Tennyson Park HOA - Tree Inventory Recommendations Report DRAFT

Tennyson Park Homeowners Association Tree Inventory and Recommendations Report Produced By:

Plan-It Geo, LLC 5690 Webster Street Arvada, CO 80002 Introduction Trees in Tennyson Park HOA add aesthetic appeal, increase property values, and provide many environmental benefits like clean air and water. Trees also require maintenance, management, and care to ensure that each tree is receiving the proper resources in Colorado’s dry climate. The first and most important step in urban tree management is to understand the composition, condition, and threats to the trees being managed.

Plan-It Geo conducted a neighborhood scale tree inventory, recording the location and ecological information This image from the Tennyson Park HOA shows the stark fall color about all street, exterior landscape, contrast of green ash (Fraxinus pennsylvanica - left) and white ash and cottage home front yard trees in (Fraxinus americana- right). the Tennyson Park HOA. This information can be used to inform residents and managers of short and long term threats, and establish priorities for maintenance, and provide an estimate of the total benefits provided by the HOA’s trees.

This report describes the methods used to conduct the tree inventory, presents maps, graphics and text describing the major findings, and provides general tree care recommendations based on the trees located within the HOA.

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Tree Collection Methods The inventory was conducted by Plan-It Geo’s arborists (certified by the International Society of Arboriculture (ISA)) using the Tree Plotter, web based application (see Tree Plotter description below).

Trees, vacant planting sites, and stumps were recorded (planting sites were only considered if there was an empty vegetated planting strip between the sidewalk and the street). Each tree was individually inspected for site and root quality, trunk and branch defects, and evidence of pest damage. The inventory took place prior to “leaf-out” so leaf quality could not be assessed. The following list details specific fields recorded for each tree: Species - Common name and genus of each tree Size (DBH) – Girth of the tree’s main trunk in inches (“diameter at breast height”) Condition - Overall condition of the tree into ISA categories Maintenance Need - Most prominent or priority maintenance need Observations - Defects or possible detriments to the tree Property Address - Address the tree lies on or is in proximity with, where applicable Grow Space – Location of each tree relative to the home (Cottage Front Yard, Cottage Street, Exterior Landscape, or Other) Longitude/Latitude – “X, Y” location of each point Notes - other notes collected by the arborist as necessary

The completed inventory consists of 250 trees, 8 vacant planting sites, and 1 stump (see Inventory Map below). Relative location of the trees was fairly evenly distributed with slightly more trees located along the streets of cottage homes (“Cottage Street” – 30%).

The Tree Plotter Dashboard provides an organized, interactive summary of the data fields collected at each location. The Tennyson Knolls dashboard can be accessed through Tree Plotter or by clicking here.

Some inventory results viewable in Dashboard are presented below.

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Tennyson Park Tree Plotter Plan-It Geo’s Tree Plotter software app, is useful for collecting as well as displaying and summarizing the inventory information (for more information about Tree Plotter in general, see our webpage at http://www.planitgeo.com/#!plotter-application/cgnl). As part of this project, all Tennyson Park residents, managers and guests can view the information collected by using the guest access at the following web address: pgmobile.planitgeo.com/TennysonKnolls. Some basic inventory results are presented in the next two pages through screenshots of Tree Plotter Dashboard but all are encouraged to visit the interactive website. The Tennyson Park Tree Plotter will be available until December 1, 2014.

Tennyson Park Tree Plotter Dashboard results (image 1 of 3). Interactive boxes at top illustrate counts by user selections. A few selections are provided here, but residents and managers are encouraged to visit the web tool to interactively investigate the inventory results. Pie charts below illustrate preset distributions by percentage of the total tree count.

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This preset chart available in Dashboard (image 2 of 3) illustrates species distribution by stacked diameter at breast height (DBH) range. With more than 45 individual trees, Lindens make up the majority of tree species in the HOA (most Lindens are between 6-12 inches DBH), while most large trees (dark orange) are crabapples and Austrian pines.

The majority of trees inventoried were in good condition, while the most common species in critical condition were Lindens. Note that 100% of green ash trees are in either fair or critical condition.

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Major Findings and Recomendations Tree Observations This section explains some of the observations of greatest concerns to the inventory arborist. Ecological concepts are briefly introduced to convey understanding of why the listed observations are important.

These observations represent good areas to focus maintenance needs and attention.

Poor Root System Tree roots absorb water and nutrients vital for grow and maintenance, support the entire trees upward structure, and provide valuable storage medium for sugars and nutrients stored over winter. 

51 of the 250 (20.4%) trees inventoried have poor root system.

Root systems of about 20% of observed trees were exposed, compacted, or displayed signs of girdling the vascular tissue of the tree. The main factor contributing to exposed roots is overwatering in the area’s poorly drained soils. Too much water reduces needed air in the soil, causing roots to rise to the surface to acquire more oxygen. Overwatering also encourages runoff, leading to soil erosion around the base of the tree. Exposed root systems are more susceptible to compaction from pedestrian traffic, lawnmower, and frost damage.

This Linden has a severe girdling root that is close to choking off the vascular tissue of the tree.

The larger Maples in the neighborhood had exposed root systems that are being damaged by mowing equipment.

Early root structure issues can be a result of planting a tree in the wrong depth of soil.

Solutions for Poor Root Systems The most important and effective step in preventing poor root structure is to ensure proper installation procedures are utilized during the planting process. Tree selection, proper planting depth, back fill medium and watering regiment must be considered an executed appropriately to ensure the greatest chances of success. After establishment periodic mulching has many advantages that increase soil Tennyson Park HOA Tree Inventory and Recommendations Report – Plan-It Geo

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aeration, reduce damage to shallow roots from pedestrian traffic, and prevent mechanical damage to the main stem from lawn mowers and other maintenance activities.

Trees Needing Removal and Replacement Maintenance Overall, the tree population in Tennyson Park is still young and requires less maintenance than a mature forest with high canopy cover; however, there were still a few trees that require maintenance.  

15 of the 250 (6%) trees inventoried require maintenance.

7 of the 15 were marked for removal.

Trees selected for removal should be immediately addressed to minimize risks to property and human safety. Most trees marked for removal are young and small, reducing overall risk due to small size, lack of maintenance can cause liability and monetary issues.

The removals were considered to be trees that will not live through the existing conditions no matter how much care is provided to the tree (for example, severe rot/decay paired with root structure defects). Although many of the trees with poor root systems are not marked for removal now, they will need to be monitored and checked every few years to monitor the trees reaction to these current conditions.

This chart created from in the Tennyson Knolls Tree Plotter illustrates that the7 trees marked for removal range between 3 and 12 inches in stem diameter.

Solutions for Maintenance Removals/Replacement Maintenance removals of these 7 trees is straight forward: (1) Remove the tree utilizing trained tree care professionals, (2) grind the stump (where necessary), and (3) replant with appropriate and diverse species (see The Front Range Tree Recommendation List, developed by Colorado State University, can be accessed at: http://www.ext.colostate.edu/pubs/garden/treereclist.pdf).

This Linden was marked for removal due to the amount of heartwood rot occurring inside the tree.

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Pest Problems The primary pest of concern in the Tennyson Park HOA is the Lilac Ash Borer (LAB; Podesesia syringae), illustrated to the right. Most damage is caused by the borer’s larvae which feed on the tree’s main vascular tissue beneath the bark. In spring, the insects emerge by chewing large D-shaped holes through the bark. Adults fly, mate, then lay eggs on the trunks and stems of ash trees. Once eggs hatch, the larvae bore beneath the bark surface to renew the life cycle. 

33 of the 250 (13.2%) trees inventoried in the HOA were Ash including 19 trees that had visible evidence of Lilac Ash Borer infestation.

The Lilac ash borer eats away at the vascular (sapwood) tissue of the ash tree and emerges from the tree as an adult moth (pictured upper right) in the spring.

Evidence of LAB infestation includes loss of plant vigor and mortality of branch tips, entire stems, and occasionally the entire tree. Only rarely do LAB infestations result in tree mortality, most often when other environmental conditions cause stress on the tree. Often confused with Emerald Ash Borer (EAB), the LAB leaves behind larger, more ovate exit holes (see Call-Out box below for more information on EAB).

Information on the Lilac Ash Borer can be found in the appendix of this report and at: http://extension.usu.edu/files/publications/factsheet/lilac-ash-borer10.pdf Solutions for Pest Problems

There are multiple options for mitigating the impact of the LAB. The first two are generally good practices regardless of insect presence while the third option is targeted at protecting trees specifically from the LAB: 1. Maintain healthy growing conditions for the trees: Irrigation, proper mulching, good growing space for roots, and possibly fertilization is the best defense against LAB, other borers (except Emerald Ash Borer), and tree pests in general.

2. "Renewal pruning" effectively removes older, lower branches that are typically the most susceptible to borer populations. Proper pruning will also ensure that the trees' “power supply” (branches and leaves) is working at full capacity.

3. Insecticides can be applied to the trunk and branches to kill newly hatched larvae before they enter the bark. There are a few recommended consumer-level insecticides that can be useful.

The application should take place in the spring, as the adults are emerging from the trees at the end of their life cycle. It is recommended that any chemical application be completed by tree care firm that specializes in chemical use and application.

The treatment described above should be considered only for exceptional or high-value trees. The Lilac Borer is a moth that is native, and pervasive in Colorado. It is likely to infest any and all ash trees that are "stressed". Treating one tree probably won't impact the likelihood of others around it being infested.

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The Emerald Ash Borer (EAB) introduces a new dynamic to the decision-making process for enhancing and extending the life of your ash trees (see the Call-Out box below). While both LAB and EAB are both borers that primarily infest ash trees, their impacts are quite different:  The most important difference is that the LAB can infest a tree for many years only causing partial loss of limbs and vitality. EAB infestation will eventually lead to mortality, without treatment.  Treatments for each insect are exclusive and do not significantly impact the life cycle of the other.  Lilac borer is more likely to infest weak or stressed trees, while EAB is not selective and will infest and kill even healthy, vigorous ash trees.

Our recommendation is to focus resources on removal and replacement of ash trees over a scheduled and staggered period of time, to avoid both extreme costs to managers for tree removal and severe loss of ecological function, property values, and aesthetics for residents.

Ash Tree Population Another removal/replacement issue facing the neighborhood is centered on the Green and White ash population. 58% of the Ash Trees are showing visible signs of a Lilac Ash Borer infestation while 100% of ash will be susceptible to Emerald Ash Borer (EAB) infestations within the next decade. There are many options for treatment and removal of ash trees being implemented around the state (see ColoradoEAB.gov for more information).

Tennyson Knolls HOA Tree Inventory Species

100% of ash trees will be susceptible to EAB and tree mortality.

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Green Ash

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White Ash

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All Other Species

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Solutions for Ash-Specific Removals/Replacement Due to the destructive nature of EAB, a time will come to decide whether each ash tree should be removed or treated annually for as long as it is desirable to keep the tree alive. These two options can be used in concert to stagger high one-time cost of removals, while phasing out persistent costs (treatment) over time.

An example treatment plan:  Years 1-3 – Treat 50% of most desirable ash trees, with 50% removal. Three years after infestation, ash trees become very hazardous by dropping limbs.  Years 4-6 – Drop treatment of 25% of original desirable trees, while phasing in more removals.  Years 7-10 – Drop treatment by 10% per year while increasing removals.

The Colorado State Forest Service does not recommend EAB treatments for Arvada at this time. Timing of treatment schedules should be determined through a trusted local tree care provider, or through regular monitoring of the EAB Colorado website.

For the Tennyson Park HOA, we recommend a three phase ash removal/replacement and treatment plan: 1) Removal and Replacement of all poor and critical ash trees.

These ash trees are not worth the cost of protection and/or treatment from existing chronic health defects and are likely to decline prior to arrival of EAB. 2) Removal and Replacement of young ash trees The cost for removing young ash trees is far less than for a tree that has reached maturity.

3) Protection of good condition/mature ash trees Established, mature and healthy ash trees provide many more benefits to the residents of Tennyson Park than small, stressed trees. If the HOA decides to preserve or extend the lives of these trees (see the “Managing EAB Decision Guide” on the EAB Colorado website), they will needed to be treated for EAB in accordance with Colorado State Forest Service guidelines. If these trees survive the next decade, they will need to be treated for EAB on an annual basis.

The most effective way to mitigate the threats and costs associated with EAB and threats to forest health is to plant diverse and appropriate tree species at every site. The 10, 20, 30 rule is general guidleline followed by urban forest managers and scientists. The rule states that, within any tree “population” (such as a block, a neighborhood, or an entire city), no more than 10% of trees should be the same species, 20% from the same genus, and 30% from the same family. The Front Range Tree Recommendation List, provides updated and extensive tree planting recommendations and can be accessed at: http://www.ext.colostate.edu/pubs/garden/treereclist.pdf

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Emerald Ash Borer (EAB) Emerald Ash Borer (EAB) is an extremely destructive insect that will likely eventually cause the mortality of greater than 95% of all untreated ash trees in Colorado. EAB was discovered in the city of Boulder last September. No one really knows when EAB will spread to a new city, but most forestry professionals and scientists agree that it will eventually spread prolifically across the Front Range.

The Colorado State Forest Service, Colorado Department of Agriculture (CDA), and U.S. Department of Agriculture Animal and Plant Inspection Service (APHIS) have been working in concert with local forestry professional and municipal managers to take steps toward mitigating the threat in Colorado and surrounding states.

A compilation of locally significant resources about EAB can be found at EABcolorado.gov, including the EAB quick guide, illustrated below.

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Appendix A comparison of Lilac Ash Borer, and Emerald Ash Borer, by Dr. Whitney Cranshaw.

Lilac/Ash borer and Emerald ash borer – How do controls of these two insects overlap?

With the establishment of emerald ash borer (EAB) in a part of Colorado there are now two wood boring insects that will be commonly countered – EAB and the lilac/ash borer.

This is a cause of some confusion as there are some similarities, but also some important differences in the life history and habits of these species and in the way they are managed.

A Comparison of Life History and Habits The lilac/ash borer (Podosesia syringae) is the larva of a type of moth (i.e., a caterpillar), specifically a type of clearwing borer (Lepidoptera: Sesiidae). It is native to North America and is mostly damaging to trees in stressed sites, such as along streets and parking lots. White ash is somewhat more susceptible than green ash.

The emerald ash borer (Agrilus planipennis) is the larva of a type of beetle, specifically a type of beetle known as a “metallic wood borer” in the larval stage and a “metallic wood borer in the adult stage (Coleoptera: Buprestidae). It is native to Asia and is a highly aggressive borer; although stressed trees may be more susceptible and decline more rapidly from infestation, all ash trees can be killed regardless of original condition.

Green ash is somewhat more susceptible than white ash.

Lilac/ash borer is one of the earliest wood boring insects to be active in the growing season, with adults often beginning to emerge from trees in late April. Eggs are laid on the bark surface and egg laying is concentrated on the lower trunk. Most egg laying occurs in May and early June, with the egg laying and egg hatch period largely concluded by the middle of June.

Emerald ash borer is somewhat later in emerging from trees. It is likely emergence will usually begin in early May, but emergence may extend for a couple of months. After emergence the adults have a period when they move to the crown of the tree where they feed on leaves as eggs mature. Females then begin to lay eggs, which are laid on the bark surface, and egg laying can occur on the trunk and limbs throughout the tree.

Most egg laying likely will occur from late May through early July, with the egg laying and egg hatch period largely concluded by mid-late July.

After egg hatch the larvae of the lilac/ash borer tunnel through the bark and feed in the interior of the tree. They may feed under the bark, where they can produce irregular gouging wounds. Also larvae do considerable amounts of internal tunneling, particularly Tennyson Park HOA Tree Inventory and Recommendations Report – Plan-It Geo

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at the base of the tree, which can riddle the trunk and affected branches. External symptoms may appear in the form of deformities of on the trunk and branches where extensive injuries occurred under the bark and some epicormic branching is not uncommon.

After egg hatch the larvae of the emerald ash borer tunnel through the bark and feed in the interior of the tree. They do almost all feeding just under the bark, making meandering feeding tracks that girdle the tree. External symptoms often are a progressive overall thinning of the canopy of the tree and some epicormic branching may occur.

A Comparison of Management Lilac/ash borer is easily managed by use of a spray of insecticide that is applied to the trunk and lower branches. The insecticides used are either some persisting pyrethroid (e.g., permethrin, bifenthrin) or chlorantraniprole (Acelypryn), all of which have excellent ability to control young caterpillars upon contact. Sprays are optimally applied either immediately before or coincident with the time when eggs are beginning to hatch.

There are several means to control emerald ash borer, which are summarized in the document Control Options for Emerald Ash Borer in Colorado (http://bspm.agsci.colostate.edu/files/2014/02/EAB-control-options-February-11.pdf ).

Almost all involve use of insecticides that move systemically in the plant and are applied to target the adults when they feed on leaves before laying eggs and the young larvae as they begin to feed underneath the bark. Most widely available, easiest to apply, and least expensive is a soil application of imidacloprid. Other common EAB treatments include a trunk spray of dinotefuran, and trunk injections of either emamectin benzoate or azadirachtin. Additional treatments that can be used for EAB control include trunk injected imidacloprid, soil applied dinotefuran, or whole tree sprays with persisting pyrethroid insecticides.

The trunk spray of a persistent surface applied treatment typically used for lilac ash borer control is not appropriate to control emerald ash borer. Although these insecticides (at least permethrin and bifenthrin) can kill emerald ash borer upon contact, when used for lilac/ash borer control they are applied a bit too early for EAB control and are not applied to the whole canopy.

Whole tree sprays of persisting pyrethoid insecticides can control EAB, but to do this reliably the first application would best be made a bit later (e.g . midMay) and then reapplied a second time 4-6 weeks later. If done in this manner then these treatments may effectively kill adults on foliage and kill larvae as they hatch from eggs on the surface. However, these whole tree sprays are not generally used for EAB control as they require two annual applications, require whole tree spraying with all its attendant Tennyson Park HOA Tree Inventory and Recommendations Report – Plan-It Geo

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problems (e.g., drift, greater effects on non-target species, restrictions with wind conditions), and are more costly than the systemic insecticide options.

Imidacloprid soil treatments (soil drench, soil injection) or trunk injections used for EAB will not be effective against lilac/ash borer. Most fundamentally this is because the active ingredient, imidacloprid, is not very effective against larvae of moths – and lilac/ash borer is the larva (caterpillar) of a type of moth. Effective use of imidacloprid for wood boring insect is largely restricted to beetle larvae of the flatheaded borer family – such as bronze birch borer and emerald ash borer.

The dinotefuran trunk spray used for EAB control does not make any label claims for control of lilac/ash borer and there is no evidence that it controls this insect. That being said, dinotefuran does have some activity against caterpillars and the timing of the treatment does coincide well with the most susceptible stage of lilac/ash borer (newly hatched larvae). Further study may show that this treatment has some ability to control both species – or it may not. Until this is demonstrated the dinotefuran trunk spray cannot be considered effective for control of lilac/ash borer.

The azadirachtin trunk injection used for EAB control does not make any label claims for control of lilac/ash borer and there is no evidence that it controls this insect. That being said, azadirachtin does have some activity against caterpillars and the timing of the treatment does coincide well with the most susceptible stage of lilac/ash borer (newly hatched larvae). Further study may show that this treatment has some ability to control both species – or it may not. Until this is demonstrated the azadirachtin trunk spray cannot be considered effective for control of lilac/ash borer.

The emamectin benzoate trunk injection used for EAB control does include label claims for control of clearwing borers such as lilac/ash borer and there is good evidence that it incidentally does control this insect when used for EAB control.

Whitney Cranshaw Colorado State University draft

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