Citrus is an important tropical fruit in Taiwan. The cultivation area is ca 26,145 ha with fruit yield of ca 528,254 tons/year. Within the service area of Tainan DARES, it has ca 11,458 ha or 44% of the total in Taiwan, with fruit yield of 289,266 tons/year. The major varieties are Liucheng or sweet orange, 5,034 ha; Pokan, 3,347 ha; Mato Wentan, 1,314 ha; and Mato Peiyu, 453 ha. The production season is from September to January of the next year. They are mainly for inland consumption and parts for export. The major cultivation areas are Yuinlin, Chiayi and Tainan. In order to increase the competitiveness of citrus industry, research is focused on the improvement of soil and fertilizer application, integrated pest management, twig pruning technique to assist farmers in the improvement of production environments as thus, to improve its yield and fruit quality.