Don’t Panic! Those iconic words from “A Hitchhiker’s Guide to the Galaxy” apply to many homeowners at this time of year. I commonly receive phone calls and e-mails starting in mid-September through mid-October from people worried that their pine trees might be dying. What’s the problem? The needles on their pine trees are turning color and falling off.
Everyone is familiar, and perhaps even look forward to this time of year, when nature’s pageant of color spreads across the landscape. The reds, yellows, purples, browns, oranges, and golds are offset nicely by the dark greens of the spruces, pines and firs. We understand and expect the leaves on our maple, oak and ash trees to turn color and fall off our trees. But for those who have never seen or paid attention to their pine trees they wonder or worry if something isn’t wrong.
I mention pines because these tend to stand out in the landscape, in your yard, and in peoples minds; either because of the beautiful gold color of the interior needles of the white pines or the heavy needle drop and endless raking (at least it seems that way) of the red pine needles.
We commonly refer to these trees as “evergreen” or learn in elementary school that the difference between a conifer and a deciduous trees is that deciduous trees drop their leaves in the fall and conifers don’t. This is partially true. According to “Webster” deciduous means “falling off or shed seasonally or at a certain stage of development in the life cycle. “ While coniferous means “cone bearing.” These terms are not mutually exclusive. Just look at the tamarack.
The needles of the tamarack turn a beautiful golden color at this time of year and lights up, what are often considered dismal, tamarack – black spruce swamps. However, as a yard tree many landowners panic when they see the needles turn color and fall off; and on the tamarack all of the needles fall off. More than once I have stopped a landowner from cutting down a tamarack tree that they thought was dead because the needles fell off.
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 the tree prepares for winter. The actual process is simple; trees “wall off” or separate the leaves or needles from the vascular system of the tree. This process is not immediate, it takes times, but once it is complete the leaves or needles fall off. Given the weather at this time of year, needle drop can be quite spectacular.
What should you expect to see? Tamarack and Bald Cypress (we don’t see many of these in Wisconsin but there are some) are true deciduous conifers. All of their needles fall off each year. However, most conifers only lose their older, interior needles. Pines are perhaps the most striking because of the volume, the fact that they are “self-pruning” (their lower branches do not survive in the shade of their own upper and exterior foliage), and the fact that the needles live only three growing seasons. Think of it this way; the needles that sprouted from buds this spring will drop off in September or October of 2013. Spruce and fir needles last somewhat longer, usually around seven years, however most folks rarely notice needle drop in these trees because the foliage is so dense (seven years worth of growth instead of three), they are more tolerant of shade, and the needles are finer. Frankly, most folks don’t notice because they do not mow underneath their spruce and fir trees but they do mow under their pines.
So… Don’t Panic! Fall needle drop is normal and doesn’t signify anything more than the fact that the days are getting shorter, the nights are growing colder, and you now have additional opportunities for yardwork that you didn’t have before.