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.

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

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.

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.

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 

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: http://www.guardian.co.uk/lifeandstyle/2013/apr/28/nine-gardening-myths-debunked?INTCMP=SRCH  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.

'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.

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.

The Root Collar, Oh No

By now we all know trees in the landscape, big or small, should have an exposed root collar. The root collar is the area of the lower trunk that flares out at ground level.  It is the transition area between the stem and the structural root system of a tree.

Tree root collars have evolved over eons to be exposed to air.  Buried root collars are detrimental for several reasons.  Cell respiration is disrupted, adding just one more stress to the tree.  This area of the tree can be intolerant to prolonged soil moisture, which can decompose tree bark and give way to stem pathogens.  Finally, buried root collars can lead to and disguise stem girdling roots.

Stem girdling roots arise in a few ways. When root collars are buried the tree reacts as if part of the root system has been damaged, and the tree forms a secondary root system.  These secondary roots can grow parallel to the stem, and begin girdling.  The other danger in this scenario, the secondary root system may take over water and nutrient uptake for the tree while the primary/structural roots slowly rot away.  Thus, a tree that looks perfectly healthy is standing with little to no structural root system.

Another way girdling roots develop on our landscape trees is through container production.  Many of the trees we plant are started in pots. When trees are allowed to stay in these pots for too long roots interact with the sides and begin circling the container. In many cases this is allowed to happen through every change in pot size, creating an almost hopeless structural root system.

With all that said, here are some pictures of messed up root collars and girdling roots:

Girdling roots around the circumference of the lower stem.

Large impacted girdling root, notice the diameter of the root compared to the diameter of the stem.

Severed girdling root, notice the large amount of stem damage that has occured.

What would you do for Liberty?

In 2010 an unknown assailant attempted to cut down a young tulip poplar in Charlotte's Freedom Park.  The vandal made it half way through the trunk before giving up.  While I know how many arborists feel about tulip poplars, this one was different.  This tree was grown from the seed of Maryland's original Liberty Tree.  You can read more about that story here: http://thequeenscrown.org/locations/6/Freedom-Park-Tulip-Poplar .

The Liberty Tree Tulip Poplar in the Summer of 2012

In an attempt to save the tree, horticulture staff installed guys in the direction of the damage and fastened steele plates adjacent to the cut.  Tulip poplars are fast growing trees, especially when young, and the idea was by stabilizing the trunk the tree will form reaction wood and grow over the damage.

After 2 years, see the amount of growth already put on by the tree.

Many of the prejudices we have about tulip poplars come from working on forest grown trees that suddenly find themselves in the middle of a suburban development.  Open grown tulip poplars can develop massive trunks with good taper, and are usually not as tall because reduced competition for light.  We think of tulip poplars as poor compartmentalizers, but the speed at which decay moves is relative, and may take decades to effect a tree that is today young and vigorous.

What would you do?  Would you have just removed it and said 'oh well.'  I think the horticulture department did the right thing, and because of these efforts we'll have an interesting tree to enjoy for years to come.

The Scourge of Imidicloprid

If you're like me, then while your wife is looking at power tools at Home Depot, Lowes, or wherever, you are looking at the active ingredients on pesticides in the garden aisle.  Which means you have probably noticed that many general purpose over the counter insecticides are now imidacloporid based.

As an industry, we have relied on imidacloprid, Merit in its most popular form, for more than a decade.  Applied properly it is a great product.  It is in the neonicotinoid family of chemicals, and its mode of action is kind of neat.  The chemical interferes with an insects nervous system which results in death. Imidacloprid can be applied as a foliar spray, soil application, or directly injected into the trunk.  It is nontoxic to mammals, has a long residual, and can be quite effective.

However there are some things we need to consider when using this pesticide.  Studies have shown that with repeated use the molecule can make its way into the flowers of plants.  For trees and shrubs that are not wind pollinated this exposes pollinators to the product, and may lead to civilian casualties in the war against plant pests.

The other issue is pest resistance to imidacloprid.  In some areas imidacloprid has been so heavily used that it is no longer effective against targeted pests.  With imidaclolprid now being readily available to the public at large, and continued reliance on the chemical in many professional PHC programs, we may only assume that this pest tolerance will grow.

There are few 'silver bullets' in pest management.  Product/chemical diversity is an important part of an IPM program.  Imidacloprid may still be part of your chemical arsenal  but pest monitoring and investigating different products for use on target pests should be on the forefront.

The molecule

The Mystery of the 'Toe'

It's the holidays, and around this time of year I can't help but think about  mistletoe.  That's right, mistletoe.  Mistletoe is the common name for over 20 genera of obligate hemi-parasitic plants of trees in the order Santalales.  Mistletoe still photosynthesizes to create carbohydrates for energy, but it uses structures called haustorium to penetrate tree branches, where it then absorbs water and nutrients directly from the tree. With heavy infestations comes tree decline, and affliction with mistletoe can contribute to tree death.  Branches with mistletoe can also become quite brittle.

Hickory branches afflicted with mistletoe.

The berries of mistletoe are a food source for many species of animals like birds, and is how the plant is distributed through out tree crowns.  Birds either wipe the berries from their beak on to branches, or the seeds survive ingestion and are distributed through bird droppings (poop). The berry itself is extremely sticky when squished.  Most mistletoe flowers are insect pollinated, but some have huge showy flowers which are bird pollinated.

Sticky toe berries.

Now if you thought all of that was interesting, the myth of mistletoe is something else.  Apparently the Norse god Loki tricked the blind god Höðr into killing his brother Baldr with a mistletoe arrow.  This was after Baldr and Höðr's mother, the goddess Frig, failed to get an oath from mistletoe to not harm Baldr.  She never asked mistletoe take the oath as it seemed 'too young.'  Lesson learned.  After bringing Baldr back to life, Frigga declared no harm could come to one standing under mistletoe.  Another myth states mistletoe was the wood that Christ's cross was made of, and after the crucifiction it was destined to live the rest of eternity as a parasite. 

Mistletoe is most famously sacred to the ancient Celtic Druids.  After sacrifices, mistletoe would be passed out, and the recipients were thought to have good fortune.  Mistletoe was thought to be the soul of the oak, and was collected at the summer and winter solstice.  It was also thought of as a sexual symbol.  Druid beliefs were adopted by early Christians and mistletoe was hung in homes to ward off demons.  This is where the modern practice of decorating with mistletoe during the holidays came from.

The Greeks had their own mistletoe tradition, and the plant was used during early marriage ceremonies as a sign of fertility.  This, combined with the Scandinavian tradition of standing under mistletoe as symbol of truce with enemies, is probably were the modern Western European kissing tradition evolved from.    

So mistletoe is pretty interesting on many different levels.  A word of warning though, if your mistletoe is allowed to touch the earth then it looses it's mystical powers.  Happy Toe hunting, and happy holidays.     

Toe harvesting is easiest done by aerial lift truck.

   

Lint Bug: The Aphid Wolf

Have you ever seen a lint bug?  Up until a few months ago I thought they were inconsequential, but cute,  little insects living on tree trunks.  I never really thought about what they ate, or their role in the ecosystem.

While doing research for another assignment I came across an article about lint bugs, and found they are brown lacewing larva.  As many of us know, green lace wing larva are voracious predators of many arthropod plant pests, and so are the larva of their brown winged cousins.  One web-site even referred to them as Aphid Wolfs.  They carry debris on their back for camouflage, and interestingly enough, some of that debris is actually body parts from their victims.  I might have a new favorite insect.

That gray pile of debris is a lint bug in a sea of  gloomy scale.

I snagged this close up picture from www.whatsthatbug.com

Red Maples: What a Bummer

By some twist of arboricultural fate I was charged with doing an 800 tree inventory this past week.  About 60% of the trees were.... you guessed it red maples.  Of these not one was with out co-dominate stems combined with some kind of defect.  Be it girdling roots, buried root collar, gloomy scale, or all of thee above.  Lets take a pictorial look at the mayhem.

So many co-dominate stems all coming from the same area on the tree.

A crack in the stem originating from co-dominate stems and leading almost to the ground.

Gloomy scales piled upon gloomy scales feeding upon there victim.

More sever cracks originating from co-dominate stems.

Of course a pictorial account of red maple defects would not be complete with out some impacted stem girdling roots.

Multiple upright branches with associated storm damage.

Left unattended since planting, these trees have become a maintenance nightmare.  Young tree pruning and proper planting are paramount, and this tree inventory is a prime argument.  To correctly mend these issues this home owners association will be looking at more than a $50,000 price tag.  Red maples, what a bummer right?

Irrigation and Poor Drainage

Last week I wrote about the importance of water management, and the difficulty of getting it right in poorly drained soils.
This picture illustrates that point perfectly.  The arborvitae that looks the worst is sitting in the lowest spot of the planting area.  Drip irrigation is present, and run diligently a few times a week in a heavy clay soil.

Wax Scale

Here a picture of an Indian wax scale on a white mulberry.  Wax scales are interesting, as they are all female. That's right no males. It's kinda weird.

In mass, wax scales can stress out a tree or shrub, and produce copious amounts of honeydew, though I have seen neither.

The best management strategy is to simply pick them off in winter.

Compacted Soils

There is no question that trees growing in compacted soils generally won't grow as well as trees in a lower bulk density soil.  Compacted soils adversely affect root tip elongation, affect gas exchange, and disrupt water availability.

In the latest edition of Arboriculture and Urban Forestry a study performed by Barbara A. Fair, James D. Metzger, and James Vent  concludes  water availability in compacted soils may be the limiting factor for tree growth.  They found carbon dioxide levels were 5-18 times higher in compacted soils compared to atmospheric concentrations, while O2 concentrations were similar to atmospheric levels despite density.

This tells us that water management is increasingly important in our urban landscapes.  Often tree owners tell me they irrigate, but the irrigation is usually too little or way too much based upon the site.  Getting the correct amount of water in compacted soils can be a tricky code to break.  Think of a line of plants along a slight grade change.  Many times you will see the trees on the high side parched for water, while the trees in the low area are sitting in saturated soils well above field capacity.