Dr. Justin Whitehill: Christmas tree farming
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Nearly 100 million households display a Christmas tree, according to industry research.
On Wednesday, December 11, 2024, SciLine interviewed: Dr. Justin Whitehill, an assistant professor and lead of the Christmas Tree Genetics Program at the North Carolina State University. See the footage and transcript from the interview below, or select ‘Contents’ on the left to skip to specific questions.
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Introduction
[0:00:19]
JUSTIN WHITEHILL: My name is Justin Whitehill. I’m an assistant professor here at North Carolina State University in the Department of Forestry and Environmental Resources and the College of Natural Resources. My lab is the Christmas tree genetics program here at NC State, and we use various genetic and genomic principles to help advance and stabilize the North Carolina and the United States Christmas tree industry.
Interview with SciLine
Why do Fraser firs make good Christmas trees?
[0:00:51]
JUSTIN WHITEHILL: What makes those trees so desirable as a real Christmas tree? There are several things. Probably the first and foremost is that the needles are pleasant when you touch them—they’re not prickly. They’re not going to stab you. But they also have really unique, aromatic profiles—really, profiles of the trees remind a lot of people of the holiday season. In North Carolina, our most popular tree and most popular Christmas tree in the United States, is the Fraser fir. And Fraser fir in particular is really known as having the best post-harvest needle retention. So, when that tree is harvested and brought into your living room, the major reason that most people don’t like to buy real trees is because of the messiness issue, and so Fraser fir, just naturally, is really good at holding on to its needles post-harvest. And then the work that we’re doing in our genetics program is improving upon what is already a really good trait. So, I think those are some of the best traits that consumers are really interested in when it comes to Fraser fir.
Can you tell us about your work to improve Fraser fir Christmas trees?
[0:02:01]
JUSTIN WHITEHILL: Our program—we’re sort of a multifaceted program. Everything we do is really centered around genetics and genomics research. Genomics—for those of us that aren’t familiar with that term—just refers to more the DNA of the tree. So, the genome is really what makes or the blueprint of an organism, and so our lab focuses on trying to read that blueprint and then interpret it within the context of various scenarios. And so, we use both the quantitative genetics or traditional breeding approaches to develop new germplasm for the Christmas tree industry, primarily focusing on the Fraser fir, but we also work on some Mediterranean fir species such as Turkish and Trojan fir that also have unique traits that are important to farmers and growers. But we also use, as I mentioned, genomic approaches, and so that means we’re sequencing the genome or understanding the complete set of genes that Fraser fir has in its genome. And so, the genome of Fraser Fir is much larger than most people imagine. So, it’s about five and a half times larger than the human genome. It contains about 16 billion base pairs—or 16 giga base pairs—in its genome. And there’s a lot of confounding and confusing things about conifer genomes, unfortunately. There’s a high level of repeats, which means that when we try to take it apart and put it back together, it’s really hard to know what parts of the genome go next to each other. So there’s a lot of challenges in studying the genomes of conifers in general, but we’re still using these approaches and to try to understand what genes and traits that Fraser fir has that not only allowed to be a great Christmas tree, like what are the genes that contribute to aroma, but we’re also studying some of the challenges that they face, such as climate change, which is, of course, one of the cascading problems we’re facing around the world. But also, with climate change comes other problems, such as pests and diseases. And so, we’re looking at how these organisms interact—pests and diseases interact with the Fraser fir—looking at the molecular relationship with those organisms and trying to develop new and novel approaches to sort of mitigate any threats that may be impacting the Fraser fir. And ultimately, we do all this to try to help the growers and consumers in the long run.
How important is a Christmas tree’s aroma to consumers, and what is responsible for that unique scent?
[0:04:36]
JUSTIN WHITEHILL: The aroma of the real Christmas trees has been cited—there was a survey done by the real Christmas tree board, which is sort of the national commodity board, run under the USDA, United States Department of Agriculture, and they’re sort of responsible for marketing and also support some research efforts. But they did a survey back in 2022 asking consumers what they thought was the best thing about buying a real tree. And overwhelmingly, the response to that question was the aroma. So, it was sort of recognized that the aroma of a real Christmas tree is what draws consumers in. And so, what causes that aroma is a really, kind of fascinating question. It’s one of the questions that sort of got me into conifer research and biology, and when we had a real Christmas tree, when I was younger, had this very citrusy kind of bright aroma. And I’ve often wondered, when I was younger, you know, what’s caused that? Why such a unique aroma profile? And so that sort of led me down a path and to where we are today, working with the Fraser fir. But other conifers, and conifers in general, have this very kind of sticky sap that most people call it. That sap, we call it resin in scientific jargon, but the sap itself is really the source of that aroma, and that sap occurs in multiple locations in the tree and special structures that occur in the bark and the needles.
How does climate change impact Christmas tree farming?
[0:06:09]
JUSTIN WHITEHILL: Trees and conifers around the United States and around the world are really facing this struggle of being not adapted to current or even future climates, and so we’re really at the point right now where we’re working—most of the trees that we grow are dealing with—we’re just starting to see some of these early effects happening. In North Carolina, it’s no real direct effect from the climate. It’s the indirect effect that we see of the climate. So, the warmer, slightly warmer temperatures, slightly less rain, results in more stress on the trees. And because of that, less stress that we’re seeing on the trees, or more stress we’re seeing on the trees, we’re also seeing more favorability going to the proliferation of diseases and insects. And so, these two things kind of come together, and when they come together, you basically get trees that are going to be more stressed. And so, we’re seeing a little bit of that with the Christmas tree industry, but we see that across the landscape with all types of conifers in the forestry sector.
How has the flooding from Hurricane Helene’s landfall in North Carolina affected the national tree supply?
[0:07:15]
JUSTIN WHITEHILL: The flood was a huge impact, not as much on the Christmas tree crop. I would say the crop itself was large, by and large, well preserved. That’s because those trees are typically grown on the sides of mountains, very high up in elevation, from what most of us are thinking about, typically above 3000 feet in elevation. And so, and most of those trees are not grown near a water source and so. But the farmers that are growing those trees will have their homes located near those water sources; their primary nursery production are in that area, and also a lot of their equipment and things. So, a lot of our growers and farmers in North Carolina were impacted more individually, while the crop, by and large, survived. Infrastructure was impacted. But by and large, where Christmas trees are grown, that infrastructure has been repaired, and so we don’t expect really big impacts to the availability of Fraser firs from North Carolina this year. There’s pretty much—the industry has gotten used to having 10 to 20% of the crop somehow be impacted by some extreme weather event. Last year, in 2023, there was a very warm period through the month of November, and a lot of drought that occurred in North Carolina at that time, and that caused unique issues as well for the crop. So we’re sort of getting used to this being the new normal. Unfortunately, we hope that Helene is not something that happens again, but I think our community and our growers really recovered well in such a terrible situation.
Do you have any tips for selecting a Christmas tree?
[0:08:54]
JUSTIN WHITEHILL: When it comes to trees, and specifically, I mean, I guess you have to think about what it is you’re interested in. Do you want that unique aroma profile? Are you bothered by very, you know, strong scents? Do you want something more subtle. And messiness—if that’s a concern—I think Fraser fir is the way to go. If you want a unique aroma profile there’s lots of different trees out there, but for me, I like a nice Fraser fir between the six-to-eight-foot range. I like the aroma of the Fraser fir. It has strong branches. And also, when you’re purchasing a tree, you want a tree that has some weight to it. You don’t want a tree that’s very light and dry. That tree is probably doesn’t have much water left in it, and so that lack of water is going to be stressed out and might have a hard time drinking water when you bring it into your house. So, a freshly cut tree is always the best recommendation we can make. And once you have that tree in your house, just give it as much fresh water as you can. It’ll drink a liter or two in those first couple of days of being brought inside. And then that’ll so kind of slow down as time goes on.
How should Christmas tress be disposed of?
[0:10:05]
JUSTIN WHITEHILL: If you’re going to have a real tree, I encourage everyone to recycle that real tree. It’s a natural product. It’s biodegradable. Most counties will take that tree and recycle it and use it as mulch for parks and other things. And so, it’s a really great, great way to support the environment, I think, by purchasing a real tree.
Do you have any advice for reporters covering this topic?
[Posted December 11, 2024 | Download video]
