Approximately 3,800 species of forest insect pests and diseases are identified in Korea, of which about 20 species cause direct damages to trees. Of these, pine wood nematode, pine needle gallmidge, black pine bast scale and Korean oak wilt are under integrated management of the KFS. In 2005, the outbreak of pine wood nematode, which was first detected in Busan in 1998, damaged 566,000 trees nationwide. The Special Act on the Extermination of Pine Wilt Diseases was enacted in 2005 to prevent further damage and as a result, the number of affected trees decreased to 16,000 in 2010.
Pesticides were used widely for controlling pine needle gall midge and black pine bast scale, but forestry control measures are being implemented Since 2009 to maintain forests' ecological health. The area of pine needle gall midge and black pine bast scale outbreaks still decreased significantly from 196,000 ha in 2006 to 113,000 ha In 2010 and from 45,000 ha in 2006 to 22,000 ha in 2010, respectively. The number of trees damaged by the Korean oak wilt rapidly increased to 194,000 in 2006 and to 298,000 in 2008. Clear-felling method was used to reduce further damage and the number decreased to 181,000 trees in 2010.