Plant growth regulator.  That may sound scary to some, and counterintuitive to others.  Why would we want to intentionally stop a tree or shrub from growing, and how does that even work?  Believe it or not, there are many reasons why it may be beneficial to slow the growth of a plant, which include economic factors, environmental factors, and overall plant health factors.

Before we delve in to the specifics of plant growth regulators, or as I like to call them ‘plant growth managers (PGMs),’ it’s important to know that many of us come in contact with this technology quite often.  PGMs first became popular in the floriculture industry to get uniform plants that would be merchantable when they made it to the garden centers.  Have you ever noticed your house plants start becoming leggy and a bit yellow after they’ve been in the house for a few weeks?  That is because the growth regulator applied before you bought them is wearing off.

Early versions of PGMs, Type I growth regulators, were closely related to herbicides, and actually blocked cell division to accomplish reduced stem elongation.  While Type I growth regulators work very well at reducing growth there can be some unintended consequences of using them.  Namely, Type I growth regulators may cause leaf yellowing and distortion.  If applied above certain temperatures Type I growth regulators may also cause slight defoliation. 

Modern PGMs, Type II growth regulators, work within the plant to regulate the hormone (gibberellin) which is responsible for cell elongation.  This means the plant is still producing the same amount of cells, leaves, buds, etc. just those stems are extending 30%-70% less than normal.  This reduction in growth can lengthen time between pruning cycles for trees and shrubs growing in close proximity to infrastructure.  For example, the oak tree planted 10-feet from the corner of your executive building, the line of trees planted underneath those utility lines, or that hedge that needs to be trimmed a few times a year so you can see out of the first floor windows.  

Less pruning means less wounding for the plant (bonus for the plant), less time your crews need to spend managing your shrub and tree resources (bonus for labor), and also means less ‘green-waste’ your crews need to dispose of (bonus for the environment). In 2016, Rainbow Scientific, in cooperation with our partners, performed a series of trials to determine labor savings when incorporating Trimtect into their pruning operations.  Trimtect is a foliar spray-applied Type II plant growth regulator.  The sites selected contained highly manicured shrub hedges ranging in length from 50-180 feet long and 4-8 feet tall.  Over a twelve week period we found pruning time was reduced by an average of 62% when compared to shrub hedges not treated with Trimtect.  In another trial we found green waste removed from the site was reduced by 50% over a 12 week period.  Managers and crew leaders involved in the trials were unanimous in their positive response to the reduced need to prune.  Landscape crews were able to focus on getting more detail work accomplished (e.g. weeding, flower bed maintenance, trash removal, etc.), in addition to getting caught up on turf mowing and edging.  They also had less ‘call backs’ and complaints in areas where Trimtect was applied.

While plant growth managers reduce the amount of above ground growth by 30%-70%, they are also promoting responses in the plant that can encourage plant health. One positive side effect of growth control is the stimulation of another plant hormone, abscisic acid (ABA). ABA helps with preventing cell dehydration, and regulating leaf water loss by allowing stomata in the leaves to respond faster to drought conditions.  When PGMs are applied as a soil drench we see energy resources being diverted to the promotion of fine root growth. This allows a tree to mine more resources from the soil, and increases drought tolerance.  PGMs can also increase the amount of chlorophyll the plants produce.  Chlorophyll is, of course, what gives a leaf its green color, and plays a major role in photosynthesis.  Disease resistance to certain fungal leaf and canker diseases has also been recorded with the application of PGMs.  So, not only can you employ PGMs as a growth management tool, but they can also be employed as a plant health care tool.

The use of plant growth managers can often be overlooked, but when used correctly, can be a substantial tool to help reduce time spent on pruning while also benefiting plant health.  Next time you’re walking through your site think of those hedges, ground covers, trees, and vines that seem to need constant attention.  Now imagine, instead of the plants dictating your pruning schedule, you dictate the plants growing schedule.

What's limiting your trees's growth?

What limits plant growth?

Have you ever experienced a tree or woody ornamental that just doesn't want to grow?  Overall plant health and vitality depend on several factors, and if just one is out of whack, you may end up with an under performing plant.

It begins in the nursery

Starting with a quality plant is key for long term success.  Occasionally there are breakdowns in how the plant is cared for in the nursery that can affect how it thrives in the landscape.  During production, if a baby tree is kept in a pot for too long it may eventually form a distorted root system.  If these conditions aren’t addressed, the deformed root system will remain with the plant for it's entire life.

One common root distortion that may form is circling roots.  Circling roots are roots that grow around the stem of the plant instead of perpendicularly away from the plant.  In the nursery this happens when young roots contact the side of the pot in which the plant is growing, and start growing along the outside of the container.  Circling roots can affect plant stability.  If these roots are in contact with the stem they can lead to a condition called girdling roots.  Girdling roots have the potential to cut-off portions of a stem’s vascular system, interrupting nutrient and water flow through the plant.

At planting

There is an old saying, “you only get one chance to plant a tree.”  While planting a new tree or shrub seems intuitively easy, there are some caveats to proper planting.  All woody plants should be planted so their root flare is  at grade level and exposed, not covered by excess soil or mulch.  The root flare is the transition zone between the trunk and the roots.  Buried root flares may result in bark damage which lead to vascular system issues.  Buried root flares may also lead to girdling roots.   Note, sometimes root flares are buried due to poor nursery practices.

It’s also important to dig a hole large enough for the tree/shrub.  Standards state digging a hole at least 1.5 times the diameter of the plant’s root ball. The larger the planting hole the better.  This is so newly emerging roots have an easy time of colonizing the native soil.  The more soil that can be loosened around a newly planted tree, the faster the tree will be able to become established.

Site, site, site

Matching the right tree to the site and site preparation is paramount to overall performance of trees and woody ornamentals.  Different species have unique light, soil, and water needs.  Let’s take our native flowering dogwood as an example.  According the USDA NRCS plant materials program: “Flowering dogwood is adapted to most upland sites but grows best on rich, well-drained soils on middle and lower slopes. It develops best as an understory species in association with other hardwoods.”  So, if we are to plant a flowering dogwood in a poorly drained clay soil in full sun, it goes without saying the tree will not be healthy vigorous specimen.

One major issue we run into, especially in our urban/suburban landscapes, is damaged soils.  During new building construction the top layers of soil, which forest trees roots thrive in, are removed.  What remain are compacted subsoils.  Compaction destroys soil pore spaces that air, water, and plant roots occupy.  This is direct stress on woody ornamentals, and one of the greatest reasons trees and shrubs fail to thrive in our landscapes.  Accompanying compaction in urban/suburban soils are also nutrient deficiencies, soil chemistry imbalances, and inadequate amounts of soil organic matter.

Another major issue for plants in our landscapes is water issues.  Too little or too much water is often the difference between green and growing plants or yellow and dying plants.  Combine improper watering with poor soils and you have a recipe for disaster.

All's not lost

Fear not.  While the issues we discussed may sound overwhelming the arboriculture industry has developed some innovative protocols and tools for mending these common problems.  Laboratory soil analysis, soil decompaction treatments, and root collar excavations utilizing compressed air-tools are just a few methods available to mend adverse plant growing conditions.  If you have a tree that just doesn't seem to be growing, call your friendly neighborhood qualified arborist for a thorough assessment.

Cankerworms among us...

In the Charlotte, NC Metro area we have a big problem with cankerworms.  These inching little menaces emerge every spring to wreak leaf consuming, poop raining havoc on the populous.  Treatment for these wringing pests comes, usually, in a few forms.  Banding in the fall and early winter to capture flightless females on their trek to mate high in the canopies of trees, and foliar spraying once the chomping little caterpillars have hatched.  Both of these methods have their pros and cons.  Bands certainly do not catch every female, and in the spring newly hatched cankerworms can easily blow from trees not banded to banded trees.  Foliar sprays to control the munching larva have their own host of issues, namely getting adequate coverage on 60 - 100 feet tall trees is tough even in the best of conditions.

It is debatable how much damage is done to trees defoliated by cankerworms.  In most instances, defoliated trees create a new full canopy by the end of May/beginning of June.  This allows trees almost a full season of photosynthesis to create the energy they need and build reserves.  And hey, a few weeks of additional sunlight helps out the grass, and all of that worm poop hailing down is like free fertilizer, so look on that bright side.

Outside of being a tree pest, cankerworms can be a real nuisance.  They are constantly falling from trees attached to silk threads, and of course all that pooping.  This can make for an uncomfortable experience if your back yard is completely covered by the canopy of large trees.  My house has 2 large (+50-inch DBH) willow oaks in the rear yard.  Two years ago the cankerworm population was high enough to defoliate both of the trees by the 1st week of May.

Last year I put bands on the trees, specifically the Bug Barrier product, only to have squirrels rob the bands of the fiber used to help catch climbing females.  Once again my trees were defoliated, minus what I could reach with a foliar spray of Conserve (active ingredient spinosad).

This year I am opting for a new strategy.  Soil injection with Lepitect (active ingredient aceaphate).  Lepitect has shown great results on a host of tree pests.  It works fast to get in the tree, and has a residual of only +/- 30 days.  I like the idea of a short residual because I don't want to kill other caterpillar species that emerge later on in the season.  But here is my question, will Lepitect work well on large trees with high populations of cankerworm pests?  Hence the penning of this article.


 Follow the saga of the cankerworms below:

• March 24th
• The 1st cankerworm is spotted.  Willow oak leaves just beginning to break bud and expand.

• April 1st
• Lepitect applied at high rate, 10oz per 25-inches of diameter applied at 250ml per inch DBH.  Willow oak leaves are expanding

• April 4th
• Signs of dead cankerworms falling from trees.

• April 11th
• Approx. 18-days after emergence, and 11-days after treatment.
• Once again, a very high population of cankerworms are affecting the trees.

• April 18th
• Significant amount of dead cankerworms falling from the tree.

• April 27th
• Peak cankerworm feeding has concluded.

Conclusion:

Once again the cankerworm population was very high on the trees in my backyard.  Because some leaf feeding is required for the insects to be exposed to the product, we expect a certain amount of defoliation.  Inevitably, with instances of very high pest population we will have more leaf matter consumed.  All said and done, there was probably 40%-50% canopy defoliation when using the Smitley Scale for Defoliation.  This sounds high, but is much better than the fully defoliated trees I had the two previous years.  Additionally, the product is no longer present (or at least should no longer be present) with in the tree or the soil, so any benign leaf feeding arthropods or soil dwelling organisms should be allowed to go on with their natural life cycles.

Additional Notes/Thoughts:

I would have liked to make the application a week earlier, but my equipment for making the application had yet to arrive.  One wonders if the product had a week longer to move in to the tree, would the defoliation been less?

There were a significant amount of dead cankerworms falling over the course of three weeks.  Will this hammering of this years population have any effect on next years population?

It has been noted that the fiery searcher beetle was in greater numbers the past two springs.  These beetles are voracious predators of caterpillars and especially cankerworms.  Did these predators significantly reduce, or aid in the reduction, of the cankerworm population that in turn lead to the decrease in defoliation noted from last season?

It's all in the phenology......

Below is an article I wrote for my friends at Limbwalker Tree Service in Louisville, KY. Enjoy:

Though it may seem hard to believe, the first flowers of spring will soon be upon us.  It doesn't take a horticultural aficionado to appreciate these brightly colored petaled reproductive organs of angiosperms. The yellows, whites, blues, reds, and purples are a welcomed site after a gray cold winter.  But, the emergence of certain plant species floral displays can be the warning signs for  the appearance of diabolical plant damaging pests.  The study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation) is called phenology.

Smoke bush flowers coincide with Japanese maple scale crawlers.

Monitoring the life cycle of plants (leaf expansion, flowering, color change, etc.) has been used for centuries in agriculture to determine the appropriate timing of when certain crops should be sown.  In fact, the first record of phenology dates back to 974 BC *.  Complementing phenology are growing degree days (GDD).  GDD are calculated by taking the average of the daily maximum and minimum temperatures compared to a base temperature (usually 50°F). GDD are a measure of heat accumulation used to predict plant and arthropod development rates, such as, when flowers of a particular species may bloom, or when a particular insect will become active.

                             GDD      =        (daily high + daily low)     -   50

             2

Growing degree day charts highlighting common tree/shrub pests have been developed by the Ohio State University and Cornell University to name a few.

The use of phenology and GDD is an important monitoring tool for integrated pest management practices in the landscape.  The activity of many plant damaging pests coordinates to either the flowering or leaf expansion of common shrubs and trees, some of which may be in your backyard.  When the hanging white racemes of black locust flowers appear (500 GDD +/-), the invasive emerald ash borer adults are beginning to emerge.  The first flight of the adult dogwood borer corresponds to about 2 weeks after peak dogwood bloom (850 GDD +/-). Eight weeks after the full leaf expansion of red maple (1000 GDD +/-) the most vulnerable stage of gloomy scale appears.  These are just a few examples of using phenological indicators to predict the emergence of tree damaging arthropod pests.

Being in tune with phenology and growing degree days can be invaluable when developing a plant health care plan for our landscapes.  Knowing when insect pests are active allows arborists to make precise treatments, which limit the amount of products applied in landscapes.  This also reduces the chances of harming beneficial, or benign, critters that make our plants their home.  Happy hunting!

*University of Wisconsin

http://hort.uwex.edu/articles/phenology

Don't worry, it's not that complicated.

I'm constantly amazed at the over simplification of plant maladies that most people subscribe to.  If a tree or shrub is looking 'sick', then it must be some inauspicious bug or disease causing the problem, and a one time spray of something should solve the problem.  If not some magic spray, then the obvious solution is to 'feed' the poor starving plant.  Often we can find a tree damaging pest or signs of nutrient deficiency on our sickly patient, but it's the greater predisposing factors which are leading to the plant's decline.

Recently I was asked to look at some sickly shrubs.  Within a few moments I learned the following; when the property owners purchased the plants they got a good deal because the shrubs were old stock and not looking great (in some cases dead bark was peeling from the trunks), when installing the shrubs the planting holes were over amended with compost, and they’d been applying a complete fertilizer liberally to the root zones.  In the mean time the root balls of most of the shrubs had settled to several inches below grade.  After the shrubs started to look really bad, the property owners assumed some unknown but malevolent pest was attacking their plants, and began spraying them with horticultral oil.  My assignment was to identify what was wrong with the shrubs and develop a plan for their improved health.

The diagnosis? What was wrong with the shrubs is everything.  Substandard plants, installed incorrectly, with soil chemistry all mixed up.  There was no baleful insect or disease, just a series of preventable cultural mishaps, which so often after having occurred are left to an unsuspecting arborist to diagnose.  The remediation plan? Basically, start the planting process from the beginning, which included removing and replacing a handful of the previously installed plants.

The results of this encounter was a dissatisfied property owner left doubting the diagnoses of the consultant that was subcontracted through their primary tree care provider.  At the end of jobs like these I almost feel guilty charging my fee, and I know the clients are never too happy to pay.  Maybe next year there will be a magic potion for this.

What could be going on with this sad looking plant?

What could it be? I hope it doesn't suck....

Take a look at the picture of the Nelly Stevens holly below.  You'll notice the top of the tree is in decline.  What could it be?  Root rot? Nutrient deficiency? Perhaps straps where left around the stem and are now girdling the tree...

Now let's take a closer look...

Upon closer inspection we see the top die back is being caused by coalescing sap sucker wounds.  The yellow belly sap sucker drills holes in over 1000 species of trees.  The purpose of this behavior is to feed on the high sugar content tree sap, and any insects that may get caught in it. Sap suckers form two kinds of holes.  The first is a round hole that extends far into the tree and is not enlarged.  These are the holes that are commonly associated with species like sugar maple.  The second is a square hole that is shallow, but which needs to be be constantly maintained for sap flow.  It's this square hole that I've seen kill whole branches of trees over the years, most notably holly species. 

There aren't any good ways to prevent sap suckers from enjoying your trees.  Repellent sprays on the market seem to not be effective.  For high value trees I've seen burlap being wrapped around trunks during times of sap sucker activity.  This provided some modicum of protection, but can be unsightly and labor intensive.  In the interest of political correctness, I'll refrain from any BB-gun jokes.

It starts at Day 1

When we take a tree from its native environment and plop it in the middle of the landscape, we're taking on a lot of responsibility.  The seemingly simple step of planting a tree can be the most important moment for the plant over the course of its life.

In the picture below are two oaks planted at the same time and at the same size.  The tree in the left of the picture was planted with the root collar exposed and at the proper grade.  The tree to the right was planted with root collar well below grade.  Several years down the line the correctly planted tree is far out performing the improperly planted tree.

The precedent for how these trees will function in the landscape was set on the day they were planted.   Proper planting, soil moisture, soil texture, etc. all play a part in how our trees will survive. Attention to detail is important to the long-term success of any introduced tree in our landscapes.

Zombie Tree

One theme I can't emphasis enough is that trees don't want to die.  Over millions of years, these large woody plants have found ways to overcome all kinds of ordeals.  We often try to predict tree failure and mortality by quantifying visible and perceived damage.  If said damage exceeds some measurable threshold, then that tree is often slated for removal.  But trees don't always fall in line with what we think is so certain.  Take for instance the tree pictured below.

At some point in time this tree met with some accident.  Significant area of trunk circumference was damaged.  Upon initial inspection, most of us would probably not give this tree much chance of survival.  Now there is no telling how long ago the damage occurred, but if you look closely you'll see the extensive amount of wound wood growing over the damaged area.  Some may say this is unprecedented, but I say it's a tree showing us that there are exceptions to every rule, and those exceptions seem to be exceptionally common in arboriculture.

The arrows highlight areas of the tree where wound wood is forming around extensive trunk damage exceeding 30%  of trunk circumference.

Tippy trees.

Some trees lean.  Leaning trees are a natural phenomenon in nature.  While there are many reasons why trees lean, most of the time the reason involves the search for light.  This is called a phototropic growth response.  Trees growing in this manor put on adaptive growth and reaction wood to maintain stability.

Once a tree has grown to a point where there is a clear view of the sky the lean will 'self correct,' and new growth will begin to grow with a more vertical orientation.  At this stage the stem lean should be at its maximum, and if the tree remains structurally sound the angle of the lean should remain constant.

Look carefully at the pictures below.  The picture on the left is a screen shot from Google Street View of a post oak taken in 2011.  The 2nd picture is of the same tree taken in December of 2013.

2011                                                                                       December 2013

Notice the difference in orientation of the lean.  The root collar of this tree is not well exposed.  The homeowner indicated she noticed a change in the lean of the tree in July of 2013, and was aware of at least one 3- to 4-inch diameter root that was severed to install the brick walkway earlier that same year.  After some peripheral probing with a soil knife to about 6-inches deep, no structural roots were detected on the tension side of the lean. 

Could this tree be actively failing, albeit slowly?

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.

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.

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.
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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.  

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.

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.

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.

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.

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.

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.

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.