Based on our studies, the major postharvest diseases of dragon fruit or pitaya (Hylocereus spp.) in Taiwan included anthracnose, Alternaria rot, Gilbertella rot, Fusarium rot, Phomopsis rot, Lasiodiplodia rot, and Neoscytalidia rot. Our results showed that fruits were infected either in the field, resulting in latent infection, or during harvesting and formed spots or rotten within three to 14 days postharvest. To control these postharvest diseases, especially against Gilbertella rot and Alternaria rot, disease managements in the field and postharvest practices have been developed and shown reduction of the two diseases during storage. The methods consists of bagging the fruits with water-proved bags 7 days after fruiting, spraying fungicides, such as Bordeaux mixture, cyprodinil and fludioxonil mixture, tebuconazole, and fluaziname, to prevent the pathogens from spreading on flowers or young fruits before bagging, and also treating matured fruits with non-synthetic chemical agents, namely TARI I and II. Furthermore, removing the diseased or non-diseased debris of flowers and fruits in the fields, which would be helpful to prevent the pathogens living as saprophyte, were found to effectively reduce fruit rot during storage.