Control procedures for PWD epidemics included aerial spraying
of pesticide to kill pine sawyer adults, and physical or chemical
treatment of wilt pines to kill their larvae. Aerial pesticide spraying
began in 1989 following the first PWD detection. Fenitrothion, a
broad-spectrum organophosphate (EXTONET, 2004), was the main
agent in the sprays (Kwon, 2008). Because of fenitrothion damage
on bee farms and other negative environmental impacts, it was
replaced with thiacloprid in 2006. Aerial spraying was conducted
on 3–5 occasions each year (from early June to mid July) over PWD
infected forests and neighboring stands in all PWD-infected districts.
In 2009, pine forests covering 15,000 ha were subjected to
aerial spraying (Korea Forest Service, 2009), although the area of
PWD infected forests in that year was estimated to be only 5633 ha
(Korea Forest Service, unpublished). Information on aerial spraying
is presented