As the summer storm season hits the mid-Atlantic, arboreal and safety concerns heighten for many Georgetowners who have trees to protect. What are some tree-care tips an expert might recommend?
The Georgetowner interviewed Lou Meyer, a certified arborist with close to 20 years of tree-care experience. Meyer is employed with the Davey Tree Expert Company, an international firm which has served the D.C. Metro region for close to 100 years.
For residents with cherished and valuable trees, Meyer recommends having trees inspected by an International Society of Arboriculture (ISA) certified arborist “at least every other year, if not every year.” Be wary, however, of fly-by-night operators who charge for estimates. “Respectable arborists come out and do evaluations at no cost,” Meyer said.
As the storm season approaches, Meyer emphasizes the need to have your larger trees inspected for possible dangers. “The hazards come in when we talk about the summer storms starting to heat up right now,” Meyer said. So, the first step in a tree inspection is to check for “any dead limbs up in the canopy.” That would be the “first and most glaring sign the tree’s in trouble.” Not only might the tree be decaying internally, but dead limbs might come crashing down.
Avoiding the Wind Sail Effect:
Meyer suggests having a tree-care specialist prune out dead limbs in the tree canopy. In addition, he suggests a “routine maintenance prune” to thin out the crown of the tree, “remove any branches that are crossing or rubbing against each other, and to look for clearance off buildings” that could damage shingles or siding or make it easy for “squirrels and racoons to get into your house.”
Thinning out the canopy carefully also helps reduce the “wind sail effect” where trees with thick canopies are more easily blown over in high winds. Allowing more airflow through the canopy helps prevent moisture and rotting in the upper branches as well.
In a tree inspection, Meyer would next move down to the tree’s trunk looking for two possible areas of concern. First, does the tree have any large or gaping wounds from natural or human causes? Such wounds to the tree’s outer bark or internal fibrous support structure might damage nutrient circulation or make the tree more prone to toppling. Second, are there any signs of harmful fungal growth, especially near the root mass (the tree’s “pressure point” in high winds)? While lichen is fine on trees, other “fruiting bodies” such as “conks” or “shelf mushrooms” or other saprophytes that feed on a tree’s decay must be addressed by boosting the tree’s immunities and/or applying pest controls.
Be Careful with Pest Control
Once trees are weakened or injured they become more prone to pests. “If a tree is in decline,” Meyer said, “it’s much less likely to be able to counter those pests… So, if you see pests heavy in a tree, that’s a sign that maybe there’s something going on that may not be visible to the eye.” On Oak trees, Meyer looks for signs of “scale” or “sooty mold.” The sugars released from insect excretions — known pleasantly as “honeydew” — are a plentiful source of food for such molds, so they’re a good clue that invasive pests have penetrated the tree.
While pest control sprays might be called for, Meyer strongly recommends consulting a tree expert about application. “I think a lot of people overreact. There are a lot of chemicals released that don’t necessarily need to be released.” Many certified arborists, including Meyer, use the integrated pest management (IPM) system to determine the pest control applications and avoid using excess chemicals that can harm biotic systems and damage estuaries and riverways.
After examining the trunk of the tree, a proper tree inspection would then carefully consider its “root crown” (i.e., base root structure.) Where the tree meets the ground, Meyer would look for a “nice root flare” with the trunk widening out and spreading roots just beneath the soil. “You don’t want your tree looking like a telephone pole that’s going straight into the ground with no flare at the bottom,” Meyer said. A strong “root crown” with healthy “root flare” helps prevent two problems: moisture rot at the tree’s base and the spread of “girdling” or “adventicious roots” that choke off or strangle the tree’s nutrient circulation at the Vascular Cambium at the tree’s base.
Why You Shouldn’t “Volcano Mulch”
When tree owners engage in “volcano mulching” — or piling up a mound of mulch against the base of the tree — rot can take hold and the tree’s food intake can be cut off. “One of the biggest concerns with ‘volcano mulching’ is that the tree will send out those adventitious roots and…. they’ll just start wrapping around the trunk of the tree. It’s like a tourniquet around your wrist. But you want those nutrients and that oxygen and that water to flow through the Vascular Cambium,” Meyer said.
Meyer recommends owners apply mulch “one to two inches deep at the most, and four to six inches away from the trunk of the tree, so you don’t pile it up against the trunk.” Mulch is “fantastic for trees,” he said, “too much mulch in the wrong place, however, is an issue.” Homeowners should also remember that turf competes aggressively with tree roots for nutrients, so a wider mulched area around the tree’s base is recommended. He also recommends Biochar — a charcoal mix — to help chemically bind nutrients to the soil. “It’s something I’m really jazzed about,” Meyer said.
Why Are Oak Trees Dying?
Meyer is concerned about the severe die-back of large oak trees in the region. He’s seen the problem “across the mid-Atlantic.” At every arborist convention, he said “the number one question is what is going on with these oak trees? And, it’s not looking great.”
Root system damage to the oaks is one obvious cause. New sidewalks, driveways, home construction and other invasive projects often tear up critical parts of the tree’s expansive root crown, eventually starving the tree of nutrients and weakening its support structure. To strengthen root systems, Meyer also suggests asking a professional arborist about applying a “growth regulator” to coax the tree into producing less crown and more root mass.
Is Climate Change Having an Impact?
Weather patterns are another huge concern and Meyer has no doubt that climate change has been a big factor in regional tree damage. “A lot of these oak failures we’re seeing in the mid-Atlantic region come from the heavy rains in 2018. We had record rains in 2018 and oak trees especially — unless you’re a swamp white oak — do not like standing water.” The following year, Meyer recounted, “we had six months of drought. So, these trees are now starving for water…. And you can have all the nitrogen, phosphorus and potassium in the soil you want, but without water to break that down to absorb those nutrients, the trees are not going to get any.”
Extreme temperature fluctuations associated with climate change have stressed and exhausted many trees. “We’re seeing these wild weather patterns where, if you go back to 2020 last February… we had temperatures nearing 70 degrees…. Then in May we had overnight lows in the 30s with a lot of fluctuation in between. Well, trees don’t just follow the Gregorian calendar…. They rely on weather cues.” The cycle of repeatedly producing growth for spring then enduring colder temperatures can hasten a tree’s decline.
Changes in the region’s climate have also increased the intensity of local storms and the frequency of microbursts, causing severe damage to arboreal canopies. “We’ve been pulling a lot of trees off houses these past few years, sadly, because we’re getting these windstorms,” Meyer said.
Some Other Tips
Soil compaction is another major source of root damage to trees, Meyer stresses. And, the clay-rich soils of this region are especially susceptible. Without well-aerated soil, water and nutrients can’t flow as efficiently through root systems. Meyer suggests homeowners consider his company’s product known as the Air Gun, which can help remove and replace compacted soil around root systems without the sort of damage shovels can cause.
While many homeowners try to feed their larger trees using nutrient rich tree spikes, Meyer recommends using an arborist to apply pressurized deep root feedings. This method is much more efficient in applying the nutrients directly to the roots and helps aerate the soil much more. “That’s the best way we have found over the course of our 141 years as a company to feed your trees.”
Keeping your trees well-watered, but not over-watered is another key point. An arborist can use a tensiometer to measure the soil’s dampness, but Meyer suggests a simple test. If you dig down about four inches and take a handful of soil, can it be easily squeezed into a mudball? If so, the soil has the right level of moisture.
And, how about any damages caused by the recent 17-year cicada brood? Meyer tells homeowners not to worry. While the flagging of the tree branches might look unsightly, the cicadas helped aerate the soil and their decaying exoskeletons provide healthy nutrients to tree roots. Keeping the trees well nourished, watered, and pruned is the best preventative care if you’re concerned about cicada damage.
“Trees are living beings. Much like your pets and your family members, they need checkups as well,” Meyer said.