Needle Casting of Evergreens
What is needle casting?
Needle casting is normal for evergreen trees and shrubs, even though most people think it is a disease and/or an insect. All evergreen needles eventually die. The older needles are on the inside and usually die over an entire growing season and, therefore, are not noticed. Occasionally, they all die, turn yellow to brown together. This aging process is normal and is not an infectious disease.
Why do my evergreens cast their needles?
Evergreens cast their needles to make room for the new needles which will emerge in the following year, also due to sunlight being able to reach the needles on the outer portion of the stems. Therefore the needles on the inner portion of the stem are unneeded due to lack of sunlight and are cast.
Can I do anything to prevent my evergreens from casting their needles?
No, there is nothing you can do to prevent the needles from casting; in fact you would do more damage by preventing the evergreens from casting the needles as apposed to allowing it to occur. Needle casting in most instances is normal so by allowing the evergreen tree or shrub to cast its needles will not harm the plant but will help it continue its lifecycle.
I know needle casting is normal but it looks like there are more needles casting then usual is there something else wrong?
There are a variety of reasons why the evergreen tree or shrub is casting more then normal. It could be that evergreen had undergone a severe case of stress over the spring/summer from a drought or too much water and is showing the signs of stress by casting more needles then normal. Other causes could be insect or disease related. Contact a landscape professional for a proper evaluation.
What are the benefits to evergreens casting their needles?
The main benefit is better air circulation within the canopy of the tree or shrub. Another benefit is less energy is being used to keep the remaining needles alive; the needles on the outer stem will collect enough sunlight necessary to survive.