Fall needle drop... should you be concerned?

Fall is here and Hamilton County landscapes are colorfully painted with a variety of fall colors as the plants naturally begin shedding their leaves as winter rushes in. This time of the year, my phone rings frequently with calls from concerned homeowners worried about evergreens yellowing and dropping an abundance of needles. I always ask one very important question to help the caller determine the cause of the needle drop.

Where are the affected needles located? If normal fall needle drop is the cause for concern, then needles will be turning yellow on the inside of the tree, and the needles farthest out on the branches remain green. Natural needle drop is a normal process and does not harm the health of the tree.

All trees species will drop leaves or needles at one time or another. Evergreen needles have varying life spans, depending on the species. White pine needles live for 2 years while other pines have needles that persist 2-6 years, depending on species. Spruce needles live 3-10 years. Some species of evergreens have a more noticeable leaf drop than others, shedding many needles all at once, while others shed a little at a time such that it is hardly noticed. White pine and arborvitae have very dramatic annual shed which can be quite alarming if you don't realize that it's perfectly normal.

I would like to mention that the last few months have been very dry in our county, drought may increase needle drop but this, in itself, does not harm the tree. On years where we experience high stress and temperature extremes, evergreens can decline and reach an eventual death.  For more information see this publication about drought stressed plants.

Excerpts taken from the following online publication:
Normal Needle Drop: Even Healthy Evergreens are NOT Evergreen
Gail Ruhl, Sr. Plant Disease Diagnostician and Rosie Lerner, Consumer Horticulture Extension Specialist

Purdue Univeristy