'Pine Wilt Damage Up 30-Fold in a Year,' Jangseong County Turns to Species Conversion

Surged from over 1,000 to over 31,000 trees in one year
Damage concentrated in forested hills around Nam-myeon, Jinwon-myeon, and Seosam-myeon
Limits of individual-tree felling blamed; disease-control budget to increase

Pine wilt disease is spreading at an alarming rate through forests in Jangseong, Jeonnam-Gwangju, and the number of dead trees has surged more than 30-fold in just one year.

Unable to keep pace with the spread under the limits of the individual control method, which involves cutting down infected trees one by one, the county plans to shift its approach by clear-cutting affected areas and planting different species, a method known as “species conversion.”

On the 13th, trees turned reddish and grayish brown across a forest on a hill in Samgeo-dong, Gwangsan-gu, Jeonnam-Gwangju Integrated Special City, as seen from a drone. Photo by Kim Wanjung

According to Jeonnam-Gwangju Integrated Special City on October 15, as of May this year, 32,252 dead trees had been affected by the disease in Jangseong County. This was an increase of 31,205 trees from 1,047 last year, a 30.8-fold rise in just one year. Compared with 2022, when 500 trees were affected, the number had increased 64.5-fold in four years.

Damage in Jangseong is currently concentrated in forested hills around Nam-myeon, Jinwon-myeon, and Seosam-myeon.

The spread of the damage is attributed to limitations in the disease-control methods.

Until 2024, Jangseong County relied on the existing method of selectively cutting down only infected trees. As a result, it could not stop the rapid spread, and the damage increased rapidly.

Another factor behind the sharp rise in the figures was that, following recent guidelines from the Korea Forest Service, Jangseong County changed how it surveys affected trees. It moved from counting each tree individually, a method known as the “tree-count” approach, to the “sample plot” method, which surveys designated sample areas and uses them to estimate the overall damage. This brought a large amount of previously unrecorded damage to light in the statistics.

Since last year, Jangseong County has been carrying out a large-scale “species conversion” project, clear-cutting forests in infected areas and planting replacement trees resistant to pine wilt disease, including hinoki cypress, tulip trees, and sawtooth oaks. The project is focused on clusters of affected areas typically covering at least 3 hectares, with the consent of forest owners.

Experts point to the complete suspension of aerial pest control in forests in 2023, amid environmental concerns such as honeybee deaths and opposition from beekeeping farms, as a key factor. Pine wilt nematodes cannot move on their own and spread through insect vectors such as the Japanese pine sawyer beetle. Experts say that the suspension of aerial control prevented authorities from keeping beetle populations in check, worsening the damage.

There is no treatment for pine wilt disease once a tree is infected, leaving felling the entire tree as the only clear option. Preventive measures such as trunk injections are available, but applying them across vast areas of forested hills is not practically feasible.

In response, the county is gradually increasing its budget for disease control. Next year, it plans to focus species conversion efforts on areas severely affected in Nam-myeon, Jinwon-myeon, and Seosam-myeon, as well as areas near planned national industrial complexes. However, around residential areas, protected trees, and major cultural heritage sites, it will work to preserve forests by combining the existing method of felling individual trees with trunk injections.

“Pine wilt nematodes cannot move on their own, so controlling populations of insect vectors such as the Japanese pine sawyer beetle is central to disease control,” said Kim Jungtae, head of Gwangju Tree Hospital. “Aerial pest control was completely suspended in 2023 due to opposition from beekeeping farms and other concerns, creating a gap in efforts to control the insect vectors. As a result, the damage spread out of control.”

A Jangseong County official said, “Given the nature of pine wilt disease, for which there is no treatment, felling individual trees has limited effectiveness in stopping its spread. We are implementing a fundamental disease-control strategy through the species conversion project. We will swiftly carry out reforestation with replacement species, focusing on the most severely affected areas and major industrial complexes, to quickly establish healthy replacement forests.”

This content was produced with the assistance of AI translation services.