Natural Leaf Drop of Evergreens

Plant name(s): Spruce, pine, fir, cedar, juniper

Symptoms / Characteristics:
Deciduous trees are characterized by the loss of the whole population of leaves every autumn. One common misconception is that evergreen trees and shrubs like spruces, pines and cedars do not drop their leaves. However, the leaves of these trees and shrubs have a definite life span, depending on the species and the environmental conditions. In general the concept is that each year new leaves are added and the oldest ones are shed. The needle leaves of spruces may last for 6 or more years, and therefore, there are leaves of several different ages on the tree. The old leaves of spruces are shed all year but mostly in the spring. The leaves of pines and cedars are actually shed as part of whole shoots. Needle leaves of Scots pine may last 2 or 3 years while some species of pine may have needles up to 5 or more years old. The oldest leaves turn yellow brown and are usually shed in the fall, making the tree look like something may be wrong with it. Whole shoots of cedar also turn brown and are mostly shed in the fall.

One of the problems with natural leaf drop is that it may be confused with symptoms of other problems such as disease, insect infestation or environmental stress. One clue used to determine if the leaf fall is natural or not is the location of the affected leaves. Because the oldest leaves are the ones to be shed, they are located towards the inside of the crown. If it is natural drop, the newest needles and shoots typically remain green and healthy. New growth is located on the outer ends of branches. However, certain diseases, such as needle cast of spruces, may show a similar pattern of leaf discoloration and drop, so it is important to investigate carefully for signs of other problems.


Control / Preventions:
If the tree is under stress, it may shed more leaves than it produces in a given year and the crown becomes thin. In this case, it is wise to provide sufficient water and fertilizer to reduce the stress and reduce premature leaf drop. Otherwise, because the leaf drop is natural, there is nothing to do except maybe dispose of the dropped shoots. It has been shown that when this material builds up under the trees, it may harbor carpenter ants which can invade the home.


Natural Leaf Drop Cedar

 


Natural Leaf Drop Pine