In 1966, the outbreak of a rust disease was discovered from the young plantation of Taiwan red pine (Pines taiwanensis Hay.) at the northeastern part of Taiwan Island. The plantation of about 2,000㏊ planted with 3-4 years old saplings is located on the mountain slopes of a valley of the upper stream of Ta-Chia River. The rust disease was first discovered sporadically from the narrow margin of plantation surrounding the pine nursery which was located at the center of valley. The disease spread rapidly and the total infected area in 1968 had been recorded for 186 ha. The rust fungus was first identified as Cronartium ribicola J.C. Fischer. The alternative hosts of this rust fungus, Ribes spp. were not recovered from the area of infectian sites nor from the area of 20Km radius from the infected site. Instead of Ribes host, Paeonia suffruticosa Andr. were planted in the nursery near by the pine nursery from 1966. It was thus identified the rust fungus as Cronartium flaccidum (Alb. et Schw.) Wint. The extensive control measures were practiced from 1968 and the eradication of infected saplings, shrubs and weeds of forest floors was given the first priority. In total, 111,852 trees infected were felled down from 1966 to 1971. All infected branches or parts of the trees were first wrapped with the vinyl film to prevent the dispersion of rust spores and then trees were felled down and finally were burnt at the site. Rest of pine trees of the whole plantation were sprayed with the fungicides; 0.2% Dithane Z-78 or 4-4 Bordeux mixture with addition of 1% Uspulun. Spraying of fungicides was carried out at least twice a month and continued to 1971. In 1973 and 1974, reforestation by some resistance tree species such as Pines armandi Fr., Taiwania, Cryptomeria, or Chamaecyparis, etc, were practiced. In total, 148,500 seedlings of tree species mentioned above were replaced the infected pine trees. Since the first outbreak of the disease in 1966, 20 years have been passed without any new outbreak of the rust disease by C. flaccidum in the same site or any other plantations in Taiwan. The control of the rust disease erupted in Taiwan red pine plantation in 1966 in thus concluded as very successful.