Every fall, people look forward to Mother Nature sharing her palette of reds, yellows, purples, browns, oranges and golds as deciduous tree leaves change color and drop in preparation for winter. We understand and expect the leaves on our maple, oak and elm trees to turn color and fall off. What many people are unaware of though is that most conifers also drop their needles at this time. Fall needle drop in conifers is no different than leaf drop in deciduous trees. The change in color and drop are a physiological response to the shorter days and cooler nights as trees prepare for winter.
Evergreen conifers such as pines, spruce, fir and arborvitae shed their oldest needles each year starting in late August and continuing into October. Their oldest, interior needles turn yellow while needles at the tips of the branches stay green. This yellowing and dropping of the interior needles occurs uniformly from the top to the bottom of the tree. When and how dramatic this event is varies with tree species, summer weather conditions and individual tree health.
Normal fall needle yellowing on Eastern white pine.
Photo credit: Steven Katovich, Bugwood.com.
Tamarack, larch and bald cypress are less familiar trees found throughout Michigan. While these trees are also conifers, they differ from the pine, spruce and fir in that they lose all their needles each fall.
This, too, is a natural phenomenon, but causes alarm to people unfamiliar with these deciduous conifers. Like other deciduous trees such as maples and oaks, these trees will grow all new foliage next spring.
Normal fall needle coloration on Larch tree prior to
shedding all its needles. Photo credit: Rebecca Finneran, MSUE.
While many people fear their conifer trees are dying when they notice yellowing and dropping needles in the fall, rest assured this is normal and tree health is not impacted. Bear in mind though that needle loss at other times of the year, or at the tips of the branches, is not normal for these species and may be due to an insect or fungal pest or the result of severe environmental stress.
This article originally published on October 21, 2011:
Mary Wilson, Michigan State University Extension
For more information from MSU Extension, visit news.msue.msu.edu.
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