into the trunk, and the tree can’t seal that wound off properly. This leaves an open door for insects and diseases to enter. The result is a higher rate of decay, which will weaken a tree as the years pass.
If you aren’t certain about pruning, there’s a plethora of guidance available for you and your employees, from multiple sources. Both the ISA and TCIA (the Tree Care Industry Association) have guidelines on their websites. Both organizations publish inexpensive books in both English and Spanish, with the ANSI (American National Standards Institute) standards for all aspects of tree care that can be used for tailgate training.
County and university extensions can help with information and courses, many of them online. All of these resources can help you and your workers prune with confidence, in a way that helps rather than hurts.
Mulching is great for trees. It helps them hang onto moisture, reduces soil compaction around roots and cools the soil above them. A little of it goes a long way, however.
Our arborists often run across ‘mulch volcanoes,’ organic matter piled a foot high up the trunks of trees. “People are told that two to three inches of mulch will be beneficial,” said Geist. “So they think, ‘well then, ten or 12 inches of it will be even better.’ But it’s not. If you look at a tree in a forest, it won’t have 12 inches of leaf litter or debris around it.”
“Animals can burrow in and make their homes in the volcano, and start chewing on the trunk,” said Geist. “Also, the roots of the tree can start growing into that mulch, then dry out over the winter.” Too much moisture against a trunk causes decay. And piling material onto tree roots suffocates them just as much as burying them too deep does.
How much mulch should be spread around the bases of trees? These experts advise no more than three to four inches, at maximum. That’s plenty.
Topping is the practice of removing the upper portion of a tree in order to shorten it or reduce its canopy. Arborists hate it, because it starts a tree on a downward spiral and hastens its death. After all, it’s tough to thrive when your head’s been cut off.
It’s often done when a homeowner fears that the big, beautiful sycamore in his yard might fall over one day and damage his home. Or when a business owner notices a tree blocking his sign.
“I’ve seen a lot of landscape companies topping trees, and it frustrates me more than anything,” said Taylor. Besides, according to her, it’s counterproductive. If safety is the goal, topping a tree ironically makes it less safe.
“The new growth that comes in consists of what we call ‘suckers,’ branches that aren’t attached very well. There’s a high likelihood that they’ll break off in a storm.” Also, the new growth will come in twice as fast, so if it’s blocking something, it’ll just have to be trimmed again the following year.
Prudent pruning is all that’s needed to make a tree’s canopy smaller and less heavy. If it’s felt that a tree is truly too big, it’s better to replace it rather than top it, says Taylor.
Location, location, location
Ever hear the old expression, “Bloom where you’re planted?” A tree certainly will—if it’s put in the right place.
If not, a tree may survive, but it’ll struggle, and that can shorten its lifespan. Unfortunately, many have been stationed in less-than-ideal spots, either at property owners’ insistence, or out of ignorance by the people planting them.
“Say you’re planting a tree that likes droughty soils,” said Hovland. “You dig a hole, and there’s standing water at the bottom. That’s the normal state of that soil, and you can predict that that tree is not going to do well there.” Ideally, you should try to match the type of soil that the species you’re planting is normally found in.
Another oft-seen mistake is planting trees that normally grow in the understory of forests where they’re shaded all day, in full sun. Like a fair-skinned person at the beach with no sunblock, it’s set up for failure.
If a client insists on planting a tree in a spot you know is wrong for it, apply some TLC by educating him as to why a different choice would work better.
Insects and diseases
When people get sick, they give off signs: sneezing, running fevers and so forth. Trees are no different. This is a good thing; if we pay attention, we can help them before a problem gets too serious. Yellowing or falling leaves at the height of spring or summer, holes and bulges in trunks, dieback of canopies, and dripping sap are are all indications that something’s amiss.
Insects and diseases often work in tandem to hurt trees. “Many of the worst problems are ‘insect-vectored diseases,’” said Rob Gorden, director of urban forestry and business development for Arborjet, Woburn, Massachusetts.
“The mature insect brings a disease into the tree. It’s like bringing your lunch box to work with you, but what’s in it makes everybody sick.”
An example of this is the Polyphagous Shot Hole Borer, an invasive non-native pest recently discovered in Southern California that attacks more than 300 species of trees. It introduces a fungus called Fusarium euwallacea that it cultivates to feed its larvae. This one-two punch of pest-plus-fungus can kill a tree.
Every region has its particular pest and disease problems. The Bronze Birch Borer has hit Oregon pretty hard; Taylor won’t plant any birch because of it. A fungal disease called Oak Wilt has killed thousands of oaks in the Midwest. And the infamous Emerald Ash Borer recently entered Geist’s state, Colorado.
Drought in the New England states has caused the gypsy moth population to explode. Normally, it’s kept in check by a fungus that kills its caterpillars, but lack of rain killed the fungus. “A massive hatchout is expected this spring, which is expected to result in extensive defoliation,” said Gorden.
While not much can be done about huge swaths of infested forest, trees in landscapes are luckier. Fortunately, there are lots of ways to protect your clients’ valuable shade producers using sprays, soil drenches and microinjections.
Some of these treatments will shield a tree for as long as three years. Insecticides delivered via microinjection have the advantage of being confined to only the tree being treated, making them much more eco-friendly.
It’s important to know exactly what species of trees are in your clients’ yards, and about the pests and diseases that plague them, both old and new. There’s lots of information online, such as the several websites devoted to the Emerald Ash Borer alone.
They can keep you up-to-date on the latest areas they’ve invaded, and what treatments are recommended. If you know a pest is getting close to your area, you can treat a vulnerable tree ahead of time and keep it safe.
When to call in an arborist
If a tree seems in dire straits, Geist suggests finding an arborist with a TRAQ (Tree Risk Assessment Qualification). They’re specially trained to identify structural integrity problems.
They know how to spot ‘response wood,’ additional material a tree produces when there is a hollow or weak spot. “If he sees a bulge, that tells him to look for decay. He knows how to tap the trunk with a mallet, or drill into it to assess its soundness. It’s an art.”
Rather than waiting until things reach a critical stage, Bartlow suggests developing a relationship with a good certified arborist, someone you can ask questions of, refer customers to (and vice versa).
You already provide tender loving care to your clients’ grass, shrubs and other plantings. All their trees really need is a little of that same TLC to keep them blooming, shading and thriving for decades to come.