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Why Do Leaves Change Colors?

People in the United States are generally unaware how lucky they are to see the brilliance of the leaves changing colors each fall.  The driving force behind fall color is the seasons themselves.  The gradual change of daytime and nighttime temperatures in the fall triggers a very important physiological process in trees that, often occurs without understanding.  The change in temperatures associated with our temperate climate, triggers the process of leaf senescence.  Leaf senescence, or the shedding of leaves, is the culmination of several interrelated processes. 

During the season leaves work hard to produce proteins and starches.  These molecules represent a large investment of the trees efforts, and in an attempt to conserve its own resources, trees will break these materials down into smaller molecules and transport them to the stem and roots for storage and use later when the temperatures once again rise.   

Everyone knows the green pigment known as chlorophyll, is responsible for capturing light from the sun and converting it into energy for the tree.  Less known, is the fact that chlorophyll is constantly breaking down and being replaced by the chloroplasts within cell membranes.  The fall weather signals the trees that it is okay to stop using energy to replace the chlorophyll.  As the accumulated chlorophyll decreases, others pigments known as carotenoids(orange), and anthocyanins(red, purple) are exposed.  These pigments are always present, and work in conjunction chlorophyll to produce compounds such as antioxidants that are commonly associated with fruits and vegetables. 

The internal process that is the most vital in the fall is the “dehydrating “of the plants cellular tissues.  Moisture inside and in between cells has to be regulated in order to prevent from freezing.  If moisture freezes inside cells it forms crystals that will puncture cell walls.  Once the cell walls are injured the cell will die and the tree will lose its ability to be active in the spring.  Protecting the cells must be completed in order to keep woody plant tissue alive.  The dehydrating process in trees is known as “Hardening Off”. 

This is an abbreviated description of leaf color development in trees.  Various hormones regulate the underlying processes.  I won’t go into this subject any further because I have sometimes been accused of explaining things to death.

Colorado is not lucky enough to have brilliant fall color that is evidenced in places such as Connecticut, Virginia, and the thriving metropolis of Hanover, Pennsylvania.  I have been fortunate enough to see the seasons change in places all over this country, and I strongly recommend a fall drive through Smoky Mountains to cleanse your soul and recharge your inner battery.


Fall Needle Cast

Almost as sure as the seasons themselves, we begin to receive an influx of calls this time of year from clients expressing dire concern about their needle-bearing trees.  The notes that come across my desk often include, “is there something wrong with the Pine trees”, “my tree has that notorious Pine Beetle”, and “my tree is dying, come right away!”  The answer is there is nothing wrong with your tree, it’s not the beetle, and it’s not dying.  What we are seeing throughout the spruce, pines, and firs all over Colorado is a natural process of shedding the older, less efficient leaf tissue. 

Each tree has a slightly different schedule for conducting the physiological processes that are responsible for the eventual dropping of the needles.  The major difference between normal needle drop and a stress induced action is the portion of the tree that is shed.  The tree should shed needle tissue produced in the same year, and it should not affect any of the other year’s growth.  The dropping needles should be clean from small fruiting structures or discolored banding that would indicate the presence of a fungal pathogen. 

If you are unsure of what is happening to your trees, please don’t hesitate to call us at Mt. High.  Tree disorders are easier to treat during the initial stages of symptoms, so early diagnosis is the key to any potential recovery.


Mt. Pine Beetle Update

The 2008 season has shown exactly what many people feared.  The migration of Mt. Pine Beetle has reached the Front Range.  Scotch Pines have been attacked from Lakewood to Fort Collins.  Large populations resulting in 5-10 dead trees per acre have been found on Flagstaff Mountain in Boulder.  Even larger populations have been found 8 miles west of Highways 72 and 93 in Coal Creek Canyon.  The dry summer we experienced this year will no doubt increase the stress and subsequent likelihood of an attack.  I don’t, by any means, want to come across as an alarmist, but it is very important to closely monitor your property.  The sooner you identify a problem in your area, the sooner a plan for protection can be implemented.

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Mt. High Tree has been participating in research to develop new environmentally safer ways to combat this beetle.  The new method is injected directly into the basal flare of the tree, thus eliminating the environmental impacts of aerial spraying.  The risk of poisoning wildlife as well as the chance of contaminating water supplies is eliminated.  All the material is placed directly into the tree where it can act as a shield against the bombarding pest.  Early test results have been promising, and EPA approval is pending. 


Water Your Trees This Winter

I understand that the past several weeks have been practically perfect outside.  Warm days, cool nights, plenty of sunshine, and even a little rain here and there.  The truth remains that we are dramatically behind the mark when it comes to the rainfall needed to sustain the plant material in our landscapes.  As winter approaches plants need moisture to conduct the processes of preparing for the cold days to come.  When Mother Nature fails to come through with the rainfall we must pick up the slack.  Please pay attention to the outside conditions and irrigate your trees as needed.  If you need any help in developing a plan let us know.  If watering is something you would rather not bother yourself with then let us help with our Deep Root Watering services.  The addition of yuccah plant extract and biological components will further increase the health of your soils.  We are here to help.


Time To Tuck In Your Turf

We have all seen commercials from popular turf companies promoting winterizing your lawn.  The idea of preparing your lawn for fall is more complicated than just tossing some fertilizer on the grass.  The goal of “winterizing” your lawn is to put nutrients in place that will remain unavailable until soil temperatures increase in the spring.  As the turf roots become active in spring the nutrients they need will be in place and be available for absorption.  Coatings are applied to fertilizers in order to accomplish the timed release of nutrients in the spring so it is important to choose the right fertilizer. 

Additionally, many weeds can still be treated in fall in order to decrease the seeds that will eventually germinate in the spring.