Friday, December 30, 2005

A Christmas Tree Threat

Did you find the perfect tree this Christmas? If it was a Fraser fir, consider yourself lucky. As this ScienCentral News video explains, one of America's favorite Christmas trees is under attack… by a fungus.
The Cadillac of Christmas Trees
Picking just the right Christmas tree can be as much of an art form as decorating it. Some people go for the short bushy ones, while for others it's a tall, slender tree with small needles that fits the bill. For those who want a pleasing aroma, dark green color, and needles that don't fall off as soon as your ornaments go on, the Fraser fir (Abies fraseri) is a top choice.
"Fraser firs are considered one of the premier Christmas trees species in the U.S.," says Christmas tree geneticist John Frampton.
But hundreds of thousands of these North Carolina natives are dying. A microscopic fungus called Phytophthora cinnamomi rots away the roots of the trees, and spreads from tree to tree through moisture in the soil. 87 species of Phytophthora have been identified around the globe, and they attack a whole array of plants.
"We estimate that it causes direct losses every year of one and half million dollars," he explains. "Once the Phytophthora is in the soil it makes it impossible to go back and replant Fraser firs in that area."
Frampton and his colleagues from the Department of Forestry and Environmental Resources at North Carolina State University are looking for ways to fight back.
Grafting Fraser seedling onto resistant rootsStudying fir trees from all over the world, Frampton has found several species that have a natural resistance to the fungus. He grew seedlings and inoculated them with Phytophthora cinnamomi to look for resistance. "The most resistant species was Momi fir which is from Japan. Two other fir species that we're interested in are Pindrow fir, from the Himalayan Mountains, and Turkish fir from Turkey," he says.
Frampton has shown that "grafting" Fraser fir seedlings onto the stem and roots of a resistant tree passes on some of the resistance to the Frasers. He has since begun teaching the grafting techniques to local growers.
But, even among the resistant species, some trees are more resistant than others. "We still need to do research to ensure that we can get material that is consistently resistant," he says. So now he's searching for the most resistant trees to use for grafting — based on both genetic makeup and the environment in which they grow. Something he hopes to find by studying the seeds of the Turkish and Trojan firs he recently collected in Turkey.
"We're assembling a collection of seeds with as much genetic diversity of these two species as possible… to understand how resistance to this disease varies geographically. So that we can in the future go back and reliably get resistant material of these two species," explains Frampton.
He plans to grow out trees from the seeds and inoculate them with Phytophthora cinnamomi to look at resistance among the offspring, or progeny, of those trees.
Not Just a Christmas Problem
While a threat to one of the America's top selling Christmas trees is daunting, the stakes are even higher for Frampton's home state. Growing more than 50 million Fraser firs in the mountains, North Carolina is the nation's second largest Christmas tree producer, with a $100 million industry.
Fraser firs dying from Phytophthora root rot.image:North Carolina State University"Fraser is our most important crop in North Carolina. Unfortunately it is also the most susceptible to Phytophthora root rot," explains Frampton's colleague, horticultural scientist Eric Hinesley. "If you get Phytophthora root rot into a field, you are pretty much out of luck. Fungicide is so expensive that it would cost so much to try and get rid of the fungus that you could pretty much buy a new farm."
Phytophthora is believed to have originated in Southeast Asia and have arrived in the U.S. through southern seaports in the 1800's. But it only became a problem for the North Carolina Christmas tree industry in the 1960s when the industry went from using trees from natural groves to plantations.
But this has been a particularly bad year for root rot in North Carolina Fraser firs. The tough hurricane season of 2004 — seven hurricanes and tropical storms hit the state — brought heavy rains and widespread flooding. "We had a lot of flooding that spread the spores of [Phytophthora] around, so this past growing season, this summer of 2005, we've seen a lot of mortality due to Phytophthora root rot," Frampton explains.
Frampton hopes his grafting strategy could make such problems a part of the past, and allow the replanting of Fraser firs in areas currently spoiled by the fungus, preserving what some consider the Cadillac of Christmas trees.
On the other hand, he says the Turkish firs also make some good-looking Christmas trees, so we could one day be adding a bit of an international feel to the holidays.
Frampton's work was presented at the Southern Forest Tree Improvement Conference, June 21, 2005; Limbs & Needles, Vol. 27 (1), 2000; and Limbs & Needles, Vol. 26 (4), 1999. The work is funded primarily by the State of North Carolina, with additional contributions from the Christmas Tree Growers Association and competitive grants.

No comments: