Pests AND environmental PROBLEMS of High Altitude Landscapes

Jessica Hendryx B.S. in Horticulture Science with a Landscape Design Option ~ Montana State University, Bozeman

Winter Desiccation of Evergreen Trees

Desiccation is the drying out of plant tissues. This occurs in plants when transpiration exceeds moisture absorption, which then results in wilting and damage to the plant tissues. Winter desiccation is very common on the evergreen trees in the higher altitudes. A typical winter day includes below freezing temperatures and heavy winds. This causes a problem to the plants that did not obtain enough water before the ground froze, especially evergreen trees. Evergreens, because their leaves remain attached through the winter, transpire at a rate faster than those without leaves. This leaves them more susceptible to desiccation, especially the long needle pines. The less susceptible evergreens are those with shorter needles, such as a spruce.

Some of the symptoms include tip or entire leaf burn. The top is most likely to dry out first for two reasons. It is the farthest away from the roots therefore it receives water last and it is also more likely to be the most exposed from snow cover. Snow provides insulation from the wind which can quickly dry out a plant. A common symptom is to see a visible line where the top half of the tree was burned while the bottom half where the tree was insulated by snow cover remains healthy. Severe damage can be done to a tree lacking in water and if left unattended it will die.  

There are a variety of preventative measures. The most important is water, but the timing of this is crucial. If a plant is watered heavily in the late summer the plant is likely to send out new growth and will not be ready to harden off for the winter. A plant that does not harden off is susceptible to a variety of problems. Water the plant sparingly in the fall before the deciduous tree leaves fall. After the deciduous leaves have fallen begin heavy watering once a week until the ground freezes. Until the ground thaws again there is not much that can be done. Another way to prevent desiccation is to place evergreen trees out of sunny windy areas.

Be aware of the plants and where they are being planted. Take the precautions necessary to keep the plants healthy, especially on newly transplanted trees. In a current years landscape, the first years needles may be lost to desiccation. However, the plant will most likely survive, but avoid a second year of desiccation by proper watering techniques.

On a side note make sure to clean up any excessive needle drop which could end up being a fire hazard.

Check out this web site for more information:   http://gardenguide.montana.edu/priorfebs/febru97.html

 

 

Pine tree tip burn

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Reference:

Harris, R.W. Clark, J.R. Matheny, N.P. Arboriculture. Prentice Hall:1999 pgs 354--355, 559

Montana State University Extension Service 
Designed and researched by Jessica Hendryx - B.S. in Horticulture with a Landscape Design Option
For problems or questions regarding this web contact [martha@montana.edu].
Last updated: April 24, 2002.