Diamond Certified Experts: Tree Care Basics

by James Florence

From pruning and irrigation to addressing risk factors, tree care involves several crucial aspects. Photo: World Tree Service, Inc. ©2021

Like all plants, trees have basic nutritional and maintenance needs that must be met in order for them to thrive. However, meeting these needs isn’t as simple as it often seems, which is why property owners need to follow proper protocol when caring for their trees. To learn about this in greater detail, we’re joined by seven Diamond Certified Expert Contributors in the tree service industry.


Tree pruning and maintenance

A fundamental aspect of tree care is regulating growth through pruning and similar routine maintenance. Forest Kirk of Forest Tree Services, Inc. in Santa Rosa explains why this is beneficial. “Maintaining your trees once a year will ensure their long-term health, make your property safer and save you money. With the exception of fruit trees, mulberries and sycamores, a tree’s limbs should be trimmed to leads, meaning one-third the size of the original branch. This will enable the tree to continue growing without losing its structural integrity.”

Mr. Kirk lists some standard measures that are typically included in tree maintenance:

  • Trimming back excess growth
  • Removing dead and crisscrossing branches
  • Performing reductions on elongated, heavy branches to prevent limb failure
  • Identifying poor attachments and wood decay

Another 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.”



Deep root fertilization is a helpful measure for nutrient-deficient trees. Photo: West Valley Arborists, Inc. (2017)

Tree irrigation and nutrition

In addition to pruning your trees, it’s important to water them as needed. However, as Chris Chapman of Horticultural Services, LTD explains, tree irrigation is something property owners often get wrong. One such 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 one to two times annually.



Before attempting to prune a tree, make sure you know what to look for. Photo: American Ratings Corporation. (2017)

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. 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.”

Another tree disease that’s earned an infamous notoriety in the Bay Area is sudden oak death, caused by the fungus-like plant pathogen Phytophthora ramorum. A common sign of this ailment is the presence of a thick, black, sweet-smelling substance staining the lower part of the trunk. While it’s wise to keep an eye out for this symptom on your oak trees, James Cairnes of World Tree Service, Inc. says there’s one thing you should be aware of. “There’s another tree condition that exhibits similar symptoms as sudden oak death: bacterial wetwood (also known as slime flux). It’s basically a fermented, slimy bacterial liquid that oozes from a crack or wound on a tree’s exterior and leaves vertical streaks as it runs down the side of the trunk. Luckily, this occurrence doesn’t have much of an effect on the tree; it doesn’t need to be treated, and it’ll eventually go away on its own.”

Mr. Cairnes explains a couple of ways to tell these similar symptoms apart. “Whereas sudden oak death usually occurs on the lower trunk, slime flux can occur much higher up on the tree. Also, unlike the thick, sweet-smelling character of sudden oak death, slime flux is a thinner liquid and has a rancid odor.” Knowing these symptomatic differences will help you make the right call when inspecting oak trees on your property.

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