The Chemistry of Fall Color

The spectacular seasonal color display staged by deciduous trees as they prepare for winter has long been regarded by many as the peak period of beauty.  Resort areas in locations where leaves are especially brilliant do a brisk business in September and October. Homeowners and professional landscapers frequently select and plant trees on the basis of their fall display alone.
Several chemical processes are at work determining leaf color and intensity. Photosynthesis, the food-making process of the leaf, utilizes sunlight and the green pigment, chlorophyll, to manufacture sugars.  This pigment is chemically unstable and is constantly being both synthesized and broken down. We will talk about three basic color pigments: Green, Yellow and Red; all are created by the plant at different times throughout the year and are found in various concentrations within the leaf.
Green chlorophyll is present throughout the growing season and is so plentiful, that it masks the presence of the two yellow pigments that are manufactured shortly after the leaf unfolds. Unlike chlorophyll, these yellow pigments are chemically stable and remain in the leaf throughout the season. The red pigments in a leaf are not synthesized until late in the growing season and their creation is dependent upon high sugar and tannin concentrations in the leaf combined with bright sunny days followed by cool nights.
Many people ask why the same tree may have different intensities of color from year to year. This is because the red pigment content is highly dependent upon weather conditions and can vary greatly from year to year.  Furthermore, these red pigments are water-soluble and are primarily located in the upper portion of the leaf, thus obscuring the yellows either partially or totally, depending upon concentration.
Contrary to the widely held belief that leaf color change is produced by early fall frosts, a combination of bright days and cool night sets the chain of events in motion that results in the brilliant shades of autumn.  By fall there are approximately three hours less of sunlight than during the height of summer, and light rays tend to be reflected rather than absorbed. These changes result in a reduction in photosynthesis that results in a reduction in chlorophyll production.  Within a short time, this unstable green pigment (chlorophyll) already present in the leaf breaks down, and the underlying yellow pigments are revealed.
At the same time, the combination of shorter days and cooler temperatures trigger the formation of a thin wall of cells where the leaf is attached to the twig, effectively shutting off the flow of water and bringing to a halt further sugar and chlorophyll production.  Unless red pigments are present, the leaf will appear yellow.  Brilliant shades of red will predominate in some species, however, if the days have been sufficiently bright to produce large quantities of sugar and the nights sufficiently cool to trap it within the leaf.  Intermediate hues between yellow and red represent a blending of pigments
Other factors that play a role in the development and intensity of fall coloration are the tree’s exposure and elevation, genetic makeup, and the prevailing soil conditions.  More intense color can usually be found on plants growing in full sun, and often the western side exposed to later afternoon rays will be more brilliant.  Trees growing in low-lying areas where cooler night air settles will be the first to show color. Soil conditions such as pH and relative fertility determine color to some degree, as nutrients taken up by a tree are utilized in the synthesis of the leaf pigments and sugars.

We are fortunate to live in the Northeast where this seasonal display happens each year. Make some time this fall to go out and enjoy this biochemistry in action!

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Spring is around the corner. This will be the time of year when people get outside and start to do yard work. If you plan on mulching this year, take a quick look at this informative photo – There is a right way and a wrong way to apply mulch.


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Deicing Salt and Trees

With the new ice coming, I thought it would be a good idea to update and repost this article I wrote; As all the snow and ice starts to melt over the next few days, the next worry is having your trees get flooded!


It’s snowing in the Lehigh Valley (Eastern, PA) and thoughts of shoveling and plowing are dancing in everyone’s head. It’s only natural to want to do as little of these activities as possible and that’s where the application of de-icing salt comes in. The more we salt and sand the walkways and driveways, the less shoveling we may have to do! As we get knee deep into the snow and sleet season, it’s a good time to talk about salt injury to your plants.

As you might expect, the damage is more common along walkways, driveways and roadways, but what exactly is salt anyway?

Salt (NaCl; sodium chloride) is commonly applied as a deicing mixture on streets and sidewalks and can cause damage to many of your trees and shrubs. The damage results when salt, dissolved in runoff water, either enters into the root zone or comes in contact with foliage in the form of spray created by passing vehicles. Symptoms of salt injury may not always be well-defined and often resemble those caused by other adverse environmental factors, particularly drought or air pollution. Affected plants commonly exhibit some or all of the following symptoms:

  • Delay in leaf budbreak flowering
  • Stunted foliage
  • Reduced shoot growth
  • Leaf and Needle browning.

Injury is most pronounced on the side of the plant facing the salt source and, particularly on evergreens, on lower branches that can get “salt spray” from passing traffic. Salt causes a “burn” to the roots and foliage it comes in contact with. This results from the natural movement of water from an area of lower salt concentration within plant cells to one of higher concentration in the soil or on foliar surfaces – causing the water to be literally “pulled out” of the plant. Another way that salt is considered to be harmful to plants is in the sodium ions themselves. Sodium concentration in plant tissues may alter a plant’s mineral nutritional balance and inhibit protein synthesis and other biochemical processes.

As you can see, most of the symptoms become obvious in the spring, so prevention is the best strategy. When shoveling snow, try not to pile it up near the root system of a tree – this might be the best prevention stratgey of all! If you do see any symptoms like the ones noted above – the first step is to water deeply and try and leach out any salt; the second step is to call your Arborist!

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3 Success Skills…


Along with being an Arborist, I am a science teacher. I believe in putting students on the path to success and not only teach the science curriculum, but also “life lessons” that will help students to succeed in all their subjects. There are 3 skills that I have found are important for success and as the new semester starts, I thought I would repost this from a couple of years ago.

The start of every school year brings optimism and enthusiasm for success. Some students even promise themselves that this will be the year they buckle down and do what it takes to prepare for college. How can you keep that enthusiasm? By succeeding! But that is easier said than done. The old adage that “success breeds success” is true for school; if you start strong and keep the momentum going you will start to see the payoff as the year progresses. Nobody likes to be in too deep, or so far gone that an A is not possible. Once you find yourself in that position, negativity takes over and you stop trying. If you start strong and each day and remind yourself “I still have an A” it’s easier to keep going and working hard – It is a much better strategy to try to MAINTAIN a good grade then to try and resurrect you grade!

Start Strong

Start the year off right; get homework done, get all your supplies early, study. Getting off to a good start is the best way to maintain a good grade. Start with enthusiasm and remind yourself each week that you have a goal and the goal is to succeed.

Be Involved

During you first week of school get involved in your classes. If you are in science class try to pick your own lab group – a group that will share the work and where each member has the same goal as you – To Get an A!

Continuous Effort

Put some time in every day. Remember your goals and do something to move you toward your goals each day. Study, get a jump on assignments and make sure you know what is due. One of the best ways that I know of to increase your understanding of the learning material is to COPY YOUR NOTES. My students always seem to laugh at this notion, but the simple act of copying your notes over, neatly, is a great way to reinforce the material. You not only relearn the information, but you have produced a neat and clear copy for future reference.

If it sounds like these three ideas are also ways to succeed in life or in your first job, you’re right! These are time-tested skills that anyone can learn and that anyone can apply to school, home or work.

Now, Go Out and Be A Success!

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Why I Love Science…

The antifungal powers of cockroach poop.

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Trees and Winter Storms

This winter has brought us a lot of snow and ice. Trees that are native (or acclimated) to our area are well prepared for the cold temperatures and even a modest amount of snow. But this winter has been especially challenging for all trees. How do different trees handle the harsh winter weather? Here is a great article from Michigan State University – Heavy ice accumulation caused widespread damage, but not all trees were affected the same. Take some time to read this. If you have any questions or you need an Arborist, please contact me by email  – Bob Andreucci



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Lessons From a Tree

As we wait for some more snow, I thought I would  share some traits of  TREES that can help them survive on harsh, cold days. These same traits can also help humans survive – both mentally and physically. These are some good “life lessons” –  What lessons can we learn from a tree?

Stand Tall and Proud

Go Out on a Limb

Remember your roots

Drink Plenty of Water

Be Content with your Natural Beauty

Anyone want to expand, or add their own ?

I saw this post on the internet one day and instantly loved it. I forget where I got it – if anyone knows, please share.

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