MSU scientists cast light on Christmas tree research

Contact: Meg Henderson

STARKVILLE, Miss.—From the Griswolds to the Grinch, just about every holiday movie features characters cutting, decorating or stealing the perfect Christmas tree. But most people—including moviegoers—don’t consider that Christmas trees take work to cultivate. Like all trees, they are subject to the threats of disease, insects, fungi and other menaces. This is why scientists in Mississippi State’s Forest and Wildlife Research Center have been studying some of the most popular tree species that decorate homes for the holidays.

Forestry Associate Professor Joshua Granger explained why Christmas trees often get overlooked in forestry programs.

“Christmas trees are considered a gray area in the forestry industry. Is it horticulture? Is it landscaping? Or is it forestry?” Granger said. “When I came to MSU, we didn’t have any research with these trees, but I’ve begun working with the Southern Christmas Tree Association to develop some studies to help our growers out.”

Last year, Granger began research on behalf of a partnership established between MSU and Shady Pond Tree Farm in St. Tammany Parish, Louisiana. Former owner Clark Gernon had discovered a novel variety of Leyland cypress, a popular, fast-growing species, on his farm. The single tree was unique in its apparent resistance to Passalora sequoia—a fast-spreading foliar pathogen attacking his other trees.

“This pathogen attacks the foliage either top-down, bottom-up or inside-out until it all turns brown and dies,” he said. “Because the American market likes a cone-shaped, dense tree, farmers have to shear the trees so they grow denser, and that actually helps the pathogen do more damage.”

With his colleague, Assistant Professor Ashley Schulz, and forestry undergraduates, Granger has been rooting plant material from the christened Leighton Green Gernon trees in the department’s greenhouse facility. The trees will be established in the greenhouse for a year and then transplanted outdoors, where they will be grown and propagated for their lifetime.

“It was Mr. Gernon’s dream to have researchers study the tree, trial it and qualify it as a unique cultivar, or species. He passed away last Christmas Eve, but we are carrying out his wish through our work on campus,” he said.

In a separate project, Granger is exploring other species for their potential as Christmas trees.

“Leyland cypress trees are planted across Mississippi and much of the South as an ornamental, in addition to their cultivation for Christmas tree farms,” he said. “The Leighton Green Gernon trees grow well, but their needles have a white-blue tone, which might be a more niche market. Most people want a dark-green tree.”

The first part of this long-term project is to put the trees through the same process commercial growers are using: establishing the trees in a nursery setting, where they can be grown to about 6 feet in height and sheared and sculpted into the desirable cone shape. Species in the study include spruce pine, Atlantic white cedar, Arizona cypress and Leyland cypress hybrids. Once the trees are grown, Granger and his team will gauge consumer preference for the different species and conduct in-home tests to see how they fare indoors for a month or more.

Granger also is beginning a new collaboration with Joby Czarnecki, an associate research professor in MSU’s Department of Plant and Soil Sciences and the Geosystems Research Institute, deploying scanning technology into Leyland cypress stands to identify early stages of Passalora sequoia.

“Right now, growers are using a standard spraying protocol, regardless of whether the tree needs it or not,” he said. “If we can identify the extent of the damage, we can provide better guidelines that will save growers time and money.”

At MSU’s Hiram D. Palmertree North Mississippi Research and Extension Center in Verona, scientists have just completed a three-year tree study requested by the SCTA and supported by a specialty crop block grant from the Mississippi Department of Agriculture and Commerce. Jeff Wilson, an associate professor of ornamental horticulture with the MSU Extension Service, investigated different nitrogen rate applications to three tree species commonly grown on Southern Christmas tree farms.

“Before Dr. Granger and I started this work, there had not been any research on Christmas trees in Mississippi since the late ’70s or early ’80s, but there is a real need for the research today,” he said. “We have growers who have sold Christmas trees for 50 years, and although the farming population is aging, we’re also seeing younger people start up new farms as a side business, selling trees and branching out into agritourism.”

The work will end this winter as Wilson and his crew harvest and sell the trees, but he hopes more research will follow.

“This was just one small nitrogen study, but there’s a long list of different studies we could do that would benefit growers across the state, helping them manage their trees more efficiently and increase their profits,” he said.

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