Seoul Intensifies Pine Wilt Control After Infections Surge
Seoul is expanding surveillance and preventive treatment against pine wilt disease after 74 infected trees were found this year, a sharp increase from single-digit totals in each of the previous two years.
SEOUL — The Seoul city government is strengthening efforts to contain pine wilt disease after the number of infected trees detected in the capital rose sharply this year, raising concern for prominent urban forests including the pine groves of Namsan.
Seoul has identified 74 infected trees so far in 2026, compared with five in 2024 and four in 2025. Cases have been found across seven districts: Gangnam, Seongbuk, Gangdong, Dongjak, Songpa, Seongdong and Jungnang.
The latest confirmed case was a tree in Sagajeong Park in Jungnang District on October 13. City officials said it stood about 2.4 kilometers in a straight line from the nearest affected area in Gyomun-dong, Guri, underscoring the risk that the disease could spread into Seoul from neighboring parts of Gyeonggi Province.
Pine wilt disease is caused by microscopic nematodes carried by insects such as pine sawyer beetles. The nematodes enter pine trees and multiply rapidly, disrupting the movement of water inside the tree. Infected trees cannot recover and eventually die, making early detection and containment central to control efforts.
The city trained officials from all district governments, park and recreation centers, and botanical facilities on October 22 and 23 to improve surveillance. It plans to use drones to inspect areas within five kilometers of newly identified cases and conduct checks at least once a month in major parks, forests, hiking trails and roadside plantings.
Namsan will receive heightened protection because of its ecological, cultural and scenic importance. Seoul plans to shorten the interval between preventive tree injections there from once every three years to once every two years. The same two-year cycle will apply at heavily used public spaces including Seoul Forest, Dream Forest, Citizens’ Forest and World Cup Park.
Officials are also considering longer-lasting treatments that can suppress the beetles that transmit the nematodes, with the choice of treatment adjusted according to local risk. Seoul said it will share information with the Korea Forest Service, the National Institute of Forest Science and Gyeonggi Province and activate joint regional measures when necessary.
Next year, the city plans preventive injections for about 120,000 pine trees, alongside continued monitoring and removal of trees considered infected or at high risk. It has also requested central government funding to strengthen control work across the capital. Residents have been asked to report dead pine trees or other trees showing suspicious symptoms.