General Tree Care Info

The below information includes some tips to keep your tree healthy. Unfortunately, once damage is done to a tree, it is there for the rest of its life.

What You Can Do To Protect Your Trees

  • Trim trees every 3-5 years.
  • Remove grass from around trees (this will help reduce the competition for air, water, and nutrients).
  • Install mulch under the tree canopy (this will help with soil moisture, and soil temperature fluctuations, and increase the benefits of mycorrhizae).
  • Start a Plant Health Care program (this will help increase the health of the trees and is a good starting point).
  • Winter watering for new trees and all evergreens with water and mycorrhizae
  • Deep root fertilization with major and minor elements and with mycorrhizae (to help with establishment, growth, and structure).
  • Plant new trees using the 15% rule (no more than 15% of any tree family should be planted in any location).

Tree Roots

The most common problem in landscapes is the competition for water, oxygen, and minerals from the soil. Trees and lawns serve many of the same functions and often fight for the same resources. They produce oxygen, cool the air, stabilize dust, trap air pollutants, and help control erosion. Trees provide shade for buildings in summer, and windbreaks, and provide a habitat for wildlife. Lawns provide ground cover for lower traffic areas, as well as a place to walk and play. Most tree roots are in the top 12 inches of the soil and lawn roots are in the top 4-6 inches; meaning, tree/lawn roots often occupy the same space. This results in competition over water and nutrients. Tree root functions include water, mineral conduction, food, water storage, and anchorage. Roots grow where water, minerals, and oxygen are found in the soil and allow root growth. Roots need some water and oxygen, but if soils are saturated with water, most roots will die. Because oxygen is usually located in the upper 12 inches of soil, the largest concentration of feeder roots exists in this zone. For a healthy tree, remove the grass underneath so the tree doesn't have to compete for air space, water, and nutrients. As an alternative to grass, you can add mulch.

Mower Damage

Hitting a tree with a weed whacker or mower can result in an ugly gash and can lead to disease and eventual death of the tree from girdling. The tree’s circulatory system is just under the bark, and it is responsible for transporting water and food throughout the tree. Injuries to this area interfere with plant uptake of water and vital nutrients, as well as the starches produced through photosynthesis in the leaves. Mowers and weed eaters do damage by removing patches of bark, which interferes with the circulatory process. As the roots are deprived of food, they begin to starve and function poorly -- and this leads to a stunted, unhealthy tree. As a result, the tree may decline, leaving it more susceptible to pests and diseases. The injury opens the door to fungi, which can cause wood decay and eventual tree death. If the wound completely encircles the trunk, girdling the tree, death is inevitable.

The benefits of Mulch

Trees growing in a natural forest environment utilize leaves and other fallen debris. This organic material breaks down to release nutrients back into the soil. Mycorrhizae colonies are present naturally in this soil. This environment is optimal for root growth and mineral uptake. In general, urban trees grow in poor-quality soil so we need to help them as much as we can. Applying mulch can help replicate the benefits of the forest floor while maintaining a more formal appearance.

  • Reduces soil moisture loss through evaporation.
  • Controls weeds.
  • Helps insulate soil.
  • Improves soil biology, allowing air to get to the roots.
  • Increases soil fertility. As mulch decomposes, new elements become available
  • Helps keep string trimmers and lawn mowers from doing damage to the tree trunk.
  • Provides a uniform look.

Proper Watering

Trees and shrubs have deeper, more extensive root systems than grass. Therefore, they should be watered slowly and for longer periods of time; the soil needs to remain moist for 6-12 inches deep around your tree. Remember to irrigate long and slow to get to the tree roots. If you don't water long enough, you may not provide enough water to get past the grassroots. Apply water to an area at least as wide as the tree branch spread. If your plants are showing symptoms of moisture stress (wilting, yellow leaves, and/or scorched leaves) apply more water. Add mulch and control weeds and/or grasses around the trunk to reduce evaporation and competition for water. For newly planted trees and shrubs, water frequently until the root system is established.

Remember, newly planted trees are dependent on roots within the root ball for water uptake to survive. Therefore, the most important place to check water status (water need) is in the root ball or root mass, not in the surrounding backfill soil. Until roots grow into the backfill soil, moisture in the rootball or root mass can be depleted very quickly. With temperatures hovering around 100 degrees, daily irrigation may be in order, especially for plants on open, exposed sites.

To properly water newly installed landscape plants, apply water slowly near the base of the plant and over the developing root system. Water applied too rapidly will be lost through runoff. A good rule of thumb for tree watering is 10 gallons of water for every 1 inch of tree DBH. Applying organic mulch over the tree's new planting site will help conserve moisture in the soil. Wood chips will also help water infiltrate the soil rather than become runoff.

Mycorrhizae

Mycorrhizae are a class of fungi that thrive in a symbiotic relationship with the root of the tree. Mycorrhizae fungi colonize the root system of the tree, forming a biological link between the root and the soil. The fungus grows into the root and out into the soil. The root fungus in the soil absorbs water and nutrients from the soil and conducts them back to the root. The sooner mycorrhizae forms, the better it is for the plant.

Pine Needle Drop

Pine trees display fading yellow or brown needles mostly as part of a natural shedding process. Evergreens shed their older, interior needles as part of an annual growth cycle. Needles on the lower portions of the crown or closest to the trunk are most commonly shed, but trees stressed due to drought or root damage may shed more needles to keep the tree in balance with its root system. Soon-to-be-shed needles are typically yellow first, followed by a reddish-orange or brown color before dropping off. Trees can have varying levels of needle shed, even within the same property or general area. Most are simply going through a natural shedding process. The shedding of needles typically happens in September, October, and early November.

Emerald Ash Borer (EAB)

EAB attacks and kills all varieties of ash trees. Trees must be treated for EAB before symptoms are noticed in order to preserve trees. EAB larvae live under the bark of the tree and create tunnels through the vascular system of the tree. This system is responsible for moving water from the roots of the tree to its crown. Damage to the system will prevent this movement of water to the crown of the tree, ultimately causing the tree to die in less than four years. EAB must be treated before there are symptoms, otherwise, there is likely already irreparable damage to this system, making the tree weaker. EAB is now considered to be the most destructive tree insect - killing over 40 million ash trees nationwide - with the potential to kill 867 million trees in Minnesota alone. EAB is invading trees everywhere and can only be stopped through preventative measures.

Cytospora Canker infection

This disease affects many species of trees and shrubs in Colorado ( including aspen, ash birch cottonwood, poplars, apple, cherry, peach, plum, birch, willow, honeylocust, mountain ash, maple, spruce, and elm.). are under stress. The fungus attacks trees that are injured, weak or stressed. The fungus grows in the living bark (phloem) and wood (xylem) and kills the plant by girdling the infected area above the canker.

Trees affected by drought, late spring frosts, insects, sunscald, herbicides, root damage, or mechanical injury are susceptible to Cytospora infection. The disease especially likes trees with root damage.. Because this canker occurs on a weakened host, the primary method of control is to prevent stress on the tree. With a good PHC plan to increase tree health and vigor, and sanitation pruning.

Emerald Ash Borer (EAB)

EAB attacks and kills all varieties of ash trees. Trees must be treated for EAB before symptoms are noticed in order to preserve trees. EAB larvae live under the bark of the tree and create tunnels through the vascular system of the tree. This system is responsible for moving water from the roots of the tree to its crown. Damage to the system will prevent this movement of water to the crown of the tree, ultimately causing the tree to die in less than four years. EAB must be treated before there are symptoms, otherwise, there is likely already irreparable damage to this system, making the tree weaker. EAB is now considered to be the most destructive tree insect - killing over 40 million ash trees nationwide - with the potential to kill 867 million trees in Minnesota alone. EAB is invading trees everywhere and can only be stopped through preventative measures.

How to Trim a Tree

  • Any work done on a tree should be done for a reason
  • Trim trees so the natural form and shape of the tree are maintained
  • Remove dead, dying, diseased and decayed areas
  • Remove obviously weak, broken, overlapping, or rubbing branches
  • Provide street, sidewalk, building, and power line clearance
  • Water suckers should be left throughout the tree to encourage trunk taper
  • Remove suckers at the base of the tree, which only steal energy from the tree

Trimming Evergreen Trees

  • Remove dead, dying, diseased, decayed, and obviously weak branches up to 10-30 feet high, keeping in mind that Evergreens will lose some of their inside needles
  • Remove objectionable branches that cause crossing or rubbing to allow for air movement
1
2

Branch cutting / limb removal uses a 3-step process
The final cut should be done near the Bark Branch Collar

Trimming Deciduous Trees

  • Trim off any suckers growing at the base of the trunk.
  • Suckers at the base of the tree only steal energy from the tree, and usually these suckers are a wild stock
  • Remove all the dead or dying branches
  • Remove any damaged or weak branches, including storm damage
  • Prune out unwanted, overlapping, rubbing, or hazardous branches
  • Provide lifting for street clearance of 13’ 6”
    Lift from sidewalks 8’
  • Provide building clearance
  • Provide electrical wire clearance
  • Remove damaged areas caused by squirrels

Tree trimming

Training Prune

Training pruning consists of selecting the central leader and removing the competing leaders. Then, select the lowest permanent branch, select the main scaffold branches, and cut back the competing branches. Also, remove dead, diseased, and dying branches.

Classe 1

(Small to Medium Trees from 5ft to 25ft)
Fine Pruning Shall consist of removing dead, dying, diseased, interfering, objectionable, and weak branches and selective thinning to lessen wind resistance. Elevate 3-5' over structures and to city code over street/sidewalk. Deadwood up to 1/2" in diameter may remain within the leaf area)

Class 2

(Medium Trees 26ft to 50ft)
Medium Pruning shall include removing dead, dying, diseased, interfering, objectionable, weak branches and selective thinning to lessen wind resistance. Elevate 3-5' over structures and to city code over street/sidewalk. Deadwood up to 1" may remain in the leaf area.

Class 3

(Large Tree's 51ft and up)
Large Pruning shall remove dead, dying, diseased, interfering, objectionable, and weak branches 2" in diameter or more. Elevate 3-5' over structures and to city code over street/sidewalk.

Tip Prune

Remove select branches to reduce weight at the end of the limb.

Mitigation Prune

Trim branches six to eight feet from the ground. (Ladder fuels are low-hanging branches of trees. They allow flames to “climb” into tree canopies). Remove ladder fuels (lower branches) from coniferous trees to protect tree canopies from wildfire. Trim branches six to eight feet from the ground on mature pines and Spruces. Remove dead trees standing and on the ground.

Tree Removal

Remove the tree to as close to grade as possible. A stump of 1”-12” could remain.

Shrubs Trimming

Hand Prune

Shrubs and Bushes are trimmed with hand-powered pruners to reduce their size and keep their natural form.

Rejuvenation Prune

Shrubs and Bushes are cut to 6-12" from grade level to promote new growth.

Renewal Prune

Remove old stock (larger branches) to promote new growth.

Shear

Shear Shrubs and Bushes with a gas-powered hedge trimmer to create a uniform appearance.

Stump Grinding

It will meet Denver's guideline minimum of 6" DEEP; an extra charge will apply for deeper stump grinding.

Plant Health Care (PHC)

Spring Deep Root Fertilization

A formula of micronutrients and slow-release nitrogen to promote growth and foliage production. Beneficial ectomycorrhizal Fungi are added to encourage root hair development.

EAB

Trunk injection using Emamectin Benzoate to prevent & control Emerald ash borer and native borers. This treatment is performed 1x every 2 years.

IPS Bettle Treatment Spring

Timed preventive spray against IPS Engraver Beetle in Spring. IPS has multiple generations and often requires a second spray in July or August.

IPS Bettle Treatment Summer

Timed preventive spray against IPS Engraver Beetle in Late Summer for continued protection through the remainder of the year.

General Insect

Controls insects like aphids, mites, leafhoppers, and caterpillars for a period of 3-4 weeks. 2-3 sprays per year are often necessary for insect suppression.

Winter Water all Evergreens and newly planted trees.

Evergreen trees, continue to photosynthesis thought the winter. Durning transpiration and respiration there needles expand water Without additional water the needles turn reddish or brown around the edge and branches can die back.This is know as winter burn. Winter burn can kill trees.

Newly planted trees are most susceptible to winter drought injury. Trees generally take one year to establish for each inch of trunk diameter. For example, a two inch diameter (caliper) tree takes a minimum of two years to establish under normal conditions. Apply water to the dripline.

Winter Water

Trees and shrubs have more profound, more extensive root systems than grass. They should be watered slowly and for more extended periods of time; the soil needs to remain moist for 6-12 inches deep around your tree. Remember to irrigate long and slow to get to the tree roots. If you don't water long enough, you may not provide enough water to get past the grassroots. Apply water to an area at least as wide as the tree branch spread. Apply more water if your plants show moisture stress symptoms (wilting, yellow leaves, and/or scorched leaves). Add mulch and control weeds and/or grasses around the trunk to reduce evaporation and competition for water. Water frequently for newly planted trees and shrubs until the root system is established. Remember, newly planted trees are dependent on roots within the root ball for water uptake to survive. Therefore, the most important place to check water status (water need) is in the root ball or root mass, not in the surrounding backfill soil. Until roots grow into the backfill soil, moisture in the rootball or root mass can be depleted very quickly. Daily irrigation may be in order, with temperatures hovering around 100 degrees, especially for plants on open, exposed sites. To properly water newly installed landscape plants, apply water slowly near the base of the plant and over the developing root system. Water applied too rapidly will be lost through run-off. A good rule of thumb for tree watering is 10 gallons of water for every 1 inch of tree DBH. Applying organic mulch over the tree's new planting site will help conserve moisture in the soil. Wood chips will also help water infiltrate the soil rather than runoff. During extended periods of high heat, you may need to water more frequently and check the soil and water appropriately.

Tree Planting

Tree and Shrub planting will meet industry standards. Using the Urban Forest Age and tree Spices

The 10-20-30 rule is a guideline for managing tree diversity in urban forests. It states that a city's tree population should include no more than:

  • 10%: Of any one species
  • 20%: Of any one genus
  • 30%: Of any one family

Tree and Shrub planting will meet industry standards

Tree Wrap

Tree wrap is used to protect young, thin-barked trees during the winter months. Wrapping trees helps protect against sunscald and frost cracks, both of which are temperature-related. Wrapping is usually done in November.

Tree unwrap

Removed in early spring (mid-April). Tree wrap should not be left on all year.

Bolts

Bolting rods are often used to support trees with included bark or trees with splitting limbs by bolting them together. Installing rods to offer additional support does NOT guarantee that the tree will not fail in the future.

Mulch

  • Reduces soil moisture loss through evaporation
  • Controls weed
  • Helps insulate soil
  • Improves soil biology, allowing air to get to the roots
  • Increases soil fertility as mulch decomposes new elements that are available.
  • It helps keep string trimmers and lawnmowers from
  • damaging the tree trunk.
  • It gives a uniform look

Applying mulch can help replicate the benefits of the forest floor while maintaining a more formal appearance. Trees growing in a natural forest environment utilize leaves and other fallen debris. This organic material breaks down to release nutrients back into the soil. Mycorrhizae colonies are present naturally in this soil. This environment is optimal for root growth and mineral uptake. Urban trees grow in poor-quality soil, so we need to help them as much as possible.

Tree inventory updates

Field technicians who assess individual trees on a set of criteria complete a tree inventory on the ground and plot their location. A tree inventory provides an exact count of trees in a defined area and can provide detailed information on the condition of each tree, too. Some of the critical insights of a tree inventory are:

  • Species: composition and age diversity of trees
  • Diameter: at Breast height. (DBH)
  • Condition: A way to measure the urban forest suitability for preservation is “low/dead,” “fair,” “average,” or “high.” Suitability for preservation considers the tree's health, age, and structural condition. As well as the tree’s potential to remain an asset to the site for years to come
  • Vigor: Looks at how well the tree appears to be growing, overall health, trunk flare, and leaf scars. Terminal bud (aka bud-scale) scars provide an excellent way to leaf through a tree’s health records going back 5 to 10 years. Bud-scale scars form when a terminal bud starts to grow in springtime, leaving behind a ridge of bark around the twig. You can look down the twig toward its parent stem and usually find some terminal bud scars. The space between each scar is called a node, and it represents the growth from a particular year. It acts as a ruler for arborists to see how well your tree is growing.
  • Target: A target is something under the tree. This includes buildings, parking, traffic, pedestrians, recreation, landscape, hardscape, and utility lines. The higher the score, the greater the chance of a tree failure damaging the target. Sometimes, you can move the target, and the target score can move.

Tree inventories provide the data needed for short/Long-term tree population management, such as existing tree maintenance needs, new tree plantings, tree removals, and other day-to-day forestry operations. It can help identify high-risk trees and routine maintenance needs. And help with predicting PHC for pests/diseases.

Questions and Answers about the Emerald Ash Borer

The emerald ash borer is a type of beetle that develops under the bark of ash trees. Its scientific name is Agrilus planipennis. It is a type of beetle in the family Buprestidae, which are known as metallic wood borers in their adult form and flatheaded borers in the immature stage.

Yes. There is no natural control to keep the insect in check.The larval stage of EAB feeds under the bark of trees, cutting off the flow of water and nutrients. Infested trees gradually die over a period of approximately two to four years. Right now the only way to keep your tree alive is with a preventative Spray.

The natural range of the emerald ash borer is eastern Russia, northern China, Japan, and Korea. Before June 2002, it had never been found in North America.

Trees of all sizes can be attacked, from 1/2-inch saplings to the largest, most mature trees.

Answers: We don't know for sure, but it most likely came in ash wood used for stabilizing cargo in ships or for packing or crating heavy consumer products.

In North America, it has only been found in ash trees (Fraxinus species).
Trees in woodlots as well as landscaped areas tend to be most affected. Larval galleries have been found in trees or branches measuring as little as 1 inch in diameter. All species of North American ash appear to be susceptible. Ash trees commonly grow in Colorado (include green ash (Fraxinus pennsylvanica) and white ash (F. americana). Both are highly susceptible to emerald ash borer.

No. Despite the name, mountain ash (Sorbus species) are very different types of plants and are not attacked by emerald ash borers.

The adult beetle is dark metallic green in color, 1/2 inch long and 1/8 inch wide. The larvae, which are found under the bark, are a type of flathead borer that is pale-colored, has an elongated body, and a slightly flattened area behind the head. There are numerous sites where one can find excellent images of emerald ash borer. Several are accessed through the National Emerald Ash Borer information website:

This insect is very difficult to detect because it is under the bark, but here are some signs to look for.

  1. Branches without any leaves, especially at the tops of ash trees.
  2. Vertical splits in the bark exposing S-shaped tunnels.
  3. Wild leafy branches (new growth) sprouting from the trunk at mid-way of the tree.
  4. D-shaped exit holes.

If ash trees display multiple symptoms, it is likely an indication of a multi-year emerald ash borer infestation.

  1. Imidacloprid: Is a soil injection or drench done in Early / mid spring to mid/late fall. Best done on trees from 1 DBh to 10 DBH. This is done every year.
  2. Emamectin benzoate: This is a trunk injection done from Mid- to late spring after trees have leafed out. Best done on trees 10 DBH (diameter at breast height) and bigger. This is done every 2 years.

Yes. Please check with your city for more info.

EAB attacks and kills all varieties of ash trees. EAB must be treated before there are symptoms, otherwise, there is likely already irreparable damage to this system, making the tree weaker. Causing the tree to die in less than four years. EAB is now considered to be the most destructive tree insect - killing over 40 million ash trees nationwide - with the potential to kill 867 million trees in Minnesota alone. EAB is invading trees everywhere and can only be stopped through preventative measures.