Despite being the largest of all plants, trees are surprisingly easy to overlook. Maybe it’s because their serene, stationary disposition causes them to blend in with their surroundings; maybe we just don’t look up often enough. Either way, like any plant, trees require water, nutrition and ongoing maintenance, so it’s important to take care of the ones on your property. To learn about some tree care basics, we’re joined by six Diamond Certified Expert Contributors in the tree service and landscaping fields.
Tree irrigation and nutrition
The first step in caring for a tree is simple: water it. However, as Chris Chapman of Horticultural Services, LTD explains, tree irrigation is something property owners often get wrong.One common mistake is watering a tree at its trunk. “A tree absorbs water through its roots, so watering its trunk doesn’t make much sense,” he says. “Instead, water should be applied at the outside edge of the tree’s drip line, where the shadow of its canopy is cast upon the ground.” Mr. Chapman says it’s also important to provide an adequate amount of water; ideally, the water should soak down about a foot into the soil. To optimize irrigation, he recommends applying a 4- to 6-inch layer of mulch beneath the tree’s drip line, which will reduce evaporation and improve root absorption by adding beneficial fungi and bacteria to the soil.
Even if it receives enough water, a tree may sometimes struggle to get a sufficient amount of nutrients, especially if it’s situated near a lawn or in an area of dense vegetation. In such cases, a good remedial measure to consider is deep root fertilization. Simon Tunnicliffe of West Valley Arborists, Inc. explains how it works: “Deep root fertilization utilizes hydraulic injection to deliver nutrients directly into the soil at the tree’s root level. The nutrients are conveyed in the form of a liquefied solution, which makes it easier for the roots to absorb them. Besides supplying nutrition, the hydraulic injection’s lateral spray aerates the soil, providing much-needed oxygen to the roots.” Depending on a tree’s individual needs, Mr. Tunnicliffe says deep root fertilization should typically be applied once or twice a year.
Identifying risk factors
Lack of water or nutrition aren’t the only factors that can put a tree in a state of stress—there are also more malicious instigators like bacterial infection and insect infestation. One tree disease commonly found in the Bay Area is fire blight, named for the burnt appearance it gives the leaves and branches of apple and pear trees (in addition to other relatives). According to John Gingrich of Gingrich Horticulture Service, the best way to combat fire blight is to prune it out as soon as you see it, using the correct procedure. “When pruning an affected branch, cut at least 6 to 8 inches below the point of visible infection to make sure no bacteria remain,” he directs. “Since fire blight spreads easily, avoid cross-contamination by sterilizing your clippers between cuts with a high-alcohol disinfectant or a 10 percent bleach solution.”
Justin Greer of Western Tree Removal Specialists points out another often-overlooked source of damage: sunlight. “In particular, young trees and new transplants are at risk of sun damage because their bark hasn’t fully developed,” he explains. “Direct sunlight exposure can create gaping wounds in a young tree’s epidermis, exposing the heartwood and leaving it susceptible to pests and fungal infection, so they should be fortified with trunk protection until they reach maturation.” Mr. Greer says even mature trees can be susceptible to sun damage, especially following major landscape alterations, so be aware of potential risk factors and take measures to address them.
If you have any doubts about the health of a tree on your property, Mr. Greer says it’s best to consult an ISA Certified arborist. “Arborists have extensive, certified knowledge of trees and tree care. To become an arborist, you have to undergo an extremely rigorous process, which includes providing documented hours of field experience and taking a test set to international standards. After earning certification, an arborist must be periodically re-certified, which requires ongoing education and field experience.”
As any property owner knows, a critical aspect of tree care is keeping growth in check with regular maintenance measures like pruning. However, if performed incorrectly, pruning can actually do more harm than good, so before attempting to do it yourself, take a moment to learn the correct techniques. Laural Roaldson of Laural Landscapes, Inc. recommends pruning branches that fall into one of the following categories: dead, dying, diseased, deranged or de-located—aka “the five D’s.” “Dead and dying branches are easy to recognize by their dark, dried-up appearance and texture,” she explains. “A diseased branch can be a little trickier to identify, but in most cases, if a branch exhibits an unhealthy appearance—especially in contrast with the rest of the tree—it’s probably best to get rid of it. A deranged branch is just an unsightly branch that detracts from your tree’s aesthetic beauty, whereas a de-located branch is one that’s rubbing and crossing another branch, which can lead to damage and increased vulnerability to disease.”
Sometimes a tree needs more than mere pruning, in which case it’s good to call in a tree service professional. One beneficial measure is canopy thinning, which Terry Powell of Terry’s Tree Service, Inc. says should be performed periodically throughout a tree’s lifetime. “Canopy thinning consists of removing elements like deadwood, cross branches and excess growth from a tree’s canopy. Besides improving ventilation—allowing wind to pass through the tree more easily—this reduces the canopy’s weight, which subsequently lessens the strain on the tree’s trunk and roots. Furthermore, thinning a tree’s canopy increases sunlight exposure, both to the tree’s interior branches and on your property as a whole.”