Do you have a tree in your yard that looks like it needs some extra TLC? For some good tree care tips, Modern Gardener visited TreeUtah, a non-profit organization whose mission is to improve Utah’s quality of life through tree planting, stewardship, and education. Nicholas Dankers, who is a certified Tree Risk Assessor by the International Society of Arboriculture, is the Planting Coordinator at TreeUtah, and we asked Nicholas about the basics of caring for the trees on your property. He explained that it’s all about balance.
“The above ground part of the tree is reflecting what is happening below ground.” - Nicholas Dankers
When a certified arborist begins an inspection, they might start with an assessment of the tree’s “cone of risk,” which is an area extending out from the trunk, with a distance equal to 1.5x the height of the tree. The location of your tree and the area surrounding it will tell you about potential issues for your tree, and for your property. If your tree has structural instability, property within this cone of risk is in danger and you’ll need to address the issue as soon as possible. Otherwise you could see damage during a storm when weakened trees are likely to lose branches, or have a total root or trunk failure. Think of those home insurance commercials you see with a tree that has crashed into a house! Don’t let that be you!
Consider the direction your tree is growing, relative to objects and structures. Does it need pruning? The tree’s canopy can be pruned into a narrower shape to withstand the forces of a windstorm. For more information about pruning, check out this video and blog post.
The primary consideration for an arborist during a tree inspection starts at the bottom- with the roots. A tree with deep, strong roots is a tree that isn’t likely to fall during a storm. How do you promote strong root growth?
First, consider if the roots are limited by their surrounding environment. If your trees don’t have room to spread horizontally because of structural limitations like a sidewalk, or vertically because of underground utilities or a building foundation, that could compromise the overall health of the tree. If your tree is planted in a confined area, allowing it to self-mulch can help improve a tight situation. Self-mulching means that you leave the leaves that fall in the root zone to create mulch for the tree. Which is good news- less raking is required!
“A common misperception is that trees get their oxygen through their leaves, but the root tissue directly respires with the air, so roots will only grow as deep as they are able to get oxygen.” -Nicholas Dankers
Next, take a good look at the soil surrounding your tree. Is it compacted? If it is, that’s a problem. Compacted soil doesn’t have space for air, which means that the roots of the tree aren’t getting a good deep breath. There’s a simple solution to solve this problem. Using a pitchfork, gently lift the soil at the base of your tree to create more pore space in the soil for oxygen. Turning in mulch and compost will help maintain that porous space over time, and provide nutrients. And most importantly, soil that isn’t compacted will have a greater holding capacity- which brings us to our next very important consideration.
Water. Trees primarily control pests by flushing them out with sap, and if trees don’t have enough water then they aren’t able to produce enough sap to keep pests at bay. Again, it’s all about balance.
To help your tree get the water it needs, place a hose near the roots, and turn on a steady flow of water that will deeply saturate the soil. The water needs to go deep to feed the deepest roots, so follow the guidelines found here for tips about watering your trees. Having decompacted soil helps hydrate roots, which provides hydration needed to flush out pests and keep them at bay.
“Aphids are more of a nuisance than it would ever kill a tree, but it is a sign that a tree is out of balance with its environment.” - Nicholas Dankers
When it comes to pest control, adding extra water is a good first step. If that doesn’t seem to be helping, attracting predatory insects like ladybugs that feed on pests like aphids is the next ideal step. In the absence of these predators, systemic treatments, like a basal drench with an insecticide would treat the tree internally, and is preferable to the long and often-used practice of doing a full tree spray. Spraying an insecticidal soap when the pests are present is another option. But again, most pest problems can be solved by de-stressing the tree by making sure the roots have space to spread, have air and water and nutrients from mulch. If a tree is stressed, it will release different pheromones that can actually attract pests.
Having the healthiest possible tree for its environment will limit the need for pesticides. Giving a stressed tree extra water, as well as aerating and improving the mulch in the tree’s root zone will help restore balance to most native trees in Utah.
We hope this article will help you care for the trees in your yard. TreeUtah offers free tree inspections if you are having persistent issues with your trees. More information is available by calling 801-364-2122 or visiting treeutah.org.
For more resources about caring for your tree, visit the links below!
Utah Community Forest Council: http://www.utahurbanforest.org
International Society of Arboriculture: https://www.isa-arbor.com/
Utah State Extension Urban/Community Forestry: https://forestry.usu.edu/trees-cities-towns/urban-forestry/inde
Utah DNR Forestry, Fire, and State Lands: https://ffsl.utah.gov/index.php/forestry/urban-and-community-forestry