Evergreen shrubs turn brown for a variety of environmental reasons, including winter burn, herbicide and animal damage. In order to determine the severity of the damage, it is important to examine the roots, branches and trunk of the shrub or tree.
When the ground is frozen, an evergreen is unable to recover from its roots the moisture it loses through its needles. Exposure to de-icing salts also dries the roots, and improper or careless herbicide application can damage foliage. Animal urine and the consumption of the foliage and bark by rabbits, porcupines or birds may also cause the evergreen to turn brown. Other sources of damage include air pollution, drought, lack of nutrients such as iron and incorrect pruning.