CORVALLIS, Ore. — In her photo on the Whitehill Lab Christmas Tree Genetics Program webpage, Priya Rajarapu is wearing a white lab coat while sitting at a bench next to a light microscope.
The photo portrays a researcher who spent 14 years in labs exercising her expertise as an entomologist, biochemist and molecular biologist. But Rajarapu — who left the lab at North Carolina State University last fall to become the new Christmas tree specialist for the Oregon State University Extension Service — doesn’t want to be stereotyped as a scientist who is only interested in lab work.
As Rajarapu explains it, Justin Whitehill, the leader of the Christmas Tree Genetics Program at N.C. State, would take lab members to meetings of the North Carolina Christmas Tree Association so they could meet growers.
Rajarapu cherished those interactions.
“We had a chance to interact with growers, showcase what we were doing, and hear from them first-hand,” Rajarapu said. “It was rewarding to see what I was doing had a meaning and a purpose. When you get to meet Christmas tree growers you get to be creative. I realized that I should have been an Extension specialist from the get-go.”
"When you get to meet Christmas tree growers you get to be creative. I realized that I should have been an Extension specialist from the get-go.”
Oregon is the leading producer of Christmas trees in the United States, supplying over 33% of the national market. In 2023, Oregon produced approximately 3.4 million Christmas trees, generating around $117.6 million in gross sales.
Rajarapu, an assistant professor in the Department of Forest Engineering, Resources & Management in the College of Forestry, is the second Christmas tree specialist in the history of OSU Extension. Chal Landgren held the position from 2008 until his retirement in 2023.
Rajarapu’s official start date at OSU was Dec. 24 — appropriate for someone who studies Christmas trees. In addition to working with growers throughout Western Oregon, Rajarapu oversees the Christmas tree seed orchards established by Landgren at the OSU North Willamette Research and Extension Center (NWREC) in Aurora.
“I don’t want anybody to see me as just good at lab research,” she said. “I’m a very practical person and believe in applied research. This position is the perfect blend of my personal interests in service and research.”
‘Great’ support from growers
Rajarapu has traveled to several Christmas tree farms in her first few months. These trips have allowed her to learn, observe and discuss the issues of producing Christmas trees in Oregon.
“The growers have been great,” she said. “I feel very fortunate that I’ve been accepted into their community. Growers are the experts. I joke that they should have applied for this Extension specialist position. They are willing to teach me and willing to help me. Having that kind of support is very important for a position like this.”
Rajarapu’s educational and professional training includes forest entomology, insect molecular ecology, biochemistry and insect-plant-virus interactions. She started conducting Christmas tree research when she joined the Whitehill Lab in 2022, where she identified mechanisms of resistance of Fraser fir against the elongate hemlock scale, an invasive insect pest.
Her vision for the OSU Extension Christmas tree program is to improve tree health through interdisciplinary research to develop sustainable management practices and improved genetics. She pivoted from Fraser fir, the most dominant species grown for Christmas trees in North Carolina, to Oregon’s Noble firs and Douglas-firs. There are also Turkish, Trojan and Nordmann firs Landgren brought to Oregon from the mountains of Turkey and the Republic of Georgia to grow and study at NWREC.
Oregon’s Christmas tree growers face several challenges. Extreme weather events, such as record heat waves, have significantly impacted tree health and survival rates. For instance, the summer of 2021 saw record heat that destroyed roughly 70% of young trees. Tree diseases and pests that pose ongoing threats include aphids, twig and root weevils, bark beetles, adelgids and needle midges.
Top priorities: seedlings and pests
Rajarapu’s top research priorities for her first few years are improving tree seedling survival and developing a growing degree day tool for Christmas tree insect pests to improve the efficiency of chemical or biological control. A growing degree day tool is a useful measure in predicting the timing of various life stages of pests that affect these trees and the accurate insecticide application window for an effective control.
For seedling survival, she set up a demonstration plot at NWREC to see what ground cover treatments are best at retaining the moisture in the soil and if any of them effect the seedling physiology.
For pests, she will expand on the work by Landgren and Luisa Santamaria, Extension nursery pathology specialist at NWREC. She plans to hire a graduate student who will scout different locations for pests during the growing season and develop growing degree day models.
She also wants to fill a knowledge gap on the effectiveness and toxicity of pesticide applications, as well as creating more fact sheets for growers.
Rajarapu has also begun working with applied economists in the College of Forestry for cost analyses for growing Nordmann and Turkish firs.
Her overall goal is to support the Oregon and Pacific Northwest Christmas tree industry to help make trees healthier and more abundant, which will make them as affordable as possible to the consumer.
“I like to say that I want a real Christmas tree in every house,” she said.
