Dallas Urban Forest Advisory Committee
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Troubleshooting Tree Problems

Hazard Trees
Trees need to be treated if they have been weakened and could present a hazard to public safety, infrastructure, or power delivery. Every tree that has a potential target within a distance equal to its height should be assessed.

Signs that your tree could be a danger include:

  1. Broken limbs over 3 inches in diameter that are lodged or hanging in the crown.

  2. Broken top or broken fork that has impacted more than 25% of the original crown.

  3. New cracks in the main trunk.

  4. Raised soil or exposed root crown.

  5. Diseased, dying, or dead portions of the crown exceeding 25% of the total.

If one or more of these signs are present, consult a professional forester, arborist, or tree surgeon immediately. Until the tree is removed or fixed, stay clear and move assets that may be a target.

People
People are by far the biggest killer of trees. Many people with good intentions love their trees to death, while others see trees as an obstacle to be removed. On large trees with significant energy reserves, damages (especially to the root system) may not be evident for up to 5 years after the impact occurs. The following are some of the main people-caused reasons for tree decline and death:

  • Construction damage often occurs to the root system as a result of compaction, trenching, soil contaminants, and erosion. A root protection zone equal to 1.25 feet for each inch in tree diameter (measured at 4.5 feet above the ground) should be established, fenced, mulched, watered, and monitored during construction activities. No activities, personnel, or equipment should be allowed in this area.

  • Trenching cuts roots limiting nutrient and water uptake and severing the anchors holding the tree upright. Tree roots extend 2-3 times the width of the canopy, radiating like spokes on a bicycle wheel, and are concentrated in the top 18 inches of soil. The closer the trench is to the trunk, the more roots will be severed. Tunneling is the best alternative. Tunnels should be located more than 18 inches deep and extend either directly under the center of the trunk or as far from the trunk as possible. If trenching is necessary, excavate the soil with an air spade and sever as few roots as possible cleanly with a saw or loppers.

  • Mechanical (weed-eater and/or mower) wounding from any source forces the tree to use vital energy reserves and provides a path for rot, insects, and disease. Protect trees with a wide mulch ring and stakes or other protective barriers.

  • Filling and grading (adding or taking away) 2 inches or more of the soil in the clay soils prevalent around Dallas can damage or kill any tree. The portion of the root system where filling or grading occurs will probably die and may re-grow very slowly. Consider a no fill or grade zone encircling the entire root protection zone for trees that are to be retained on site (see above construction bullet). Excavate the edge closest to the root protection zone using an air spade followed by severing roots cleanly with a saw. Avoid tearing or crushing roots with a bulldozer, back hoe, or similar equipment.

  • Soil additives – tree health can be affected by fertilizers, chemicals, salts, and contaminated runoff. Be careful to use only what is needed, contain applications, and dispose of substances according to instructions on the label.

Grass
Grass and trees don’t get along! Roots compete for water and nutrients, nutrient and light requirements are different, and some trees release natural chemicals which can kill grass. Oaks and walnut are particularly incompatible with grass. The best alternative to have trees and grass in close proximity is to mulch the area under the canopy of the trees and only manage the grass in areas away from trees. Weed and feed fertilizer for lawns is detrimental to tree health and chemicals that benefit grass often harm trees and vice versa. There are no green lawns in the forest.

Storms
Lightning, ice, and wind can cause serious damage to trees. Impacts may include branch breakage, root damage, leaf stripping, and stem damage. Lightning protection devices may be installed on high value trees that are adjacent to areas receiving a lot of use such as popular golf courses. Pruning can thin the crown of the tree to reduce potential wind and ice damage. One of the best defenses against storms is picking an appropriate tree for the site that will be hardy and resistant to natural occurrences.

Insects and disease
Oak wilt is one of the few diseases that can cause trees to die quickly. Oak wilt mainly affects members of the Red Oak family including Red Oak, Live Oak, Shumard Oak, and Willow Oak. Common symptoms include spring or summer yellowing or browning of leaves. Diagnosis should be left to professionals; however more information can be obtained at, Texas Oak Wilt Information Partnership website.

Mistletoe is a parasitic plant that takes its water and nutrients from the tree it is growing on. Mistletoe does some harm to the tree, but is not usually a serious threat to tree health unless it establishes a significant population and has multiple growths on main branches and the trunk. Swelling underneath mistletoe growths on main branches or the trunk can weaken the structural integrity of the tree or limb and may result in a public safety hazard. Consult a professional arborist for treatment of mistletoe.

Many insects and diseases bring about secondary impacts on trees. An initial impact such as construction damage or drought stress weakens the tree, which then attracts the insect or disease, or lessens the trees ability to resist secondary damage. On mature trees treatment options are limited and often very expensive. Consider all options, including removal, before deciding to treat an insect or disease problem. An active tree planting replacement program and maintaining a diversity of native species are good defenses against serious insect and disease epidemics.

Tips for Hiring a Tree Surgeon
Try to find a local licensed tree surgeon from the phone directory. One who is also a certified arborist is likely to bring greater expertise to the job.

Beware of unsolicited offers, bargain deals, and out-of state companies.

Never pay in advance. Pay only after the vendor has completed work to your full satisfaction. Sign a written agreement prior to allowing work to begin on your property.

Ask for certificates, proof of liability insurance, and workmen’s compensation. Phone the insurance company to confirm that current coverage is in place.

Ask for references from other jobs and check them. Get more than one estimate for the work.

Do not hire a company that recommends topping a tree.

Beware of an arborist who wants to do extensive work on, or remove living trees that appear to you to have limited damage.

Contact ISA (International Society of Arboriculture), Texas Chapter for hiring an ISA Registered Arborist.

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