Incheon marks 38 years without pine wilt disease as infections spread nationwide

Incheon has recorded no pine wilt disease infections in the 38 years since the disease first appeared in South Korea, even as damage spreads nationwide, Yonhap reported, citing the Korea Forest Service. Nationwide, infected trees totalled 1,772,985 in the year from June last year to May this year, the agency said. The disease was first detected in 1988 at Geumjeongsan in Busan and has since spread across the country; of the 16 metropolitan cities and provinces, all except Incheon have recorded infected trees. [ 2 , 3 ]

There is no way to treat an infected pine, which dies in 100% of cases, according to Yonhap. The disease spreads naturally through vector beetles such as the Japanese pine sawyer and the northern pine sawyer, or when infected trees are moved by people. Hankook Ilbo also published a photo caption saying pines on a hill in Myeongdo-dong, Gwangsan-gu, in the Jeonnam-Gwangju integrated special city, had withered from the disease two days earlier. [ 2 , 3 ]

The exact reason Incheon has escaped the disease has not been identified. Pine forest covers 7,529 ha, or 19.1% of Incheon's 39,373 ha of forest, 8.4 percentage points below the national average of 27.5%, according to forestry statistics cited by Yonhap; the report said the smaller share of susceptible trees may have played a role but did not confirm it as the cause. Hankook Ilbo described as a leading theory that the city has many islands and coastal areas and relatively few large-scale forests. [ 2 , 3 ]

In April, the disease was detected for the first time in Jeongwang-dong, Siheung, Gyeonggi Province, next to Incheon. Hankook Ilbo reported that Siheung and Incheon share living zones and green belts, which it said raised the risk of infection. Incheon carried out intensive surveillance in parts of Namdong-gu near Siheung and has found no infections, and the Incheon Grand Park office and the Seoul National Forest Management Office tested 73 dead or suspected trees in the city this year, all free of the disease. The city also checks the production certificates required when pine products are moved from other regions and visits timber and landscaping companies to hand out notices on blocking infected trees, according to Yonhap. An Incheon city official told Hankook Ilbo that the city is still maintaining clean status but that stricter management is needed, and that measures to block the disease at source are being strengthened. [ 2 , 3 ]

Nam Young-woo, a forestry researcher at the National Institute of Forest Science, told Yonhap the reason Incheon has not had an outbreak is hard to explain clearly, adding that the city has environmental conditions in which the disease could occur and should pay more attention to surveillance. He called for preventive injections focused on forests that must be protected, rapid testing of dead trees, and management of human-driven spread such as movement from other regions. Kukmin Ilbo reported that experts also do not know the reason for Incheon's record. [ 1 , 2 ]