Sunday, December 22, 2013

Back in the day.

I just started getting into the book 'Tree Disease Concepts' by Paul D. Manion.  The book has been out of print for some time, but Dr. Glen Stanosz mentioned it as a good resource at his talk during the recent TCI Expo here in Charlotte, NC.  By some serendipitous alignment of the stars, a retiring arborist friend of mine had given me the book just weeks beforehand.

The book begins with a historical perspective of plant diseases.  Around 300 B.C.E. the philosopher Theophrastus, known to many as the father of botany, 'recognized that wild trees were not liable to the ravages of disease, whereas cultivated plants were subject to an array of devastating diseases.'  This seems very interesting to me.  Since ancient times humans have, with the best intentions, been trying to grow plants, but missing the big picture when caring for them in the landscape.  The battles of poor cultural management we arborists fight on a daily basis, have probably been taking place for eons!  Imagine mulch volcanoes on olive trees planted around the Acropolis.

Another thought; we are members of a global economy.  Because of shipping and imports, numerous tree diseases and pests have been introduced to the US.  Around the time of Theophrastus Greece was the center of a global economy.  One may wonder how many of the diseases ravaging the urban trees of Ancient Greece were introduced from afar.

Theophrastus, the father of botany.
Pic borrowed from Wikipedia (you should donate to Wikipedia)

Sunday, December 1, 2013

Where they headin'?

Recently, a study by US Forest Service Researcher Christopher W. Woodall reported that 70% of 'northern' tree species are regenerating significantly further north and/or at higher elevations than their mean biomasses (where most of the mature trees of that species historically grow).  If the current trend stands, many northern tree species' biomass may migrate up to 62-miles (100-kilometers) over the next century.  Other species' range appear to be decreasing all together, though they may be thriving in Canada since this study only sampled trees in the United States.  While northern tree species are retreating northward, southern species are having greater seedling success at higher latitudes, and some signs show that some southern species may begin invading even more southern latitudes.

Bob Dylan said 'the times they are a-changin,' and many researchers would agree.  Now we can debate whether climate change is real, and whether its causes are natural or man made, but for the sake of argument let's agree something is happening with our climate.  Our question is 'what about our urban and landscape trees?'  The affects of climate change on tree species may be somewhat predictable.  Decline diseases on sensitive tree species may become more pronounced, thus shrinking the area suitable for them to grow.  While other, more adaptable, species may thrive in greater ranges.

We can look at this as both a challenge and an opportunity.  The challenge will come from trying to preserve some well-loved and traditionally planted landscape species.  Pest and disease ranges will likely change as well, and so our management strategies will need to adapt.  But in some instances, there will be opportunities to introduce and diversify our landscapes with new plant species/varieties.  I know I wouldn't mind having some nice flowering oleander (Nerium oleander) in my, for now, zone 7 garden.

Check out your hardiness zone.

Sunday, November 24, 2013

Remember to sweat the small stuff.

Every time we apply a product to solve a plant 'problem' we are changing the environment in some way.  The collateral damage caused by our plant heath care actions can range from minor to catastrophic; for example, the large bee kill in Oregon this past year.  Even soil-applied fertilizers will affect soil chemistry in unintended ways.  High concentrations of some plant essential elements can be antagonistic to other plant essential elements, making them unavailable for uptake.

We have a responsibility to take proper precautions, make accurate diagnoses, and know what and how things we are doing will affect the world around us.  Our management goals should be based around having as little impact as possible, and in the end, introducing as little outside product as possible in to the environment. As arborists we are expected to be stewards of the environment, and this is something we shouldn't take lightly.

Something that seems as unintrusive as applying an adhesive band to the tree can capture a range of off-target insects, reptiles, and mammals.

Sunday, November 3, 2013

The construction conundrum.

This week we have a guest writer featured on the Wandering Arborist. Brandon Hogan is an ISA Certified Arborist & Municipal Specialist, and is ISA Tree Risk Assessment Qualified. Currently he is a sales consultant at Heartwood Tree Service in Charlotte, NC, but has also had an opportunity to travel throughout most of North America creating tree inventory and management plans. Enjoy.

There are two major concerns when trying to preserve tree(s) within construction sites.  The first is preventing physical injury to the tree in the form of damage to branches, trunk or roots.  The second is soil disturbance in the form of compaction and changes to the grade or elevation of the soil.  Preventing physical injury to trees during construction can best be accomplished through installation of a physical barrier between the worksite and the tree.  This area is designated as the Tree Protection Zone and serves not only to protect the tree from physical injury, but also minimize the disturbance to the surrounding soil.  

Physical injury to a tree can lead to a wide variety of issues depending on the location and extent of damage.  Wounds created through improper pruning, careless equipment use or root severance can open the door to pest, disease, or decay issues in many trees.  Soils are where trees, live so protecting them is vital for any tree.  Soils can be easily damaged through compaction created by mechanical equipment or the storage of heavy materials (bricks, stone, etc.).  Compaction creates an environment below ground that will be less conducive to root growth and health.  The addition or removal of soil near a tree can also have a negative effect on its health.  Removing soil can damage roots and adding soil can suffocate them.  In addition, even grade changes a good distance away from the tree can change how water flows through a site and how much will be available to the tree in the future.  

Tree where absolutely no thought is given to preservation.

Ideally the Tree Protection Zone would extend outward from the trunk of the tree in a circle to the outer limits of its canopy (drip zone).  Usually coordining off this large of an area within a construction site isn't feasible.   In this case, protecting as large an area as possible within the tree’s drip zone is recommended.  Generally, the minimum acceptable distance for the Tree Protection Zone from the the tree would be a circle extending out from the trunk a distance of 3Xs the diameter of the tree, measured at 4.5 feet above ground.  Excavations leading to root severance within this zone can create structural issues that may warrant the removal of the tree.  By severing large roots very close to the trunk, not only is the tree’s ability to extract water, nutrients, etc. from the soil compromised, but also its ability to anchor itself to the ground.  

Here an effort is made in erecting tree protection.  While the trunk seems well protected, little thought is given to protect valuable soil.  Care should be taken to preserve as much undisturbed soil as possible. (PA)

Not every tree is a good candidate to try and preserve through a construction project.  There are several other steps that would need to be taken both before, during and after the construction project to ensure the tree remains healthy and stable.  The steps will vary with each tree and site.  Protecting the soil and tree itself during the construction is a practice that will apply to any site.  The larger an area that can be protected around the tree the better chance that tree will have of remaining for many years after construction is completed.  

Sunday, October 27, 2013

What big thorns you have.

Have you ever noticed the thorns on a honey locust and thought to yourself 'what's goin' on with those big daggum thorns?'  Honey locust evolved along side the Pleistocene megafauna.  Extinct animals such as woolly mammoths, mastodons, and giant sloths used to roam North America, and likely fed on the seeds of honey locusts and water locusts.  
These trees depend upon large mammals eating their seeds and passing them through their gastrointestinal tract out as a way of dispersal.  But inviting a 5-ton animal to dinner can be dangerous, thus the reason for thorns that can be 8-inches long.  The prehistoric mammal gets a meal, the tree's seeds are spread, and the thorns keep the dinner guest far enough away from the tree so it can survive to make another crop of seeds next season.

Next time you see a honey locust just imagine, one of it's ancestors probably grew because a woolly mammoth pooped it out somewhere.

Honey locust thorns, they'll take your eye out.

Sunday, October 20, 2013

The Band, a spray alternative.

When controlling pests on trees and shrubs we often think of spraying some kind of chemical product, and while this is often our only course of action, for some pests there are alternatives.  Many pests can be physically removed.  Webworms and tent caterpillar nests can be pruned out or destroyed.  White peach/prunicolia scale can be scrubbed off the stems of small cherry laurels and lilacs.
Another non-chemical method for preventing pest injury to trees is creating a physical barrier.  This is most effective against certain species of lepidoptera that climb from the ground in to the canopies of trees to feed or lay eggs.  In the Charlotte, NC metro area there's an unprecedentedly large population of fall cankerworms (Alsophila pometaria).  There are many theories as to why cankerworm numbers are so large, but no doubt part of the problem lies within the overwhelming number of mature willow oaks (Quecus phellos) lining streets and gracing private yards.  
Cankerworm adults emerge from the ground after the 1st series of cold nights (at or below freezing) in the late fall/early winter.  The adult female cankerworm doesn't have wings, and is forced to climb up the trunk into the canopy of a tree to mate and lay eggs.  Each female can lay  between 100-200 eggs.  In spring, just as leaves are approaching full expansion, the little inching cankerworms emerge from their eggs and feed on the tender young foliage.
These cankerworms are present in such damaging numbers that the city of Charlotte, and most of her residents, habitually affix bands covered or lined with sticky stuff to trees throughout the fall.  This way cankerworms are controlled safely and economically.

Heartwood Tree Service Arborist affixing 'Bug Barrier' to the trunk of a willow oak.

Sunday, October 6, 2013

Is it over reacting?

Trees respond to damage or decay by forming reaction wood.  The placement and extent of reaction wood can be telling of where and how long the tree has been affected by decay.  When we think about a tree responding to decay organisms,  most often our first thought is the compartmentalization of decay in trees (CODIT) model.  However, the CODIT model is based upon a tree's reaction to damage to the bark and cambium.  When decay enters from the tree's structural root system, or perhaps an old tap root that has died off, trees react a little differently since the decay organism is growing in duramen (heartwood) tissue, which is effectively dead structural tissue.

The root flare of the willow oak pictured below has been quite disfigured by years of attempting to out grow Inonotus dryadeus and Ganoderma lucidum.  When sampled with an IML-Resistograph, what appears to be a substantial amount of wood reveals areas and pockets of substantial decay.

Sunday, September 15, 2013

That's going to be trouble...

When assessing a tree's risk of failure we must sometimes look for the finer signs and symptoms that may indicate a tree's potential to fail.  The convenience of giant decay conks, broken roots, and huge decayed cavities may not always be evident on a tree that presents a high risk of failure.

Let's look at some pictures of a tree that from a distance may seem fine, but upon closer inspection proved to be cause for alarm.

Notice the soil heaving on the tension side of the lean.

Saw dust or frass present on several areas around on the lower trunk.  When sounded with a hammer decay was detected.

Small armillaria fruiting bodies protruding from the root flare of the tree on the tension side of the lean.  Armillaria root rot is a serious structural root decaying fungus which results in a white rot.

From a distance this willow oak has a perfectly green and balanced canopy, and is in a beautifully maintained yard.  Upon closer inspection the tree described above displays some serious evidence of strength loss.  Further proof that when walking a property, we can take nothing for granted.

Sunday, August 25, 2013

I'm fallin'

When discussing tree risk assessments we talk about looking for signs a tree is likely to fail.  The following pictures are of a white oak that some may argue is in the process of failure.  Let's take a look....

As we approach the tree, notice first the lean. What this picture doesn't show is the residence within 50ft of the tree's base.

Soil heaving, especially on the side of the tree opposite the lean, is pronounced.

Here we can see where large roots are separating from the soil.

Another image of large roots separating from the soil, and some resulting voids in the soil.
After discussing these issues with the client I discovered that 5 years ago this white oak was on the edge of a wooded area that had been cleared to make room for a new home lot.  This tree had spent most of its existence to this point with mature neighboring trees protecting it from wind and storm events on the side opposite of where it is now leaning.

By altering this tree's environment, a tree that may have lasted for years to come was turned in to a tree that is now at an extremely high risk for failure.

Sunday, August 11, 2013

Don't be STUBborn

For decades we've known when pruning the final cut should be at, or just outside, the branch collar.  When trees shed branches naturally it's at this point. This is where the tree has the easiest time compartmentalizing and growing over the wound.
Now, it seems there's been some debate over the past few years about what to do when pruning larger branches back to parent stems on mature trees.  Some seasoned arborists have insisted that leaving a stub is prudent when dealing with large branches.  The idea is that by leaving a stub, decay will be slowed when moving into the stem.  
What needs to be considered though, is in a short period of time the vascular system around this stub is going to die.  This means any physiological process the tree has to fend off decay will cease, creating a corridor for decay to enter the parent stem through both heartwood rots and sapwood rots.
Below is a picture of a willow oak damaged in a storm 3 or 4 years ago.  During the storm a large branch broke out leaving a substantial stub.  In that time I've driven past this tree almost every day.  A few weeks ago I noticed bark separating from the underside of the damaged limb.  When I got out to look, it was obvious that sapwood decay had moved from the dead stub into the parent branch.  Had a proper cut been made the tree would have had a better chance of reacting to the damage.  Sure, decay still may have moved in to the stem, but the tree would have been putting on reaction wood to close the wound and reinforce the structural wood around the damage.

The red arrow shows where decay has moved from the damaged stub into the parent branch.  You can also see wound wood forming around the decay.  This has become a large area to heal over vs. if a proper cut was made at the branch collar.

Sunday, August 4, 2013

It's Phytoplasmatic

Phytoplasma are specialized bacteria-like organisms that are obligate parasites of phloem tissue, and they can do strange things to plants.  Phytoplasma can cause leaf yellowing/variegation, twig distortion, witches brooms, etc.  They are spread by insects, like leaf hoppers, from infected plants to new hosts. 

In most instances infection by phytoplasma is not big deal, but in the case of a few diseases, namely; elm yellows, ash yellows, lilac witch’s broom, and grapevine yellows it can be deadly.  The best control method of phytoplasma is the removal, and offsite disposal of affected plant material.  Insecticide treatments to control the vectors may be helpful as well.

Diagnoses of phytoplasma can be difficult.  Viruses, bacteria, and fungal infections can mimic phytoplasma symptoms.  The picture below is a willow oak branch displaying some weird symptoms.  What’s causing it?  Phytoplasma?  Sure.

'Crispy black stuff'

Wood decay fungi come in many shapes and sizes.  Their fruiting bodies are generally pretty easy to identify.  Mushrooms and conks along the base of a tree or attached to the trunk can be eye catching.  One commonly over looked and miss identified structural root/basal decay fungi is Brittle Cinder Fungus (Kretzchmaria deusta  formerly Ustulina deusta).  Brittle Cinder causes a soft rot that breaks down cellulose and hemi-cellulose followed by lignin.  This creates a decay that leaves wood feeling brittle.  Early stages of this decay can be hard to detect with a traditional 1/8th-inch bit and drill.

Perhaps the hardest part of identifying this decay fungi is simply noticing it.  Brittle Cinder fruiting bodies first appear as grey-white masses growing only slightly raised from the bark of the tree.  At first sight, they may be mistaken for dead lichens.  As the fruiting bodies mature, they become black and appear as burned bark.  Deusta means 'burned up.'  Unlike most common wood decay fungi, Brittle Cinder is an Ascomycota versus a Basidiomycota.

Brittle Cinder affects a vast array of tree species,including; beech, oak, maple, and linden.  Infection usually occurs through wounds in the bark.  Brittle Cinder can result in significant strength loss, so careful consideration should be taken if this fungus is located on a tree.

Here, Brittle Cinder is growing on the root flare of a red maple.  There is only 1.5-inches to 0-inches of sound wood around the affected area.

Sunday, July 14, 2013

Well that's something

While looking at some storm damage a few weeks ago I happened upon this pear.  Like many pears it was cursed with multiple co-dominate stems that tore from the tree during high winds and rain.  While there is nothing special about a flowering pear breaking in a storm event, what's cool about this tree is what was exposed after the tree failed.  The limbs that failed pealed down the trunk to expose branches pruned in the past.

This pear offered a rare glimpse of how trees create new wood around the stem and branches, from the inside.  If only we could dissect some more pears for the greater good, enjoy the pictures below.

You can clearly see the remnants of past pruning.

Another view of past pruning wounds exposed when a portion of this tree failed.

Sunday, June 30, 2013

What's your design intent?

Our landscapes, no matter how manicured or wild, are artificial.  By artificial I mean, they are heavily influenced by we humans, not unlike the interior of your home.  Some of us have rooms which are color matched perfect to patterns and furniture that's strategically placed, while others may have rooms that are more eclectic.  Like our interiors, our landscapes are subject to change based upon our discretion.  Few people will have their first living room couch, still, in their living room after-long.  It's accepted that tastes and styles will change with interior design, and it's ok for the same to happen with the plant life in your yard.  Just like you would throw out an end-table bought at the discount store when it became scratched, some plants are worth culling if you're not attached to them, or if they become a maintenance concern.  Conversely, you may take great pains to restore an heirloom grandfather clock, and so you may with a centuries old oak tree.

As your couch becomes older it probably won't be getting larger and encroaching upon other parts of your home, as your trees and shrubs may.  Mature plant size, placement, and the intent of design (as landscape architects put it) are paramount when choosing trees and shrubs for the landscape.  We all want immediate results, but immediate results in the landscape can mean high maintenance costs or whole tree/shrub removal in the future.  The latter are fine, as long as you understand them from the start.

While redoing a room in your home can be completed fairly easily, sometimes achieving that intent of design in the landscape can be a process.  When landscapes are young, they usually look good.  The plants are all small, healthy, and well spaced. Then, just like all little children, your landscape hits adolescence, and suddenly things don't look as cute and pretty.  Not everything is growing at the same pace, some plants are dead, or dying, and things are generally awkward.  This is where having a design intent is important, and where keeping to it can be difficult.  Many people will want to take action, and maybe some action is needed.  This may include replacing a few plants, doing some fertilizing, or pruning, but should not be drastic as replacing whole swaths of landscape.  Keep in mind, many of your favorite gardens and arboreta (Longwood Gardens, Kew Royal Botanical Gardens, The Morton Arboretum, The Arnold Arboretum, etc)  began with young and immature plants.

Change in the landscape is good, and something I encourage my clients to do.  Why nurse along an old decrepit azalea, when it can be replaced by one of the new Encore varieties.  That being said, staying the course is often the best way to go, because one day that spindly     name your favorite tree   is going to be magnificent.

These trees were 3-inch caliper when planted a few years after WWI.  They are now close to 40-inches DBH

Sunday, June 23, 2013

Stressed out?

Explaining how trees react to stress can be difficult.  Trees may take years to react, or show signs, of past damage.  Symptoms of construction activities can take up to 8 years to reveal themselves.  This fact can leave many people skeptical of we arborists.  How can a seemingly healthy tree suddenly, and for no perceived good reason, start falling into decline?

The following small scale example attempts to illustrate how tree stress takes time to manifest.  A willow oak sapling was cut in the 2nd week of June in Charlotte, NC. Let's see what happens:

0.5 hours after being cut on a warm summer day in the afternoon.  The tree still looks green and healthy.
About 25 hours after being cut, still green with little signs of stress.

51 hours after being cut, the tree is beginning to wilt and the leaf edges are beginning to brown.

75 hours after being cut the tree is almost completely necrotic, though the twigs are still pliable. 
Larger trees, with less extreme but compound stresses, take time to show symptoms of damage.  The tree in the above example was dead on day 1, but it took 3 days to show it.  When diagnosing tree problems, a detailed knowledge of site history can be crucial when developing a tree care plan.

Sunday, June 9, 2013

Who blew it!

Golf course managers are good at managing grass, not trees.  Somehow I ended up playing golf in Miffiin, PA a few weeks ago.  Now, I'm not much of a golfer, but any excuse to be outside in one of the picturesque Central Pennsylvania valleys is a good one.  By about the 3rd hole I started noticing most of the spruces where leaning in the leeward direction.  They had been in this position for awhile, as self corrected leans were evident.

When trees are subjected to a constant force they begin developing reaction wood.  In the case of these neglected golf course spruces, structural roots on the windward side (tension side) of the trees were predominate.  These trees were left to topple over, but refused to give in.

When assessing a tree's risk for failure we must take an in-depth look at the tree.  From a peripheral view, most of the spruce trees on this course looked like they were ready to fail at any moment.  However, on closer inspection, self-corrected leans and adequate reaction wood were evident.

This spruce has quite a lean, but look at the crown architecture.  If the stem was not in the picture the tree would look perfectly up right.

Reaction wood in the structural roots, compensating for the lean.

Another view of 'beefy' roots holding the tree up.

Sunday, June 2, 2013

Wooly in the spring time.

In the spring of 2004, one of my many duties was driving around south-eastern Pennsylvania spraying hemlocks for woolly adelgid. As PA passed through my rear view mirror in winter of 2007, I was relieved in the thought I'd never have to spray a tree or shrub again.

Fast forward to the spring of 2011. I'm in my first season as PHC Manager of Heartwood Tree Service in Charlotte North Carolina, and once again I find myself treating hemlocks for woolly adelgid.  Generally speaking, the greater Charlotte area isn't the best habitat for eastern hemlock.  Poorly-drained clay soils combined with the intense Southern summer heat is in contrast to the well-drained organic soil and cooler weather hemlocks are found inhabiting in the wild. 

This specific site was just outside the city limits, on the Eastern side of what barely passes for a mountain.  It was a prefect micro-climate, with blooming mountain laurels lending feel of being in the Appalachians.  As I ascended the hill past the gated entrance, a small grove of semi-mature hemlocks appeared before me.  The trees bore the all too familiar white fluffy signs of woolly adelgid nestled at the base of the needles.

There are many options for control of woolly adelgid.  Because of the number of trees and amount of area that needed to be treated, horticultural oil seemed the best option.  Horticultural oil is gentler on beneficial arthropods, and breaks down fast in the environment.  Soil or trunk applied systemics would've been time consuming and costly to apply.  The brand of hort oil used was also OMRI certified.

Two seasons of treatment, and almost 100% control had been reached.  Sometimes the simplest, and cheapest, treatment is the best course of action.  Though something to consider, pest pressure is low on this site

Treated hemlock with no adelgid.

Untreated with adult insects and nymphs creating woolly covering.

Sunday, May 19, 2013

Protect the Zone

There are many standards for tree protection zones.  Some simply state extend a zone of protection to the dripline.  While others are more specific, stating 1ft to 1.5ft for each inch of DBH away from the trunk.  These standards are guidelines.  Tree species, size, age, perceived condition, and vigor all play a role in setting up a final tree protection zone.  Younger trees (species dependent) can probably stand a little less protected soil space compared to a mature tree.

We also need to get away from the thought of a 'tree protection zone,' and start considering a soil protection zone.  After all, its the soil the tree lives in post-construction that will determine overall health in most situations.  If we can't get the desired radius from the trunk on one side of the tree, then consider extending the radius of protection zone further on another side of the tree.  Don't think in minimums, think in maximums.  What is the maximum amount of soil I can protect around this tree?  Numerous studies show that soil volume has a direct effect on tree health and size.

Below are some pictures from a tree and soil protection zone we installed a few weeks ago.  In this case, an addition was being added to an existing home.  We were limited by what area to protect by where the addition was extending, the road, and a driveway.  In this case root pruning was in order to make clean cuts vs. the ripping that would occur when an excavator found the root.

The site and tree (Carya illinoinensis)

A trench was dug using an Airknife to expose roots that may interfere with construction. 
Example of a clean cut root.

The final tree protection fencing. We plan on creating signs to hang on all sides of the protection zone explaining what it is and why it's there.

Sunday, May 12, 2013

I smell something ferty.

Something often forgotten is that our NPK fertilizers and recommendations are based mainly on agriculture.  Most often farmers plant multiple acres of the same crop.  The crop grows from seed to maturity in these fields, absorbing all the elements essential for plant growth from the soils.  When the crop is ready for harvest the entire plant is removed from the site leaving bare soil.  Even when fields are rotated this process happens often enough to burden the soil.  In these situations, complete fertilizers with high NPKs are necessary to replace elements robbed from the soil when plants are taken from the site.

Landscape trees and soils are managed in completely different ways.  While top soils are usually stripped and vegetation removed during the construction process, it's usually a one time event.  Most soils are still able to retain many of the elements essential for plant growth.  Trees, shrubs, and other plants also produce exudates.  Though still not fully understood, exudates promote soil micro-organisms which produce available soil nutrients over time. 

Many studies comparing fertilizers and methods of fertilization often show trees respond best to simple correct mulch applications.  Trees have evolved in forests where leaves, branches and trunks are left to decay.  Correct mulch applications mimic this dynamic.

If you suspect nutrient deficiency in a tree you're managing, it's important to identify which nutrients are lacking.  Misapplication of the wrong fertilizer can be a waste of time and money, and may hurt the tree further if one element is raised to damaging levels.

Typical Soil Analysis 

Sunday, May 5, 2013

Tree myths, that's what's up.

This past week I saw an article from The Guardian about tree myths posted by The Garden Professors BLOG  I know what you're thinking, some one else spends spare time writing about plants.  But for-real, it was pretty interesting, and I'd encourage you to give it a read.  Below are my comments on the 9 myths they choose.

MYTH 1 Compost tea suppresses disease:
Compost tea can be a polarizing topic for arborists.  Compost teas are a way to introduce organic matter into the soil.  Over time this can improve soil nutrient availability, texture, and structure.  Compost tea pushers have made many claims, including that foliar application of compost teas can prevent leaf diseases.  That's just silly.  Wetting leaves with seeped organic matter may actually encourage the development of leaf diseases.  Most leaf spot fungus require a cool wet environment to proliferate, and spraying leaves with compost teas may provide the moisture.

MYTH 2 Lighten clay by adding sand:
I've seen arborists attempt to drill holes in clay soils and back fill the holes with sand, or a large aggregate like stalite.   The problem with this strategy is it ignores a basic principle of water.  Water does not move in between different textures well (i.e. course texture aggregate to a fine texture clay).  So when this management strategy is employed there is still poorly drained clay with sand filled holes full of water.

MYTH 3 Young trees should be staked:
Trees need to move naturally in the wind to put on reaction wood and build taper.

 MYTH 4 Sun through water burns leaves:
 This seems commonly reported on Japanese maples. In most cases it's actually fungal leaf spot, which really is just an aesthetic issue.

 MYTH 5 Tree wounds need dressing:
Most decay fungi need moisture to survive. Painting an open wound can allow moisture to build up behind the sealant, thus creating a perfect habitat for fungi. Now there have been some studies that show some wound sealants may discourage some insect pests from invading new tree wounds.

 MYTH 6 Biodynamic is best:
Using astrology to pick days to plant?  I suppose it would make sense to some early 20th century gardeners. 

MYTH 7 Gravel helps containers drain better:
Once again, water does not like to move between different textures. Putting gravel at the bottom of a pot has the exact opposite effect, keeping water in the finer texture soil longer.

 MYTH 8 Add bone meal and compost when planting trees:
Digging a tree, transporting it to a new area, and then planting it in a foreign soil is a big stress to a plant.  Throwing it in to a super nutrient rich media, believe it or not, can traumatize a new transplant.  Caution needs to be taken when choosing what type of amendments are being put in to the soil.  As the article states, adding to much of an element, like phosphorus, can inhibit plant growth.  More may often not be better, especially in the landscape.

MYTH 9 Natural is safer:
There is no such thing as a safe poison.  Be it found in nature or man made, poison is poison.  We use pesticides to kill pests and diseases.  Some are less toxic than others, and some have different modes of action.  When choosing a pesticide the mode of action, its persistence in the environment, etc. should be your deciding factors.  Not that it has an OMRI stamp and is made from dandelions.

Sunday, April 21, 2013

'Tis the season

The approach of spring means the beginning of 'spray season' for many tree companies.  Any time we introduce a product into the environment, pesticide or fertilizer, we are altering the ecosystem.  It's important to consider some things when choosing pesticides.  How the active ingredient controls the pest and it's residual in the landscape are important concepts in an integrated pest management program.  Care should be taken to choose products that do the least amount of harm to beneficial/benign arthropods.

Pyrethrin and spinoside are two chemicals that control many of the same insect pests.  Both mimic substances found in nature.  The difference? Pyrethrin is an indiscriminate killer of most insects and arachnids, including beneficial insects like lady bugs and mantises.  Meanwhile, spinoside has a low toxicity to many beneficial insects plants rely on for protection from herbivorous pests.  Part of integrated pest management practices are preserving, or restoring, the natural balance between pest & prey in the landscape.

Lady bug feeding on a canker work.

Another thing to keep in mind; organic is not a synonym for safe!  There are Organic Materials Review Institute-approved pyrethins that will kill most all arthropods that are exposed to the product.  Meanwhile, there are completely man-made synthetic products that will effectively control the target pest, while preserving beneficial insects.  When developing a pest management strategy, it is imperative to research active ingredients, modes of action, and persistence in the environment.  Read the labels.  Ask questions of the product developers and your local extension.  Those people are great resources, and are there to help.

Sunday, April 14, 2013

Climb on Climber

This weekend (April 13th-14th 2013) was the annual Charlotte Arborists Association Tree Climbing Competition.  It is one of the few open invitational tree climbing comps out there.  Climbers and volunteers from all over the world meet in the quaint "New South" City of Charlotte, NC for 2 days of peer learning, camaraderie, climbing, and fun.

Tree climbing competitions are a great place to learn new techniques, meet new people, and make great friends.  I've volunteered at TCCs from Pennsylvania to Louisiana, but there is one thing about comps that has always bothered me.  We can really torture some trees during these events.  Starting with set up day, the interior of the work climb tree and a portion of the aerial rescue tree is often over thinned and lions tailed.  Then on the day of the event, competitors run through the preliminaries as speedily as possible, jerking branches, smashing bark, and pulling on limbs with full force and weight.  It's like creating an artificial storm the trees must endure, with over pruning resembling the resulting loss in photosynthetic area.  We also invite spectators to mass around these trees, thus leading to potential soil compaction around, most often, mature trees.

Water oak once used as a work climb tree.  Notice numerous small pruning wounds throughout the interior of the crown.

A friend of mine once wondered if any data had been collected comparing tree health/vigor as pre and then post work climb tree.  His feeling, based upon past competition trees in Charlotte, is over all heath of the tree may decline after the event for reasons stated above.  Now this could be coincidental, or it may be that competition trees in Charlotte are used in consecutive years for different events.  If the health of these trees are being affected by repeated use, this may be a lesson to other competition organizers. It may be best practice to be one and done with trees chosen for competition.  Trees create reaction wood and adapt to their environment over time.  The sudden assault of a tree climbing competition could potentially be quite a stress for a tree.

I love tree climbing competitions, and by no means I am I suggesting they be abolished.  We are arborists, and our job is to care for trees.  This basic principle of our job shouldn't be forgotten for the sake of competition.  This year in Charlotte our head judge was Chip Hildreth, and he is a firm believer in this idea.  Chip asked the trees be thinned as little as possible for work climb and aerial rescue.  While, I don't remember his exact quote, his sentiment in the competitors meeting was similar. We are arborists, and our job is to care for trees.  Damaging the tree during the competition would result in harsh judgment and points deduction.

Our techniques and tools, along with our understanding of tree physiology are improving on a daily basis.  Our approach to tree climbing competitions, both their set up and execution, with regard to tree preservation will also improve.  One of Chip's ideas is to change the way some events (i.e. work climb) is scored.  By taking the time component out of an event like work climb, and concentrating solely on scoring by technique and finesse, we may be able to save some wear and tear on the tree. 

2013 Charlotte TCC work climb tree.  Notice preserved small diameter interior growth.  This picture was taken after the event was competed.
But enough of my ramblings, here are the final results from the 2013 Charlotte Arborists Association Annual Tree Climbing Competition (Do not hold me to the spelling competitors names):

3rd Jordan Lopshire
2nd Celestino Flores
1st Adam Hawthorn

5th Noel Boyer
4th Chris Bramlage
3rd Derek Martin
2nd Kevin Bingham
1st Cormac Nagan

2nd Sage Way
1st Marilou Dussault

Sunday, April 7, 2013

I'm fixin' to fix some nitrogen.

We know that plants in the legume family (i.e. black locust & soybeans) covert atmospheric nitrogen into a form that is available for root absorption in the soil. However it's not the plant fixing nitrogen, but bacteria known as rhizobia that form a symbiotic host relationship with the plant doing the work.

The nitrogen cycle borrowed from:

Similar in away to mycorrizal fungi, the plant provides sugars to the bacteria, and in return gains benefits from increased uptake of nitrogen. This relationship is only formed on sites that are deficient in available nitrogen. Root hairs are prompted to grow around the bacteria forming characteristic nodules.

But wait, there's more. Less thought about Frankia, a species of actinobacteria, form the same symbiotic relationship with 24 genera of actinorhizal plants.  Trees in this group are varied, and include Alnus (sample species: red alder), Myrica (sample species: wax myrtle), and the often loathed Eleagnus (sample species: autumn olive).  This plant bacteria relationship is a major source of nitrogen fixation world wide, and many if these species are commonly found in our landscapes.

Root Nodules

To see a list of actinorhizal plants check out this site: .  If you find these guys, do some digging around, and see if you can find the unmistakable nodules.  Because the list of actinorhizal plants is quite varied, and includes several species of ornamentals, incorporating these plants in to our landscape plans can be a natural and sustainable why to get available nitrogen into our soils.

Sunday, March 31, 2013

Getting to the pH of the problem

When we fertilize, our goal is to make nutrients available in the soil.  Plants may then absorb and use these nutrients in biological processes.  By taking soil samples we may determine what nutrients may be lacking, or what nutrients may be in such abundance they are creating an antagonistic environment for the plant.  Most soil samples will also return pH.

Soil pH is a measure of the acidity or basicity in soils. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions (H+ or, more precisely, H3O+ aq) in a solution. It ranges from 0 to 14, with 7 being neutral (I copied all of that from Wikipedia).

Soil pH is important. Nutrients can be made unavailable in soil at different pH ranges. Classic examples are iron (Fe) will get tied up in soils at higher pH, while phosphorous (P) will get tied up at lower pH. The pH scale is logarithmic, so there can be a big difference in availability between 5.5 & 6.

Chart of soil pH and Nutrient Availability

When managing trees in a man-made landscape, pH ranges can vary within a few feet of each other. Removal of soil layers, exposure of soil layers, and type of building material can all effect a 'micro pH environment.' Most trees enjoy a pH of around 6 (give or take). Again, depending upon multiple factors, adjusting pH to an ideal range for trees may be difficult. In addition, depending on which way you are trying to tip the scale, and which product you are using, results may take months and may be fleeting.

Take soil samples and pay attention to pH.  All of the nutrients required for growth may already be in the soil and just tied up.  Knowing this information will help arborists choose the correct soil amendments and reduce the chances of creating an antagonistic environment from over applying fertilizers.

Sunday, March 24, 2013

Conservation Arboriculture: It's About to get Weird

Conservation arboriculture sees trees as more than just landscape fixtures, but as whole ecosystems, and argues for the intrinsic value of the macro and microscopic organisms living within mature and veteran trees.   Last week a buddy of mine forwarded me a whitesheet by Neville Fay on retrenchment pruning.  This form of management is a concept practiced in conservation arboriculture.

When trees are damaged in nature it`s usually due to some catastrophic event (i.e. severe wind storm). Branches damaged in this way have wood fibers break and tear, while bark is pulled away from limbs and jagged stubs are left behind. In the aftermath all manner of fungi and arthropods make a home in the tattered remains.  Fungi feed on the newly exposed wood, insects eat the fungi, birds eat the insects, and so on.

In landscapes, trees eventually mature to where their risk of failure reaches a threshold that some mitigating action must take place.  For conservation arborists, this is where retrenchment pruning comes in.  By using coronet cuts to mimic naturally damaged limbs after reduction pruning, conservation arborists invite the natural order of things to take place.  Another technique, natural fracture pruning, is simply tying rope to branches and applying force until the branch breaks. This seems to be most popular in the UK, but I've seen coronet cuts used at The Capilano Suspension Bridge in North Vancouver, British Columbia.

Coronet cut in action. Pic from David Humphries
Final coronet. Pic from David Humphries
Obviously this isn't for everyone, or every tree.  In fact, retrenchment pruning seems to go against all traditional pruning techniques and goals.  This concept isn't meant for the feature tree in the average front yard.  But, this may be appropriate for that mature tree in the wood-line at the back of a property which poses a hazard to the swing set.  This idea may also work for any veteran tree that has fallen into the spiral of decline.  In the Capilano Suspension Bridge example, entrenchment pruning was used on declining trees along forested walkways before they became hazards.

Another thing to keep in mind, retrenchment pruning in its idealistic form can take decades of management.  Vigorous sprout growth can result from damaged limbs, and so with this form of tree management. Talk about commitment from both arborists and tree owners.  The long-term goals of all invested parties need to be discussed before this type of work is performed.

To learn more about entrenchment pruning and conservation arboriculture check out Tree Works Environmental's website:

Sunday, March 17, 2013

Not to Kick You when You're Down, but another Incredible Tree Failure

I always hate seeing a tree fall, but sometimes there is no better way to learn about the way trees grow than from a post failure forensic investigation.  And while I know our last post was about a fantastic large tree failure, this was too good to pass up.

Our subject is a large mature willow oak that suffered a tremendous root plate failure.  This tree was growing in a known flood plain, and was one of the tallest trees on the block.

Notice the amount of standing water in hole left behind when the roots pulled from the soil.  Keeping the size of the root plate in mind, and the proximity to the camellia in the picture below, notice how the wet conditions allowed the roots to be pulled from underneath soil like a magician pulling the table cloth from a fully set table.

The only indication of decay at time of failure was a cavity along the lower trunk/root flare of the tree.

Now, here is a part of the tree we don't get to see often.  With the root flare up ended we can see the structure and arrangement of the structural root system, and associated decay.

The decay column moving upward in to the stem is a common occurrence in many tree species.  It is a result of the original tap root dying off and allowing a path for decay to move into the stem.  This is a process that can take years, if not decades.  In species that compartmentalize well it is just a peripheral event, but for poor compartmentalizers, it may the defining defect in their demise.

Good thing the Jeep was insured.

Sunday, March 10, 2013

Anatomy of a Tree Failure

All trees will eventually fail.  By observing tree structure, site conditions, work history, signs of decay, etc. we may glean some insight as to how likely failure will occur in a given time period.  Let's use the following example as a case study for likelihood of tree failure.

The specimen is a mature willow oak with a 30%-40% lean towards the North East.  Prevailing winds usually blow in from the South West.  The site is several yards from a creek that is known to flood, and the area received several inches of rain over the past few weeks.  Primary power lines are close to the tree. Utility pruning has been performed on the subject for decades, leaving an uneven crown with weight distributed on the leaning portion of the stem.

Upon closer examination Inonotus dryadeus conks are present on the tension side of the lean on the root flare.  Inonotus causes a white rot in the lower stem and structural roots of trees, and is common on willow oaks in this geographic area.  Resistance drilling tells us that up to 50% of the root flare is compromised by some form of decay/damage.

Finally, a live structural root, also located on the tension side of the lean, is cracked all the way through.

The culmination of these defects resulted in whole tree failure with property damage (thankfully, no one was injured).  The tree failed in the direction of the lean.

Notice the extensive root decay.

Here we can see partial root place failure due to wet soils.

This tree is an almost text book example of a high risk of failure tree, with final results as such.  As defects compound so does likelihood of failure.  That being said, I have participated in workshops where the same high risk of failure tree has been used for years, and still stands to this day.  Assigning risk and predicting failure is one of the hardest things we do as arborists.  Documentation and communication is key.