Management of pine wilt disease in Korea through preventative silvicultural control

Schematic process of the PWD infection under conventional (A) and silvicultural (B) control protocols. Green circle: normal pine trees, pink circle: first-year PWN-infected pines with wilt symptoms, yellow circles: first-year PWN-infected pines without wilt symptoms, red circles: second-year PWN-infected pines with wilt symptoms, white circles: chemically treated pines, and large white circle: preventative clear-cut area around PWD wilt pines. [Display omitted] ▶ Preventative clear-cutting of neighboring asymptomatic pine trees. ▶ Removal of felled logs or branches. ▶ Through silvicultural control, PWD was successfully suppressed in 11 of 16 districts investigated. ▶ In contrast, successful control was achieved in only 1 among 18 districts subjected to conventional control. Pine wilt disease (PWD) represents a major threat to forest ecosystems worldwide. Although PWD is now better understood, effective control measures for this disease have still not been devised. Here, we report several years of field studies on preventative silvicultural control of PWD. Silvicultural control through preventative clear-cutting and the manual removal of logs was implemented between 2005 and 2009 in 16 Korean districts that had newly PWD-infected stands. Preventative clear-cutting of neighboring asymptomatic pine trees (within a 10–50-m radius of wilt trees) and the removal of felled logs or branches suppressed spread of PWD. Occurrences of PWD wilt pines in districts (city or county) subjected to this silvicultural control method were significantly reduced compared with those in districts using conventional controls (physical or chemical treatment of wilt pine trees). Through silvicultural control, PWD was successfully suppressed in 11 of 16 districts investigated. In contrast, successful control was achieved in only 1 among 18 districts subjected to conventional control. Our results will be of considerable interest to those engaged in the very difficult battle against the global spread of PWD.