Every year during the first few weeks of November, New Hanover County residents stop by the plant clinic carrying plastic baggies containing brown interior branches of one sort of conifer or another. All of them experiencing the same problem and asking, “What’s causing my plant to die?” Those that don’t bring the actual parts of their trees in often described the symptoms. “My tree was fine last week and suddenly it started turning brown.” Or “The needles are all turning yellow and dropping to the ground.”


Every year during the first few weeks of November, New Hanover County residents stop by the plant clinic carrying plastic baggies containing brown interior branches of one sort of conifer or another.  All of them experiencing the same problem and asking, “What’s causing my plant to die?”  Those that don’t bring the actual parts of their trees in often described the symptoms. “My tree was fine last week and suddenly it started turning brown.”  Or “The needles are all turning yellow and dropping to the ground.”



People enjoy seeing the fall color 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 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.



Evergreens do not hold their needles forever; they just hold them year-round for several years. How long an evergreen holds its foliage depends on the variety. Foliage on a conifer can be in the form of needles, as in pine trees, or it can be broader and more flattened, as is the case with arborvitae or Leyland cypress. 



Deciduous tree, like maples begin their growth cycle in the spring by pushing out new leaves from dormant buds most often found on the tips of branches. The leaves perform photosynthesis all spring, summer and into the fall, converting sunlight into sugars.  Leaves also transpire, meaning they lose water through their pores. As sunlight decreases in the fall and temperatures start to drop, trees begin preparing themselves for winter. They store sugar in the form of sap and shed their leaves, which prevents them from losing moisture over the winter.



Conifers, on the other hand, have a slightly different growth cycle. They, too, begin their growth in the spring by pushing out new needles or “leaves” from dormant buds. They, too, use their green foliage to photosynthesize over the course of the spring, summer and fall, but fall is where conifers differ dramatically from deciduous trees.  Rather than lose the leaves they grew the previous spring, conifers hold onto these leaves for another year and a half. They remain on the tree, staying “green” or, in the case of some conifers  “blue” throughout the winter and through the following growing season.



The following October-November, this older foliage turns yellow and then brown, and then falls off just as the foliage of deciduous trees does. Often it looks as though the tree is dying from the inside, especially on a mature tree, since the interior foliage is what the tree is shedding. 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.



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.



Conifers for the most part need full sun and well-drained soil to thrive. There are a few that can tolerate some shade, but they grow best in full sun.



If they are planted in too much shade, they will have weak growth and will slowly fade away. The same holds true for those planted in wet spots or seasonally wet spots. They usually fail to thrive.



So if you are experiencing browning or yellowing on the interior foliage of your conifers. Don’t worry this is normal for this time of year.



For gardening help visit ces.ncsu.edu, where you can submit questions via the ‘Ask an Expert’ link, or contact us: If you live in Pender County, call 910-259-1238. In New Hanover County, call 910-798-7660. In Brunswick County call 910-253-2610.



 



Susan Brown is the consumer horticulture extension agent with the North Carolina Cooperative Extension in New Hanover County. Contact her at susan_brown@ncsu.edu or 910-798-7476.