There are many reasons a tree begins to weaken, wither and potentially dies that have nothing to do with disease. Extreme temperature changes and water supply are the primary cause of tree problems. Secondarily would be chemical substances in the soil, water or air, transplant shock and injury.

So what are the ways a tree can become weakened?

1. Hot or High Temperatures - Hot temperatures can cause trees to defoliate and their leaves to become scorched. Heat or drying winds cause a rapid loss of water. When leaves begin to turn yellow or brown and fall prematurely, it is most likely due to heat.



2. Cold Temperatures - In early fall or late spring, when trees are actively growing, trees are susceptible to extreme cold and frost. Signs of cold weather injury include Frost Crack, where long vertical bulges or cracks are caused in the bark of a tree. Frost cracking can reoccur in the same place causing a buildup of tissues and formations of scarring.  To protect your trees in the winter you can do the following:

•    Plant tree species adapted to local conditions.
•    Cover young trees if frost is expected.
•    Avoid planting in low-lying areas subject to frost.
•    Do not use high nitrogen fertilizer late in the growing season.
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Avoid wounds to the trunk and properly prune branches to prevent the formation of frost cracks.

3. Drought - Drought occurs when there is a lack of rain over a long period of time. Without an adequate storage of water within the ground the tree cannot uptake water by its roots. Symptoms include wilting, off-color foliage, twig and branch dieback in the crown, and the death of fine roots. The crowns of drought stricken trees usually die from the top down and from the outside in. Trees in this condition are more readily attacked by fungi and insects. Shallow-rooted trees, and trees planted on light, sandy soils with poor moisture-holding capacity are most susceptible to drought. To protect your trees from drought:

•    Do not plant shallow-rooted species in areas of low moisture or on sandy soils.
•    Put mulch around the base of the tree. In addition to helping retain soil moisture, mulch helps to control weeds, preventing lawnmower and weed whip injury.
•    Conifers growing over high water tables for long periods may die quickly after the water table drops. The foliage turns red and drops off soon after death.
•    Water ornamental trees about once a week to moisten soil 6 to 12 inches deep into the root zone.

4. Excess Moisture - Trees can get too much water as well as too little. Trees planted in areas where there is poor drainage can become waterlogged. When this happens, oxygen is deprived from the roots and the tree begins to die. Symptoms of oxygen deficiency closely resemble those of drought injury: reduced growth, small leaves and thin crowns, twig and branch dieback, and tree death. Roots in waterlogged soils are susceptible to a variety of soil-borne fungal pathogens. To protect your plants you can:

•    Plant species that are adapted to the conditions in areas subject to periodic flooding.
•    Prepare planting sites to allow for adequate drainage and root growth.

5. Chemical Injury - There are many chemicals in the air and water that effect trees. Symptoms of chemical injury are often difficult to diagnose, as the possibilities are endless. Some include:

a. Nutrient Deficiency

- Trees need certain nutrients for proper growth. Nitrogen, phosphorous, and potassium are the most important. Symptoms of nutrient deficiency mimic many other diseases and vary greatly depending upon which nutrient is lacking. The most common symptoms of nutrient deficiency are: reduced growth, yellowing, and necrosis.

b. Herbicide Injury

- Herbicides applied improperly can injure trees. Leaves of deciduous trees will become distorted, curled, and brown on the margins. Conifer needles will turn yellow or brown, and succulent shoots will curl or become deformed. Trees will usually survive, but their growth will be stunted.

c. Salt Injury - Salts from roads that is splashed onto the foliage or is absorbed through the roots will cause a browning of the tree, especially on the side facing the roadway. Trees growing where salt accumulates because of drainage patterns will also be affected. The affected foliage will fall off in the spring, thinning the crown, although new growth will make the tree appear otherwise healthy. However, these trees will grow more slowly and remain stunted, and may eventually be killed by prolonged exposure.

There are other noninfectious factors that can cause trees to wither or die including winter scald and other types of pollution. Before treating your trees, be sure to examine all the possibilities. Consult a professional to save yourself time and money and in the long run you may help your tree become healthier.