Seasonal Needle Loss

Seasonal Needle Loss 

The term "evergreen" used to describe conifer trees isn't exactly accurate. It's normal for some of the needles on evergreens to turn yellow or brown and fall from the tree in autumn. This seasonal needle loss, also called fall needle drop, is a natural occurrence. The oldest (innermost) needles are eventually shed from trees such as pine, spruce, and fir. The discoloration and loss of needles can be alarming to tree owners that are not aware of this normal process. Some fear that a disease is rapidly occurring.

Despite being called "evergreens", conifers do not keep all their needles indefinitely. Older needled turn yellow or brown, die, and are shed regularly. For white pines and arborvitae, all of last year's needles are lost simultaneously in the autumn, causing the trees to appear more brown than usual at this time of year. Scots and Austrian pines retain their needles for three years, so their seasonal needle loss is less noticeable. Other conifers, such as firs and spruces, retain their needles even longer, so even though they lose their oldest needles, the effect is virtually unnoticeable.

The degree of needle loss seen can vary from tree to tree and year to year. Needle drop is often especially noticeable after stressful summers or falls.

Distinguishing Seasonal Needle Loss from Disease

Although it may appear alarming at first, seasonal needle loss is a natural part of the life cycle of the tree. However, browning of the needles at other times of the year may be a sign of disease.  Environmental stresses, such as drought and hot temperatures, may cause greater-than-normal loss of needles. The normal pattern of seasonal needle loss is a gradual discoloration and eventual loss of inner needles from the top to the bottom of the trees. In contrast, fungal diseases often cause browning of the newest (outermost) needles, death of entire branches, or thinning of needles on just the lower branches.

Deciduous Conifers Lose All Their Needles Each Fall

Some needled conifers, such as larch (Larix), bald cypress (Taxodium), and dawn redwood (Metasequoia), are deciduous and lose all their needles each fall. 

All of the needles turn yellow, russet, or orangish to reddish brown and fall from these trees.  This is part of its natural annual life cycle.  Unfortunate events have occurred in the past, where owners or caretakers of such trees removed them after incorrectly concluding that the barren trees were dead!

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if your plant has a disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents.  If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us 

Fungicide applications may be avoided by following good Integrated Pest Management practices like those listed in this encyclopedia article. Often, the only preventative application is effective to manage plant diseases. If the problem requires a fungicide, state law requires the user to read and follow all labels accordingly. For more information, read Proper fungicide use.