'A sea of fire': Pine wilt disease ravages national parks nationwide

GYEONGJU, North Gyeongsang — Pine trees that should have been green all year long at Gyeongju National Park in Gyeongju, North Gyeongsang, had turned a faded red even before the autumn foliage season began.

“Gyeongju is already a sea of fire,” a forestry engineer said while pointing to the dying pine trees on Mount Nam.

And the culprit — pine wilt disease — is spreading rapidly through the area.

“We need to slow the infection if we’re going to save the pine trees around cultural heritage sites, but [the disease] is sweeping through [the trees] like a typhoon. There’s little that we can do,” Jeong Gyu-won, the park’s forestry engineer, said. “At this rate, Gyeongju’s pine trees […] could disappear altogether.”

Pine wilt disease has spread beyond the southeastern region to the entire country, with even centuries-old pine trees succumbing to nematodes, similar to parasitic worms, that measure only 1 millimeter (0.04 inches) in length.

Dead pine trees or those suspected of being infected with the disease have been found in 11 of Korea’s 23 national parks, according to the Korea National Park Service on Tuesday.

The disease has reached Jirisan National Park, the country’s first national park; Mount Songni and Mount Worak in the central Chungcheong region; and even Mount Bukhan in Seoul.

The epidemic is especially serious because pine trees carry deep cultural significance in Korea. A pine tree appears in the second verse of the national anthem as a symbol of steadfastness and resilience, as it endures wind and frost.

Gyeongju turns red as nematodes kill 400-year-old pines

But the damage is most severe in Gyeongju National Park.

More than 15,000 trees were cut down in the first half of this year after becoming infected with pine wilt disease, but authorities have been unable to contain the spread.

Mount Nam, the entirety of which is designated both as a Unesco World Heritage site and a national park, has not escaped what some describe as a “pine pandemic.”

Dead trees are scattered throughout Samneung Forest, which is widely known through the photos taken by renowned photographer Bae Bien-u.

“The pine sawyer beetles that carry the nematodes […] detect the smell of dying pine trees and fly toward [the scent],” forestry engineer Jeong said. “Mount Nam is a rocky area, so it is difficult for us to seal the trees to fumigate them. The smell of dying trees released during [disease] control methods that use netting may have also drawn even more beetles toward Mount Nam.”

Four-hundred-year-old pine trees at Jungheung Temple, located near the entrance to Mount Nam, have also died and will soon be cut down.

“We cried out for someone to save the pine trees and went everywhere asking for help, but in the end, we couldn’t save them,” said Venerable Yejin, the temple’s head monk. “You could almost say that this temple was built because of those pine trees. I don’t know how we’re supposed to bring ourselves to cut them down.”

The damage has recently spread to pine forests around major cultural heritage sites in Gyeongju, such as 1,250-year-old Bulguk Temple and the royal tombs.

The pine forest surrounding the tomb of Gen. Kim Yu-sin, a general from the ancient Silla Dynasty (57 B.C. to A.D. 935), in Gyeongju was still entirely green in August. Less than two months later, the forest seems almost ablaze in red, as if a wildfire has torn through.

Climate change deepens control dilemma

Pine wilt disease is incurable. Once a tree is infected, the mortality rate is a whopping 100 percent.

The nematode travels from tree to tree through carrier insects such as pine sawyer beetles. Once settled, they block the pathways that carry water and nutrients through the tree, which causes the pine to dry out and die.

Disease control authorities have struggled to keep pace with the spread. Drought and high temperatures have expanded carrier insects’ active season and flight range, and available control methods have limitations.

“Pine wilt disease is spreading almost by the day because of extreme heat and drought,” said Kim Jeong-gyu, the head of Gyeongju’s forest disaster prevention team. “Gyeongju has not only a national park but also many cultural heritage protection zones, so there are numerous restrictions on control work. That makes it difficult to stop the spread.”

Some also point to the suspension of aerial pesticide application as another factor that has weakened efforts to contain the disease. The Korea Forest Service halted the practice nationwide in 2023 because of concerns about its impact on ecosystems, especially on honeybees.

Only four national parks had confirmed cases in 2022. The figure doubled to eight last year, and three more parks — Mount Jiri, Mount Bukhan and Mount Songni — have reported infections this year.

The discovery in Jirisan National Park marked the first confirmed case there in 18 years, with the last report in 2008.

Bukhansan National Park, the only national park in the Seoul metropolitan region, also found a dead tree infected with pine wilt disease for the first time since 2014.

The disease has moved steadily north. About 120,000 infected trees were found in Gyeonggi this year, an increase of nearly 70 percent from last year.

Eradication is impossible

Experts warn that Korea’s forest ecosystems could change rapidly if the disease continues to spread.

“A wildfire ends once it passes, but pine wilt disease keeps spreading as long as trees remain,” Seo Jae-cheol, a representative of Green Korea United, an environmental preservation advocacy group, said. “Entire pine forests could disappear.”

“Monitoring and research by the Ministry of Climate, Energy and Environment are urgently needed to understand how forests in national parks will change because of the disease,” Seo continued.

There are also concerns that the combination of climate change and pine wilt disease could accelerate the disappearance of pine forests.

“Pine forests currently account for about 20 percent of Korea’s forests, but that share could fall to around 10 percent,” said Prof. Oh Choong-hyeon in the Department of Biological and Environmental Science at Dongguk University.

“The reality is that eradicating pinewood nematodes is virtually impossible. We need a strategy of selection and concentration that focuses on areas where pine trees must be preserved.”

BY CHON KWON-PIL [[email protected]]