We all know how weather affects plant diseases: Warm, moist conditions are perfect for the growth of plant pathogens.  But that’s not what this article is about.  This article is about how plant pathogens can affect the weather.

But before we get into that, we need a little background information on the chemistry of how ice forms.  (Trust me on this one.)  Most people consider 32°F to be the freezing point of water, and generally speaking, this is true.  Technically, however, 32°F is considered to be the melting point of water.  This is because pure water, really pure water, often experiences supercooling; not freezing until it reaches temperatures as low as -40°F.  This is because at temperatures just below 32°F more than 100,000 water molecules need to latch together before an ice crystal becomes stable enough to grow on its own.  The chances of this many molecules randomly coming together to form an ice crystal are exceedingly low, even at colder temperatures.  In our everyday world of puddles, ponds, and ice cube trays, tiny particles of dust and such act as a template for the hexagonal lattice of an ice crystal to form on, triggering ice formation at 32°F.  This process is called “ice nucleation.”

Climatologists have been aware of this for decades.  They have long assumed that tiny dust particles blown up from the earth’s surface into the atmosphere induce ice crystal formation in clouds, triggering precipitation.  (Only ice crystals grow fast enough to reach the critical mass necessary to fall from the cloud as rain or snow.)  But they have never been able to identify which of the many types of dust particles have the right surface chemistry to act as the ice crystal template.

Enter Pseudomonas syringae.  P. syringae is a bacterium that causes disease in a wide variety of plants.  It also produces proteins on its surface that make it act as a “biological ice nucleator,” triggering frost formation resulting in injury to plants.
Ice crystals forming on the plant rupture the cells, making the nutrients within available to the bacteria.  P. syringae, along with a host of other bacteria, fungal spores and algae, get blown up into the atmosphere along with all that dust that
climatologists have been studying, and may be the true source of ice crystal
formation in clouds.

Is this just happenstance, or is it an evolutionary strategy?  Are bacteria rising into the atmosphere to trigger rain to produce more plants to feed on?
Are forests making more rain by releasing bacteria into the atmosphere?

And what about us?  How can we exploit this extraordinary characteristic of an organism we have long considered a “pest?”  The Biosciences Division of the U. S.
Department of Energy has supported considerable work on P. syringae.  There is promise in its use in freezing foods.  It has been used in the production of artificial snow for skiing and artificial ice for skating rinks.  It has also been used to create
artificial ice islands in cold oceans to facilitate oil drilling, and research is being conducted in using it to produce mountains of artificial snow to use for summer cooling.

So, while I hate to see Pseudomonas blight on my lilacs, the more I learn, the more I realize that nothing in nature is all bad.

April 1, 2012 marks our 25^th year in business!  I’ve met a lot of interesting people in that time and seen a lot of changes to the industry as well.

 I’ve had the opportunity to work with some great folks in that time, most notably Christopher Haynes and Adam Bumpus, my current “go to” guys.  Who could forget Steven Bagley and Adam Braaten, currently with Bartlett Tree Experts in the Mid-Atlantic Region?  Chad Hart and Patrick Morse both went on to eventually start their own businesses.  Chad and I are currently collaborating on our second Arbor Day project at the Palmer Arboretum in Woodstock, CT.  Chad gets all the credit for organizing this event.  Last year was a great success!

I’ll never forget the day Matt Burdick went up a tree to rescue an escaped parrot. All the local media was there to capture the moment.  The parrot just didn’t want to come down.  Matt offered food and his own perch stick, but no go.   Matt finally got close enough to grab him, but the defiant parrot bit him through his thick leather gloves, drawing blood!  Matt eventually stuffed the bird into a knapsack and brought him down safely.  He was the hero of the day!

 Some of my best experiences have come about through my involvement with industry organizations.  Volunteering for the Massachusetts Arborist Association’s Certified Arborist Examining Committee and the American Society of Consulting Arborists Board of Directors has given me the opportunity to befriend some of the most innovative and influential members of the Arboricultural community.  These are good
people whose friendships will last a lifetime.

Looking back, some of the equipment I started out with seems antique now.  The Morbark Eager Beaver brush chipper I bought in 1987 was state of the art at the time.  Now it looks downright silly parked next to the modern day machines we run today.
But it still runs like a top and I keep it around for a spare.  The equipment we use has changed dramatically over the years.  The chippers are safer to operate, the chainsaws are lighter yet more durable, and the vehicles are more efficient and cleaner running.

 The materials we use to control pests have evolved as well.  The insecticides and fungicides in use today have moved from targeting basic biological functions that affect a broad range of life forms to targeting metabolic pathways specific to the pests they control, making them safer for the environment, the public, and the applicator.  I like that last part a lot!  In the “old days” we would have addressed problems like the Asian Long Horned Beetle and the Emerald Ash Borer with broad spectrum cover sprays that would kill anything that landed on the tree.  Today, we have systemic insecticides that zero in on these imported pests.

The biggest changes in Arboriculture have come about in how we look at ourselves as an industry.  Arboriculture has moved from a trade to a Profession, with a capital P.  We are funding research to ensure that the treatments we apply to your trees are based on sound, modern science.  Organizations like the TREE Fund bring arborists and the public together through programs like the Tour Des Trees, which brings sponsors together with volunteer arborists riding a 500 mile bicycle route each year to raise funds to support research, scholarships and educational programs in the fields of arboriculture and urban forestry.

And we have come to realize that, while it is a dangerous Profession, we can perform our work safely through proper training and using the personal protection equipment that is now available.  It is no longer acceptable to send just anybody out to “get the job done.”  Our clients are more educated about sustainable practices and demand
that educated, well trained, professional crews perform the work on their properties in accordance with current safety and Arboricultural standards.

A lot has changed in the last 25 years, and it has been a good run.  I can’t wait to see what the next 25 years brings.

Last week the American Society of Consulting Arborists (ASCA) held its annual conference at Incline Village, NV on the shore of beautiful Lake Tahoe. The ASCA staff has a knack for choosing some of the most beautiful locations in the country to hold our conferences, so as usual, we spent a few extra days to take in the sights.  Coming from the east coast, I’m always awed by the trees our western members get to work on every day.

This six-foot diameter Incense Cedar is a good example!

ASCA Conferences are known throughout the tree care industry for their exceptional educational programing, and this year was no exception.  Dr. George Hudler from Cornell University gave an excellent presentation on Phytophthora disease on beech trees.  Attorney Hailey Hibler conducted a mock deposition to help train ASCA members in their roles as expert witnesses.  Scott Steen discussed how enhancing our urban forests can save energy.  For example, the city of Sacramento, CA determined that it could reduce the heat island effect by 3 degrees Fahrenheit by doubling its urban forest canopy, a goal that includes planting two million trees.  So far, they have planted 450,000 trees and reduced energy consumption by two million kilowatt hours per year!

I can’t cover the entire program in this post, but rest assured that it was as exciting and informative as could be.

Next year’s conference will be held in San Diego.  I can’t wait!

We all know that trees go by two names; their common names and their botanical names (often reffered to as their Latin names, which I eschew because many of the names are derived from Greek as well).  We’re all familiar with common names that describe our trees such as flowering cherry.    But what’s with these botanical names?  Even if you can manage to get a pronunciation out, it all sounds like gibberish!  What do we need those for?  Well, as we saw in my April post on shadbush, also known as serviceberry, some trees can have more than one common name depending on where you come from and what characteristics you choose to describe with that common name.

Botanical names were devised to provide a standardized nomenclature that everyone everywhere could use to talk about their trees without confusion.  For example, for me, red maple means Acer rubrum, but lots of folks call them swamp maples, because, in their minds, red maples are those maples that have red leaves in the summer, Crimson King Norway maples, Acer platanoides ‘Crimson King’.

As crazy sounding as those botanical names sound, they do have meanings that are very descriptive of a plant’s characteristics.  The genus name Acer, for example, comes from the latin word acer meaning bitter, sour, sharp, or pointed.  Its the pointed meaning that applies to maples, describing the pointed tips of the leaf’s lobes.  (Thanks to collegue Alby Thoumsin for helping me figure that one out!)  And rubrum means red, to describe the fall color of the leaves.

OK, so I agree it can get a little crazy.  How about this one: Gleditsia triacanthos inermis. The genus name, Gleditsia, is a tribute to the German botanist Johann Gottlieb Gleditsch.  Not exactly a descriptive of the plant, but interesting none the less.  The specific epithet triacanthos, the second part of the name that refers to the species, means three-parted thorns, describing the tree’s thorns that are not just a single prong, but produce three levels of branching.  The suffix inermis indicates that this variety is thornless.  So, this is a thorny tree named after a famous botonist that has no thorns!

So next time you are searching through your nursery and garden catalogues, don’t ignore those botanical names, they can tell you a lot about the plants you are looking at.  There are many websites that provide dictionaries of specific epithets.  Here’s one:  http://www.nargs.org/nargswiki/tiki-index.php?page=Dictionary%20of%20Specific%20Epithets#p http://tomclothier.hort.net/page37.html

I haven’t found any dictionaries of the meanings of genus names.  To understand these names I do etymological searches of the name on websites such as these:  http://www.etymonline.com/index.php?search=acer http://www.myetymology.com/

If this all gets to be too much to bear, check out this fun article for a sanity check:  http://tomclothier.hort.net/page36.html#C

Fall color on a young eastern white pine.

Its that time of year when I start to get frantic calls from clients worried that their pine trees are dying.  “The needles on my pine tree are turning yellow and falling off,” is the usual distress call.  But this is normal fall color on evergreens.  Evergreen trees are not evergreen because they never loose their needles, but because the needles remain on the tree for several years before falling off.  Every spring a new set of needles is produced on the new growth, and every fall the oldest needles turn color and fall off, just like the leaves on their deciduous counterparts.  Depending on the species of tree, the needles can last from two to four years before their useful life expires. 

So, if you see needles on your evergreen trees turning color this fall, don’t panic!  Look closely.  If the needles turning color and droping are the oldest needles furthest in on the branches then you are experiencing yet another variation of our wonderful fall experience.

The older, interior needles turn yellow and fall while the newer needles at the tips of the branches are retained for the next season.

A few years back, I had the opportunity to go to Kauai, Hawaii.  I have always been fascinated by Hawaii; in the fifth grade I did a report on Hawaii, writing to the Chamber of Commerce and tourism agencies to gather as much information as I could about the state.  There was no internet in those days, but I got an enthusiastic response from the folks promoting the state’s virtues. 

When I finally got there 45 years later, I was not disappointed!  Something was in bloom everywhere!  We were staying in a cottage at Waimea Plantation, surrounded by pomegranate, banana, and star fruit trees.  Fifty foot tall Plumeria trees perfumed the air with their pinwheel shaped white flowers. 

A short walk from the cottage brought me to a secluded beach where I could bathe bare to the world.  “Swimming” entailed standing shin deep in in the lukewarm Pacific water while 8 foot waves broke over my head.  All was good.

One night, while laying on the beach, looking at a Milkyway that I had never seen before, I schemed how to get my dog to Kuai so that I would not have to go back to Connecticut.  But, alas, the vacation ended. 

It was mid October when the last leg of our return flights landed in Providence.  The landscape was ablaze in fall color.  I was overwhelmed!  For all of the exotic flowers and fruits on the Islands, there is nothing like this in Hawaii!

Sorry I’ve been away from the keyboard again.  Its just been crazy busy around here for the last month or so.  Just when we were getting caught up on cleaning up damages from the June 1, 2011 tornado that hit Massachusetts (here is a link to photos of the damage, don’t miss the aerial photos beginning on page 9: http://www.wellfleetosprey.com/Other/TORNADO-JUNE-1-2011/17485276_9v8zLR/16/1352807981_Wtv2Mgc#1330773729_42QLcVG) and the severe thunder storms that hit our area in the following weeks, we were hammered by the remnants of Hurricane Irene.  To make matters worse, Irene struck two days before I was scheduled to travel to Berkley, CA for a meeting of the American Society of Consulting Arborists Board of Directors.  It was a commitment I had to keep.  Fortunately, our team of Chris Haynes, Adam Bumpus, and Mike West had things under control, providing prompt service to our clients most in need.  Kudos to those guys! 

While we still have a heavy backlog of work to catch up on, things are normalizing again, so I thought would make a post. 

It looks like the fall colors will be pretty dismal around here.  With such a wet season as we have had, just about every kind of tree has been infected with some type of leaf spot disease, causing the leaves to drop prematurely.  Most of the red maples (Acer rubrum) in my back yard are half defoliated already, and the remaining foliage is turning with weak colors. 

Most of the sugar maples, the signature fall foliage plant in New England, have been infected with Anthracnose, leaving them with brown and shriveled leaves that won’t amount to much, color wise.  Our poplars, noted for their brilliant, golden-yellow fall color are just about completely defoliated, as are many of our white ash trees, which often contribute purplish hues to the fall landscape.

The TV Meteorologists alwas make a big deal about peak fall color, But I have always considered there to be three peaks.  The red maple peak, which comes first, followed by the sugar maple peak that TV guys like to crow about, and lastly, the oak peak, a subdued but long lasting show of muted crimsons, golds, and browns that look best in setting sunlight.  It looks like the oak peak will be the star of this year’s fall color show as the oaks around here seem to have fared well this year with regard to leaf diseases. 

On another note, the Massachusetts Arborist Association held our fall Certified Arborist Exam on Friday, September 30.  As Chair of the Examining Committee, I am happy to announce that about two-thirds of the 35 or so candidates passed the exam.  Congradulations to our newest MCAs.  As a member of the Committee for the past seven years, I have witnessed the Committee’s commitment to improving the Certification process through developing a Study Guide CD and redesigning the exam.  Our goal is to ensure that the public has access to quality tree care services by selecting tree care companies that employ Massachusetts Certified Arborists.  The Massachusetts Arborist Association plans to launch Version 2 of our study Guide in early 2012, with an improved exam format for the Fall 2012 Exam.

 If you want to know what pests to look for in your yard this month head on over to this site:   http://umassgreeninfo.org/landscape_message/landscape_message.html.

That’s all for today.  I hope to be back soon.

Well, its that time of year again.  Crab apple trees are loosing their leaves leaving bare, unattractive trees in front yards, birch trees are dropping leaves like rain, and soon I will be receiving calls about the large black spots that develop on maple leaves.

These diseases are what we arborists generally lump together as leaf spot diseases and are very common when we have wet spring seasons like we had this year.  The fungi that cause these diseases infect the leaves of trees early in the season, usually when the leaves of the affected trees are just expanding.  The leaves and fungi mature together until the fungi reach their reproductive stage, when they begin to produce spore producing structures.  These are the leaf spots we see on our trees that cause the premature leaf drop that alarms so many of my clients.

With apple trees, apple scab and cedar-apple rust cause premature leaf drop in July.  Giant tar spot on maple causes large black spots on the leaves of maple trees that can result in early leaf drop of maple leaves in August and September.

Most of these leaf spot diseases are more of a cosmetic problem than a health problem for the affected trees, although repeated defoliation of trees can weaken the tree over time. 

By the time most of us see the damage to the tree, it is too late to treat the problem.  The only way treat leaf spot diseases is to make preventive applications in early spring when the fungi are infecting our trees. 

While I have an established spray program to control apple scab and cedar-apple rust on apples because of the severe effect these diseases have on the aesthetic value of these trees, most leaf spot diseases don’t require any treatment at all.  The minimal effect on the health of the tree and its aesthetic contribution to the landscape just don’t warrant the cost and effort to control these diseases.

So, if you see spotted  leaves dropping early from your trees this time of year, don’t panic!  Its just a result of the wet spring we had and your trees will be fine next year.  If you are unhappy with the way your trees look this time of year, consult with your arborist to set up a preventive spray program next spring.

I always get a strange look when I recommend that my clients water their trees. There is a common misconception that trees have these enormous, deep root systems that penetrate to the water table and are immune to drought. But with the typical tree, most of the tree’s absorbing roots are in the top 18 inches of soil, and when this soil layer dries out, the trees become drought stressed.

Just today I had a client ask, “With all the rain we have had this spring and all the snow melt, do you really think my tree needs watering?” My answer was an unequivocal “Yes!”, and to illustrate, I pulled out my trusty soil sampling probe. It was difficult to penetrate the baked-dry soil, but the 12 inch soil core I pulled up was powder dry.

Soil dries out quickly once it stops raining. What isn’t taken up by the plants or evaporates from the soil surface drains through the soil beyond the reach of most trees’ roots. A good rule of thumb for New England is that we need an inch of rain per week throughout the growing season to keep trees at optimum growth. While most trees can tolerate missing the full dose of water for a couple of weeks, valuable trees, or trees already exhibiting signs of stress, should be irrigated when the soil dries out.

So, how much water should you apply? One inch of rain equals 625 gallons of water per 1,000 square feet! It is best to apply this water in a single session so that it can soak deeply into the soil. I understand some people’s concern about the cost of pouring that much water on the ground, but I can only advise you as to what is good for your tree, not your budget. Another concern is running a well dry. Using soaker hoses instead of sprinklers slows the draw on the well and also allows the water to slowly soak into the soil; a win-win situation for both your well and your tree. If you do use a sprinkler, you can tell how much water to apply by simply placing an empty tuna fish can under the sprinkler. When the can is full, you are done!

Drought stress is the most common factor that predisposes trees to insect and disease attack and premature death. If you value your trees, get that hose out and start watering. Its DRY out there!

I get a lot of calls from clients about trees that “don’t look well.” Upon inspection, I often find trees with thinning tops, the branches dying back from the tips. Whenever I see these symptoms, the first place I look is to the root crown, the portion of the tree at ground level where the trunk transitions into the root system. Any damage to the root system or root flair will disrupt the flow of water and nutrients to the above ground portions of the tree. Symptoms of this type damage typically show in the top portions of the tree first.

The disruption can be caused by root loss caused by construction or disease, or root suffocation because of being buried too deep or excessive water. These can often be difficult to diagnose because the problems are buried deep in the ground. So the first thing I look for when I see these symptoms is girdling roots – roots that encircle and strangle the trunk of the tree. Girdling roots seem to be most common on maples, but can be found on any type of tree.

Girdling root can occur naturally, but usually arise from human influences. Container grown nursery stock that is left in the pot for too long develops roots that encircle the inside of the pot. If these are not removed at planting, they will begin to strangle the trunk when it grows to the diameter of the container size. It is amazing how many Japanese maples I see suffering from girdling roots when they reach 8 inches in diameter, often the size of the first container they are grown in. Another common cause is planting or mulching a tree too deeply. The excess moisture in the soil or mulch can cause adventitious roots to grow around the buried part of the trunk, often encircling and girdling it. One study I read indicated that Norway maples, which are particularly prone to girdling roots, respond to root pruning in the nursery by producing root branches that emerge at 90 degree angles from the parent root. These then become girdling roots.

A healthy tree will have a natural root flare where the trunk meets the ground. This is the point where healthy roots radiate out away from the trunk and into the soil. If your tree has a trunk that appears to go straight into the ground like a telephone pole, or appears to have no root flare on one side, in my have girdling roots. Girdling roots are often visible at the soil surface, but you may have to dig from a few inches to a foot below ground to find them. If detected early enough, and the constriction is not too severe, the problem can be solved by severing the offending roots, however, trees with large, embedded girdling roots often cannot be saved.

This Norway maple was strangled by its own roots. The buried girdling roots,exposed during the stump grinding process, totally encircled the trunk of the tree.