This fall some of the needles on my white pines have turned yellow and begun dropping to the ground. Is this a problem?

FAQ
Question: 

This fall some of the needles on my white pines have turned yellow and begun dropping to the ground. Is this a problem?

Answer: 

The loss of needles is probably due to seasonal needle drop. Deciduous trees, such as maple and ash, drop all of their leaves in fall. Though it largely goes unnoticed, evergreens also lose a portion of their foliage (needles) on a yearly basis. Seasonal needle drop on most evergreens occurs in fall. Needle loss is most noticeable on white pines. As much as one-half of the needles on white pines may drop in early fall. Seasonal needle loss is less noticeable on spruces, firs, and other pines as they retain a higher percentage of their needles. Seasonal needle drop is uniformly distributed throughout the inner part of the evergreen. It is the oldest needles which are shed. The needles turn uniformly yellow or brown and drop to the ground.