Category “Uncategorized”

MATURE TREES – ASSETS OR LIABILITIES?

Tuesday, 16 August, 2011

Mature Trees - Assets or LiabilitiesElizabeth Davison, Consulting Arborist, co-chair ACTC Annual Conference

The tree is huge, with spreading branches that cover the whole property. The trunk is sculptural, the root flare picturesque, and the foliage gives welcome shade. Birds nest in the branches and lizards run up and down. Ancient trees evoke feelings of peace and wonder.

But the arborist thinks the tree should come down – “Better safe than sorry.” Is this what should happen? How do we evaluate the health and structure of old trees?

Stately trees of a “certain age” are thought of in many ways. We call them Veteran Trees, Ancient Ones, Valuable Assets, Historical Witnesses, or Dangerous Liabilities. Our point of view reflects both our knowledge and also our lack of knowledge. Although we love the idea of an old tree supporting decades of wildlife and enduring through generations, the fact is that old trees present a unique set of challenges for the arborist, particularly in cities and towns.

As trees age, their vigor and incremental annual growth begin to slow. Foliage can begin to die back as the tree allocates water and minerals to maintenance or defense at the expense of growth. Wound response can take longer and use valuable resources. Organisms that recycle dead wood can establish themselves on old bark or root flares. The interior of branches and trunks can develop cavities that can compromise structural integrity. For these reasons, mature trees take thoughtful evaluation and special care.

Is there recent research on tree health and aging? Do we know all there is to know about tree risk assessment? Are we prepared to work safely in older trees? Do our customers listen to lawyers instead of scientists?

Coming up on September 23, the Arizona Community Tree Council’s Annual Conference has as its theme “Nurturing Our Natural Heritage: Developing and Caring for Mature Trees.” The event will be held at the Prescott Resort and Conference Center. Mark your calendars to attend and learn from some of the region’s experts. (see the ACTC web site for more information)

The Keynote Speaker for the ACTC Conference will be Nelda Matheny, Founder and President of HortScience, Inc. Nelda is a world-class writer, tree advocate, and creative researcher who has agreed to give two presentations on mature trees. Her first talk will be “Aging Trees: An Overview of What We Know”, and the second is “What’s New: ISA’s Best Management Practices/ Tree Risk Assessment”. All arborists in the region should plan to come learn from a respected member of the International Society of Arboriculture. (To hear Nelda talk twice in one day is worth the price of admission, in my opinion!)

To address problems that large trees have with insect and diseases, Bob Celaya from USFS will speak on ‘Forest/Woodlands Insects and Disease’ and Peter Warren from Pima County Cooperative Extension will speak on ‘Insects in Trees’. Tree failures and how they are recorded will be covered by Kathryn Hahne, Certified Arborist with Pima County Cooperative Extension.

Large trees can give us clues to fire history, and we want to protect our properties from increasingly-common summer wildfires. We are fortunate to have Cliff Pearlburg from the Arizona State Land Department speaking on ‘Firewise Landscapes’, and Rex Adams from the UA Laboratory of Tree Ring Research explaining how tree rings in ancient trees can teach about fires in the past.

Working in older trees can prove to be a safety challenge. Juan Barba, Consulting Arborist will be demonstrating safety techniques, and John Eisenhower of Integrity Trees will show how root excavation can expose girdling roots that can cause trunk instability. There will be a program on chain saw safety, too.

We’ll also have Paul Chambers of Australian Outback nursery speaking on trees from Australia, Cado Daily from Cochise County cooperative Extension explaining key points when designing water catchments for trees, and an overview of declining tree health in cities with Dr. Chris Martin of ASU.

In addition, an entire track of qualified speakers will give the candidates for the ISA Certification Exam a chance to review all domains. Speakers will spend the whole day reviewing subjects to be covered on the upcoming ISA Certified Arborist Exam (contact the ISA web site for more info on the test).

On Saturday the 23rd, at the same site, A Plant Problem / Diagnosis Workshop will offer another day of classes specifically designed to earn OPM CEUs. Charge for this workshop is separate from the main conference, but the two can be combined for a savings. (again, see website for more details.)

No matter what your experience level, the Arizona Community Tree Council’s annual conference will provide you with new insights, a chance to learn from the best experts, the fun of the annual silent auction, some great networking opportunities, give-aways and prizes, and lots of CEUs. Please plan to join us in Prescott on September 22 for the annual ACTC Conference, and for the Plant Diagnosis Workshop on September 23, 2011.

Reduce the Risk of Storm Damage

Friday, 15 July, 2011

Written by Cathy Rymer, Certified Arborist

It’s monsoon season and high winds can cause serious damage to landscape trees resulting in huge economic losses.  Sometimes damage can’t be avoided but in the majority of cases tree failures are the result of mismanagement of our urban forest.

The word “monsoon” comes from the Arabic “mausim” which means “a season.” In Arizona, the process starts with the hot and dry weather of May and June.  During this time the winds are from a dry westerly direction, so humidity is low and temperatures soar above 100 degrees in the deserts. As the atmosphere warms, the jet stream retreats northward. This allows the winds to shift to a more southerly component and bring in moisture. Most of our humid air comes from the Sea of Cortez, but a good portion also comes from the Gulf of Mexico. Once the moist air arrives, our strong summer sun heats the moist air causing the familiar thunderstorm clouds.

Here are some common Monsoon Terms:

  • Haboob: walls of dust coming from the south, can get 3,000 feet high
  • Gustnadoes – combination of dust devils and tornadoes
  • Dust Devils – micro-tornadoes that reach up to 1,000 feet tall, majority are pretty small.
  • Downburst – contain strong down drafts, 2 types
    • Macrobursts – 2.5 miles or more in a diameter section and last for 5 or 20 minutes.
    • Microbursts – 2.5 miles or less in a diameter section with winds forced and bursting outward.  These cause the most damage.

Why Do Trees Fail in High Winds?

There several types of failures.

  • Root failure
  • Trunk failure
  • Branch attachment failure
  • Branch failure

There are six key reasons why trees fail.

1.     Nursery Production Techniques

2.     Tree Site Incompatibilities

3.     Pruning / Planting Practices

4.     Disease Pathogens and Insect Pests

5.     Watering

6.     Genetics

Let’s look at the reasons one at a time.

1. Nursery Production Techniques. This refers to root deformation at the nursery resulting in a girdled root system.  Roots grow and follow the boundary of the container creating a circular pattern.  After planting, the roots begin to grow around the main stem of the tree and cut off or restrict the movement of water, plant nutrients and stored food reserves.

To avoid girdling roots, select quality nursery stock and visually inspect the tree.  Buy young stock, rather than old stock.  Look for roots protruding above the soil line.  Use your finger to probe the soil near the trunk to feel for girdling roots.  At planting, score the rootball in several places to interrupt any circling pattern.  Other techniques include shaving the roots and air excavation of the roots.  A healthy rooted tree is able to distribute stress and minimize a chance of it being uprooted.

2. Tree Site Incompatibilities. Unfavorable site conditions can cause the development of stresses.  This reduces their ability to withstand pathogens and insect damage.  Some species are not suited for particular sites such as parking lot islands or street medians.  Some species do not tolerate lawn conditions or soggy soils.  Some species should never be planted under power lines where, because of their height, they are subject to line clearance practices.  Care should be taken when planting trees near structures where, if placed too closely, they can interfere with roofs or walls.  The motto of “right tree – right place” should always be used when planting a tree.

3. Pruning / Planting Practices. Pruning can actually contribute to failure.  Trees that are pruned into pre-formed shapes sets them up for failure.  For example, lifting the canopies of trees creating the ‘umbrella effect’ allows wind to lift the tree.  Excessive thinning disrupts the equilibrium of the trees canopy.  Dr. Chris Martin from Arizona State University says: “Trees are self-optimizing structures, when a force hits them on a certain side; they distribute the stress equally to minimize it so the tree is able to stand.  When we mess around with the tree and limit its ability to distribute equally around the tree that causes stress, and we see failure.”  Removing the interior branches and foliage or ‘lions tailing’ redistributes the weight to the ends of the branches making them more vulnerable to wind damage.  There are multiple reasons we see large branch breakage during monsoons.  It can be said that trees that are managed this way are selected for failure.

Planting procedures can also contribute to ‘wind throw’ or trees blowing over.  Trees placed too deeply in planting holes are subject to backfill that can suffocate the root crown.  Some arborists report that 95% of trees are too deep in the top of the container before planting. Holes dug with augers create smooth sides that roots have difficulty growing through.  Amending the back fill can be detrimental to root growth.  Staking ties that aren’t loosened periodically can strangle trunks and create weak points subject to breakage.  The practice of removing small branches on the trunk contributes to sunburn and restricts nutrients distribution for the tree.

4. Disease Pathogens and Insect Pests. The process of wounding trees in pruning causes rampant wood decay.  Dr. Chris Martin did a survey of primarily commercial trees, and found incidences of slime flux and other forms of wood decay on 61% of the trees.  The greater majority of trees in commercial settings are in some state of wood decay.  Fungal and bacterial pathogens can affect stressed trees.

There are two common wood boring insects that affect stressed trees.  The flatheaded borer attacks dying or dead wood.  An example would be wood damaged by sunburn resulting from branch removal.  The tree is stressed from pruning and produces chemical signals that attract the borer.  Roundheaded borers are less common and are found in living tissues of stressed trees.

5. Watering. Excessive watering of trees reduces wood density and mechanical stress tolerance.  An overwatered tree will have larger vessels, larger grains of wood, which makes it weaker.  Strength is derived from density or packing of vessels.  Chronically over irrigating causes wood density to decline.  This is particularly problematic with desert trees brought into the city.  Reduced wood density causes less ability to withstand stress. In an over-irrigated situation it also affects the shoot to root ratio, resulting in reduced ability for the tree to be stable.  The root system is smaller than it would normally be and in high winds the tree is not stable.  The practice of limiting water and fertilizer serves to significantly slow growth and reduce the need for pruning and thinning. Good tree water management can help keep a tree stable in winds.

The location of the irrigation lines is also critical to trees stability in the soil.  Moist or saturated soil is very unstable.  As a tree grows, the emitters should be placed at the drip line where the majority of the feeder roots are located.  This allows the soil next to the trunk to become more firm as it dries out, decreasing the possibility of wind throw.

6. Genetics. Sometimes arborists are faced with nearly impossible situations that even the best pruning can’t help.  A few tree species present growth characteristics that defy logic.  One common problem is narrow branch attachment angles that is often a point where tree branches fail.  This failure usually is from included bark.  Included bark is bark embedded or turning inward between opposing branches, a branch and a main trunk or two co-dominant branches creating a structurally weak point in the tree. It prevents strong attachments of branches, often causing a crack at the point where branches meet.

Summary

What’s the biggest problem?  There is no single answer.  A tree functions as a unit that includes the leaves, branches, trunk and root system.  What is done to one part affects all the other parts.  Anything done to the top of the tree affects the roots and vice versa. To avoid tree failure, the entire tree must be managed appropriately.

Tips for Storm Damage Prevention

  • Select tree stock from reputable nursery.
  • Select the ‘right tree for the right place’.
  • Use the Tipton Planting Method by digging a shallow and broad planting hole. Refer to the ACTC Tree Planting Guide http://www.aztrees.org/tree_planting_guide.pdf
  • Avoid layering of different soil types. (topsoil layered atop of rock or caliche.)
  • Score root-ball sides at installation.
  • Prune no more than 20% percent to open canopy, keeping top growth and foliage in proportion to root mass.
  • Avoid removing foliage during seasons when sunburn can result.
  • Design an irrigation system that encourages progressive radial distribution of roots as trees mature.  Ideally, the irrigation system should allow separate water scheduling for trees and shrubs.  Water deeply, but infrequently.  Refer to Landscape Watering by the Numbers
  • Irrigation schedules should allow soil and roots to drain and dry slightly before water is reapplied.
  • Identify co-dominate leaders early and remove the smaller of the two branches or the one supporting least overall mass.

Attention Private Tree Owners –  Do NOT attempt to prune or remove any trees that are within 10 feet of overhead power lines.  Call your local utility to set up a temporary disconnect to make the situation safe. Call a Certified Arborist or Certified Tree Worker to complete work in these situations.

Fire Season Safety

Thursday, 30 June, 2011

2011 is turning out to be the worst year for fires in Arizona history. Dense dry grass growth has creating a perfect fuel and coupled with extremely hot conditions, low humidity and relentless winds, fires have resulted in hundreds of thousands of acres burned across the entire state. As we approach the holiday weekend, it is paramount that we take precautions against any more destruction of our precious forests, homes and property. Please remember that although fireworks are available to purchase, most cities forbid their use within city limits. In addition, the Arizona State Forest Service has just issued restrictions on the use of any fireworks on the nine million acres of unincorporated State Trust Lands, Game and Fish Wildlife Areas and Arizona State Parks.

What can you do to prevent wildfires? The answer is simple – create “defensible space.” This term refers to the area around a structure where fuels and vegetation are treated, cleared or reduced to slow the spread of wildfire towards the structure. It also reduces the chance of a structure fire moving from the building to the surrounding forest. Defensible space also provides room for firefighters to do their jobs. Your house is more likely to withstand a wildfire if grasses, brush, trees and other common forest fuels are managed to reduce a fire’s intensity.

Whether caused by careless humans or Mother Nature, this year’s devastating fires are a cruel reminder of the vulnerability that our homes and property have against the power of wildfires.

For more information on creating defensible spaces please visit:

· AZ1290 Creating Wildfire-Defensible Spaces for Your Home and Property

· AZ1291 Fire-Resistant Landscaping

· AZ1288 Homeowners’ “Inside Out” Wildfire Checklist

Put a Cork in It!

Thursday, 2 June, 2011

Cork has been part of human life for most of recorded history and has been used for cork bottle stoppers, footwear and even flooring. Impermeable to liquids and gases, it was prized for its use for gaskets or valves in combustion engines or mechanical applications. Cork is a renewable resource harvested by carefully removing the deeply fissured bark from the Cork Oak tree (Quercus suber)*. The Cork Oak is a large evergreen tree that may stand 60 feet tall with a bulky trunk 4 feet thick to support a wide spread of gnarled, thick branches. It has leathery simple leaves (up to 2” long) that have toothed edges (5-7 each side) and are dark green above and gray underneath. The base of the leaf is flat or slightly heart-shaped. Acorns produced after flowering are oval shaped and ripen in the fruiting year. They are about an inch long, and are held in a scaly cap that encloses over half the acorn.

Early in World War II German submarines disrupted cork shipments from Spain and other Mediterranean countries. Compounding the situation, a fire, said to be one of the few authenticated acts of sabotage in the United States, destroyed Crown Cork and Seal company’s cork stockpile in Baltimore, Maryland.

The late Charles E. McManus was president of the Crown Cork and Seal, the largest user of cork in the nation. McManus declared it was high time that somebody broke the Mediterranean’s corner on the cork market.

With this thought in mind, McManus came to Arizona for a short winter vacation. He was pleasantly surprised to find a cork oak tree thriving on the grounds of the Arizona Biltmore Hotel. Twenty-five other cork trees were found growing in the divergent climates of Douglas, Tucson, Superior, Chandler, Tempe, and Phoenix.

McManus collected specimens of the corky bark and had them tested. Arizona cork, experts agreed, was equal or superior in quality to that imported. Immediately, McManus began a cork tree-planting campaign that would eventually cost him a half-million dollars.

Cork oak acorns were collected. Nurseries, government and commercial growers throughout the southland were asked to sprout the young cork trees. Wherever a climate seemed good, McManus distributed cork seedlings to all takers, free of charge.

In Arizona (about 1946), carloads of the cork seedlings were given away to farmers, to homeowners, to recreation areas, to resorts, to companies and utilities. One railroad car containing 6,000 young trees was emptied in two hours. All together an estimated 100,000 trees were distributed.

Parallel with the planting of cork trees in Arizona’s cultivated areas, McManus hoped to spread cork trees through the forests. Tons of acorns were gathered for this program. Experimental plots were set up in two Arizona forests, generally under the Mogollon Rim.

With McManus’s death in 1946, interest in the program began to fade. Buell Tade, who had acquired the nickname, Corky, because of his work in distributing the trees in Arizona, tried to continue the work. But without the financial leadership of McManus the planting of cork trees was soon stopped. Tade hoped that thousands of the trees would survive and wanted to have a registry for the trees whose cork could be harvested by crews.

Although all of the cork trees planted in the forests are dead due to drought, and perhaps the hard freezes of high elevations, which were too much for the seedlings, dozens survive to this day in urban areas. The Arizona Community Tree Council has designated several as Heritage Trees and recognizes them on their web site at www.aztrees.org.

*Stripping off the cork doesn’t hurt the tree. It just speeds up the production of cork bark. A cork tree is ready for its first harvest when it is about 20 years old. The first harvest is of poor quality, and can only be used for packing material or to make agglomerated cork products. A 40 year old tree is just reaching its full production. Subsequent harvests occur at nine-year intervals, when the cork layer reaches a thickness of 1-2 in. The harvest from a young tree yields about 35 lb of cork, while the yield for an older tree may be 500 lb. Each tree has a productive life of about 150 years.

Indigenous Imposter – Desert Willow

Wednesday, 13 April, 2011

by Cathy Rymer, Certified Arborist, Master Gardener, Water Conservation Coordinator, City of Chandler

BOTANICAL NAME
Chilopsis linearis

COMMON NAMES
Desert Willow, Desert Catalpa, Flowering Willow, False Willow, Jano

The long, narrow leaves of this plant are reminiscent of willows, but this imposter isn’t a willow at all.  Rather, it’s a close relative of the catalpa tree and a member of the trumpet vine family (Bignoniaceae). Desert willow is drought-tolerant and can be found naturally growing along our ephemeral streambeds or washes where it is a natural protector against flood and erosion damage.  From May through October colorful, large, slightly scented tubular flowers bloom making this attractive tree popular in our urban landscapes.

Spectacular silhouettes of Desert Willow are created when the winter sun sets low on the horizon.  While some plants become obscure and hard to identify without their familiar green foliage, the form of Chilopsis linearis is unmistakable even without its leaves.  Its branches seem to zigzag their way to the edge of the canopy.  Long, narrow, papery pods hang as decorations and release their treasured seeds to hungry birds throughout the winter season.

Classification and Range
Desert willow is a deciduous large shrub or small tree that can grow to 25 feet tall and 20 feet wide.  It primarily occupies dry washes, intermittent streams and other watercourses, and moist canyons in deserts and mountain foothills between 1,500 and 5,000 feet in elevation throughout much of the southwestern United States and into Mexico. Desert willow plants are long-lived and help stabilize the banks of watercourses.

A component of desert wash communities that are somewhat stable, desert willow sometimes establishes itself in freshly deposited channel sediments following seasonal water runoff.  As plants develop they may trap sediments, leading to the formation of islands within the channel.

Common associates of desert washes include blue palo verde (Cercidium floridum), desert ironwood (Olneya tesota), catclaw acacia (Acacia greggii), smoketree (Dalea spinosa), mesquites (Prosopis spp.), desert broom (Baccharis sarothroides), netleaf hackberry (Celtis reticulata), and littleleaf sumac (Rhus microphylla).

Description
The form of this tree is multi-trunked with a graceful appearance.  The long, narrow, curving leaves are simple, solitary, linear, and range between 5 and 12 inches long and 1/4 to 1 inch wide with a surprisingly tough, leathery texture.  Attractive white, burgundy or pink colored trumpet-shaped, orchid-like flowers with distinctive yellow throats appear in terminal clusters from May-October.  The resulting seedpods are dehiscent, 4-9in long, and cling persistently on branches throughout winter.  The bark of Chilopsis linearis is smooth when young but develops rough fissures with age.  Prominent lenticels are noticeable on new growth.  Plants are winter deciduous and drop leaves in late fall following the first hard frost but are cold hardy to 0°.

Propagation and Care
Tolerant of most soils as long as drainage is good, this tree prefers location in full sun, although it will tolerate partial shade.  Established plants are considered drought-tolerant and require the deep, infrequent irrigations recommended for most desert-adapted trees.  Little maintenance is required for this tree with the exception of minor selective pruning if a more tree-like form is desired.  Fallen leaves and seedpods blend into a coarse groundcover.  Easily propagated from seed, Desert willow can also be grown vegetatively from cuttings and is a fast grower in urban landscapes.  Individuals have been selected from the wild, cross pollinated with other specimens, cloned, and marketed with characteristics such as specific flower color or growth habit.  Some of the newer varieties are “Rio Salado”, "Lucretia Hamilton", "Warren Jones", and "Lois Adams".

Russian hybridizers from Tashkent, Uzbekistan, crossed the catalpa (Catalpa bignonoides) with the desert willow, which resulted in the Chitalpa (Chitalpa tashkentensis): This tree produces no seeds.

Landscape Uses
In hot, dry areas the attractive form, willow-like leaves and beautiful blooms of Chilopsis linearis are a welcome relief.  It is a must-have for luring hummingbirds into a landscape.  Even small native birds like verdins will be search out the nectar-producing flowers (although they tend to pierce the flower at the base as a short cut).  If placed on the south, east or west side of homes it will provide shade in the summer while allowing ambient heating in the winter.  Using nearby evergreen shrubs and groundcovers will lent contrast to this tree’s deciduous appearance in winter.  Planted in groups, it can be used as a screen or windbreak and provides shelter for nesting birds.

<[>History & Folklore
The strong yet flexible wood of Desert-Willow was used by Indians to craft their hunting bows. The wood has also been used by the Pima to thatch roofs, in house construction and in making of baskets to store mesquite beans, acorns and other foods.  The fibrous bark was used to make nets and fabrics.  Important to wildlife because it provides nesting sites and cover, animals such as deer and birds also consume the leaves, fruit and the flower’s nectar. Birds eat the white-fringed seeds and bees for honey use the pollen.

Medicinal Uses
The desert willow’s flowers, leaves, or bark can be used as a hot poultice or a soothing tea for coughing. Other treatments guard against yeast infections, athlete’s foot and a first-aid technique for scrapes and scratches.  The plant carries an additional use as an anti-fungal and anti-candida product (yeast). The tea (from the flowers) produces a natural anti-oxidant, which promotes cardiovascular health and regulates glucose metabolism.   (This section from http://medplant.nmsu.edu/chilopsis.htm).

By including one of these trees in your landscape you can have color and fragrance; attract native birds and other wildlife; and have shade and/or sun in places where it’s needed.  If you’re looking for a specific flower color, shop at local nurseries when the trees are in bloom.  Desert willow trees propagated from seed can vary in their flower production and color intensity. Named cultivars that are propagated vegetatively will be consistent in these characteristics.  Look for a tree with good vigor and a profusion of blooms in the color you like.

Help for Freeze-Damaged Landscapes

Friday, 7 January, 2011

By Cathy Rymer, City of Chandler

Even in the desert freezing temperatures can occur causing damage to many landscape plants and making them look a bit ‘toasted’.  While many frost-sensitive plants can tolerate freezing temperatures for brief periods, nights that dip into the low 30’s or below for several hours can be deadly for even the hardiest of plants.

Trees that are the most vulnerable to freezing temperatures include Ficus nitida, Jacaranda, citrus, young Sissoo, Royal Poinciana, citrus and tropical fruits.

What can you do now?  First, resist the urge to prune off any dead or damaged foliage for a few more weeks.  Even the crispy leaves and stems will act as an insulator and protect the interior of the plant against any future frosts.  You may not be able to protect a large tree completely so focus on protecting the trunk from the soil line up. If the temperature dips below 20 to 22 degrees, a heat source may be necessary. Christmas tree lights or a mechanic’s light will work.  If the tree is small, fashion a tent around the whole tree or base and heat it with. Turn the light on in the afternoon and leave it on until mid-morning the next day.

You don’t need to be overly fussy about the covering. Agricultural fabric, sheets and blankets work well and the seal does not have to be tight. This may be the one time to use plastic to make a tent, as it retains heat well. Just be aware any leaves that touch the plastic will likely burn. Of course, the survival of the plant or tree is most important. Also, use caution when using a heat source with plastic covering. A hot bulb will melt plastic.

Typically our last frost date occurs in late February, although there have been rare occasions where frosts have been recorded in March.  Waiting until then will actually make it easier to tell where tissue damaged by the freezes ends and live tissue begins.  As new leaf buds emerge the green color will indicate where it is safe to prune away the dead foliage or stems.

If you’re in doubt about pruning you may want to consult a professional.  The Arizona Community Tree Council web site has a listing of certified arborists and tree care specialists at  www.aztrees.org.

Best Time to Prune (Phoenix & Tucson metro areas)

Desert Adapted Trees Early summer (May – early June)
Desert Adapted deciduous trees During winter dormancy (January)
Conifers (pines, junipers, cypress) During winter dormancy (January)
Citrus Don’t prune except for hazards or health
Frost-sensitive trees and shrubs Remove damaged foliage after danger of frost has passed (late February into March)

To learn more about the correct pruning of desert plants try “Pruning, Planting & Care”, by Eric A. Johnson. It is filled with great information and step-by-step instructions. ISBN 0‑9638236‑5‑1.

The University of Arizona has a wealth of information on-line.  Try AZ1002 Frost Protection http://cals.arizona.edu/pubs/garden/az1002.pdf

Better yet, make plans to attend one of the free Homeowner Tree Care workshops offered by ACTC.  Check the on line calendar for a dates and locations near you. www.aztrees.org

Holiday Trees—Sustainable and Renewable

Thursday, 9 December, 2010

There’s nothing like the fragrance, the look, and the tradition of a fresh holiday tree. It’s one of the focal points of the holiday celebration and just can’t be matched by artificial substitutes. Most Christmas trees are grown at commercial farms and nurseries as a sustainable crop where it can take from five to 12 years to produce a tree. Once cut or dug and sold in containers, new trees are replanted the following spring making them both renewable and recyclable.

Finding your tree

Choose a tree lot that has trees standing in containers with water, or that have trees shaded, cooled and kept moist under tarps. Asphalt surfaces can absorb and retain tremendous amounts of heat that can quickly dry trees out.

There are a number of varieties to choose from. Fraser, Noble and Douglas firs and Scotch pine are the most popular varieties sold. Noble and Fraser firs are considered best at staying fresh and holding their needles the longest. Look for trees with green needles and full foliage; when you run your hand along a branch, those green needles should stay put. If they all fall off in your hand, keep looking. Regardless of the type you choose, purchase your tree as soon as possible, even if you intend to wait to put it up.

When you get your tree home

Once you get your tree home can keep it in the garage, on the north side of your home or other cool location out of the sun. As soon as possible make a fresh, straight cut across the base of the trunk (about one half inch up from the original cut) and place the tree in a tree stand that holds an adequate water supply.or in a pail of water until you’re ready to bring it indoors.

Select a location to display your tree and make sure it’s away from any heat sources, like heater vents or fireplaces. Trees like cold temperatures and high humidity, so keep that in mind. In the first 24 hours a tree will absorb as much as a gallon of water or more and one or more quarts per day after that. Water is important because it prevents the needles from drying and dropping off and the boughs from drooping. Keeping it well watered is the single most important step in avoiding a tree that dries out. Check on the water at least once a day as a sap seal can form across the cut end in just a few hours and will prevent any more water from being absorbed.

Keeping your tree fresh

Research has shown that plain tap water is all that’s needed. Some commercial additives and home concoctions can actually be detrimental to a tree’s moisture retention and increase needle loss. Water holding stands that are kept filled with plain water will extend the freshness of trees for weeks.

Safety tips

  1. Avoid combustible decorations such as paper, wood, or plastic.
  2. Always unplug your lights/decorations before going to bed or leaving home.
  3. Make sure your smoke detector is in good working order and a fire extinguisher is nearby and in good working order.
  4. Never place candles or other open flame sources on or near your tree.

Living Christmas trees

Living trees are a perfect choice for those that want to plant a tree after the holidays. Look for varieties that will grow in your area. For the low deserts choose Aleppo Pine, Eldarica (Afghan) Pine or Italian Stone Pine. For higher elevations look for Austrian Pine, Pinon Pine, Douglas fir or Arizona Cypress.

  • Leave the tree outside or in a cold garage until you’re ready to decorate it – keeping in mind that a living pine tree can stay inside only for about ten days.
  • Clean your tree before you bring it inside – brush off dead needles and spider webs and wipe off dust.
  • Place a protective shield under the tree’s container to prevent damage to floors or tabletops.
  • Check the soil daily for dryness – it should stay damp but not wet, and it will need more water inside than it needs outside. Ice cubes can be used to water the tree if you like. They melt slowly and can prevent overwatering.
  • Move the tree back outside as soon as possible after the holidays.

After the holidays

Once your tree is no longer absorbing water, it’s time to take it down. Don’t wait until all the needles have dried out or dropped off as it can become a fire hazard.

Instead of sending your tree to the landfill, why not recycle it? Many communities schedule tree pick-up days or provide drop off locations where trees will be chipped and used for mulch and compost.

If you don’t have room in your yard for your living tree, check with your city’s parks department. They often accept donations of live trees to be used in parks or public spaces.

For more information on holiday trees visit the National Christmas Tree Association http://www.christmastree.org/debate.cfm