Fall brings cooler weather and a change of colors in the tree canopy. While the most obvious are deciduous trees dropping needles (leaves), evergreens will do the same just in a different manner. The effects have been more vivid this year, and property owners have been nervous.
Conifers, including pine, spruce, and arborvitae, will drop needles on an annual basis. It isn’t as noticeable every year unless you are watching closely.
In most cases, it takes about a week or so from start to finish. Secondly, it is the inner needles which are the oldest that turn color and drop. This year’s display seemed to be more evident resulting in the raised concerns.
There are a few factors which can contribute to what seems to be a more visible needle drop cycle. Drought or other environmental stressors can certainly lead to more evident needle yellowing.
Conversely, robust growth over the last two to three years can also be attributable to larger amounts of needles yellowing and dropping.
Different species will hold their needles longer. For instance, white pine holds needles for two to three years, Austrian pines for three years, and most spruces for up to five years or more. That being said, most years one will notice some needle drop off evergreens if they paid close attention. Arborvitae will also show browned inner leaves during this time. This year seemed to be more alarming throughout several areas.
This is not to be confused with deciduous conifers. Three species come to mind, common baldcypress (Taxodium distichum), European larch (Larix decidua), and dawn redwood (Metasequoia glyptostroboides), which will uniformly change color and drop all of their needles. These trees can sometimes suffer an ill-fated early removal by new property owners that do not understand their life cycle and subsequently remove what they thought had died.
There are a couple of key distinguishing factors when observing annual needle drop. As mentioned earlier, only the innermost, older needles will turn color and fall. Typically, this happens in a fairly uniform pattern.
If you notice random branch tips turning yellow or brown, that is not consistent with fall needle drop. These situations call for further observation as they are likely attributed to an insect, disease, nutrient deficiency, or some other environmental factor. In this case, feel free to send pictures for diagnosis and subsequent treatment options.
The take home message is that even if we see some needle discoloration, it may not be a problem. Be prepared with all of the potential symptoms that you may encounter and diagnose carefully. As always, let us know if we can help.