Across North America, warmer temperatures and increased rainfall are affecting Christmas tree plantations. Can growers and researchers save these iconic holiday centerpieces for future generations?
Photography courtesy of the Real Christmas Tree Board
In late June 2021, a massive heat dome stretched from Northern California into British Columbia. For days, temperatures barely fell below 100 degrees Fahrenheit.
“We lost 10 percent of our saleable Christmas trees that year,” says Leanna Anderson, owner of Aldor Acres Family Farm in Langley, British Columbia and treasurer of the BC Christmas Tree Association. “The needles burnt from the heat, and we had to trim them back.”
Photo courtesy of Aldor Acres Farm.
Across North America, heat waves and average increases in temperatures are affecting Christmas tree growers. Without a significant reduction in greenhouse gas emissions, average temperatures in Oregon, the largest producer of Christmas trees in the United States, will increase 8.2 degrees Fahrenheit by 2080. Warmer and drier conditions could alter the composition of Oregon’s forests and reduce productivity of evergreen species such as the Douglas fir, a popular Christmas tree choice.
But increasingly longer and hotter summers are already having a detrimental effect on Christmas trees. Evolved to go into dormancy as temperatures drop in the autumn, conifers develop a resin coating that keeps the needles intact and protects them from frost damage. But with longer summers, the trees are harvested while temperatures in November often remain above freezing. Thus, they aren’t getting that cold signal to develop their resin coat, which causes post-harvest needle loss—that pile of shedding needles under the decorated tree.
Dr. Gary Chastagner, a professor of plant pathology at Washington State University, has been studying Christmas trees for more than 40 years. His research has taken him to Turkey and the Republic of Georgia, where evergreen trees such as the Nordmann fir thrive in the area’s milder climate. Trials, which Chastagner has conducted, have shown that Eurasian trees can last up to three months in water as a cut tree and still retain its needles.
He predicts that, in the future, trees that thrive in these warmer regions will become popular consumer choices. “By identifying trees that don’t need cold acclimation for good needle retention, it will help mitigate problems of post-harvest needle retention, especially if we have warm falls,” he says.
Photography courtesy of Aldor Acres Farm.
Heat, though, is not the only issue affecting the beloved Christmas tree.
Climate expertspredict that, as the atmosphere continues to warm, its ability to hold moisture will increase. This will cause periods of heavier rain and waterlogged soil. For Christmas tree growers, this means phytophthora root rot, a species of spore-like fungal organisms that can lay dormant in soil or plant debris for years. During wet periods, the swimming spores germinate and become attracted to tree roots. Over time, they deprive the host of nutrients and water. Spread by rain, runoff water or even on footwear or farm equipment, once phytophthora is active in the soil, it’s almost impossible to eradicate.
At North Carolina State University, Justin Whitehall, an extension specialist in Christmas tree genetics, notes that there’s been a slow but steady increase in phytophthora in North Carolina. “Eleven percent of fields were infected in 2014. In the last few years, that number is closer to 16 and 17 percent,” he says. This is concerning for a state ranked as thesecond largest producer of Christmas trees in the US.
“Growers and consumers want high-quality trees, but in some places, North American trees cannot be grown because of phytophthora,” says Chastagner. “Eurasian firs, particularly the Nordmann, Trojan and Turkey firs, have shown some resistance to the disease.” Cones from mother trees have been brought back to Washington State, where seeds have been extracted and orchards planted to gauge the trees’ adaptability to the Pacific Northwest.
The Momi fir from Japan has also proven to be resistant to phytophthora. “By working on a biochemical level trying to explore how the species resists the disease, we may be able, through genome editing or modification, get some of those traits into North American Christmas trees,” says Whitehall.
Photography courtesy of Real Christmas Tree Board.
While researchers look at ways to adapt to an altering climate, growers are already making changes.
“When you have a crop that takes between eight and 10 years to grow from seed to harvest, a lot can happen in that window,” says Marsha Gray, executive director of the Real Christmas Tree Board (RCTB), a non-profit organization supporting Christmas tree growers throughout North America. “When we are talking about weather issues, especially when it comes to getting seedlings established, growers are having a harder time,” she says. But they’re adapting.
In the United States, there are 15,000 farms growing Christmas trees and more than 100,000 people are employed annually by growers and sellers. In an industry valued at more than $2.5 billion, approximately 25 million to 30 million natural Christmas trees are sold annually. With so much at stake, growers have no choice but to adhere to changing conditions.
In North Carolina, planting on slopes encourages better water drainage and helps combat phytophthora. In other places, such as Oregon, growers are looking at adding irrigation. Although common in other regions, the soil in the state has traditionally held enough moisture to keep trees from drying out. At Aldor Acres in British Columbia, Anderson touts irrigation as having been the farm’s saving grace during hotter summers. “It’s a fine line, though, between keeping the tree moist when it’s hot but not too wet that it encourages disease.”
The RCTB has invested more than $250,000 in research to try and ensure the future is merry and bright for the trees. “That might seem like a lot,” says Gray, “but, for our industry, that’s more than has ever been invested. Over half of our research is in response to the changing weather.”
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