Planting Depth

Many current tree problems can be traced back to planting procedures.  Unfortunately, trees are often planted too deep. That is to say the root flare at the base of the trunk is well below grade and the tree looks like a pole coming out of the ground instead of seeing large lateral roots giving rise to the trunk.  This causes trunk tissue to be constantly wet and makes it susceptible to crown rot which leads to root rot.  Trunks don’t like to be constantly wet as roots don’t like to be constantly dry.  Soil borne fungi and other pathogens will infect the root crown and travel down to the roots.  Many soil borne pathogens such Armillaria and Phytophora become a major problem especially with oak trees.  As the large roots become infected they also become soft and the structural integrity of the tree is compromised.

Additionally, roots need to be close to the surface where they can absorb nutrients from organic matter and most importantly oxygen.  Most water and nutrient absorbing roots are located in the top 6” to 18” of soil.  In this soil horizon most of the oxygen and organic matter (from dead decaying plant material etc.) is deposited.  The deeper soil horizons contain carbon dioxide and minerals which are the result of broken up parent material (rocks).  The deeper roots are planted the less oxygen they can absorb, the less oxygen plants absorb the less they can carry out essential metabolic processes necessary for proper growth, in short, the root system suffocates.

Another indication of this is a soft root ball.  The placement of emitters directly against the trunk also contributes to this condition.

European White Birch Betula pendula

 Short Life Span – This short-lived tree only averages 15 to 30 years in theRenoarea.  In their native habitat they average a life span of 50 to 60 years which is still short for a tree.  Northern Nevada’s climate has a lot to do with the health and shortened life span of birch trees.  Birch trees are a riparian species native to wetlands areas and prefer moist soils. Northern Nevadasoils contain only about ½” of top soil (organic matter) compared to birch trees’ native regions where the soil may have several inches or even feet of organic matter.  The pH of our soils is alkali (pH of 7.3 to 8.5) compared to the trees preferred pH of 6.8.  Soil drainage is also an important factor for this tree to thrive.  To help these trees live longer; I prescribe soil fracturing using a probe designed to inject water into the soil.  This can be bought at most hardware stores.  The soil probe will forcibly inject water to the root zone, as it is absorbed it leaves air pockets similar to the conditions of a well drained soil.

Other Problems

• Sapsucker birds cause consideration trunk and vascular damage to birch trees by pecking at the trunk with their beak.  I personally have not tried to control this pest, however I have heard that placing a fake bird of prey somewhere visible to the sapsuckers or putting a rubber snake in the tree seems to scare them off.
• Bronze Birch Borer attacks the vascular cambium of trees preventing the flow of nutrients and water to the leaves as well as carbohydrates (food energy) produced in the leaves to the roots.  Common signs of the insect include: small half circle or ‘D’ shaped exit holes in the bark; top die-back; and swelling under the bark caused by callusing.  To prevent infestation, a preventative pesticide application should be applied in April.

      Written by Brian S. Dean Copyrighted 2001