Introduction. Citrus tristeza virus (CTV) and huanglongbing bacteria are the two major pathogens affecting citrus in Reunion island. Control of citrus huanglongbing. In the 1970s, an epidemiological study showed that, 7 years after plantation of healthy trees, the rate of huanglongbing contamination amounted to 65% of individuals. A control strategy was therefore developed, based on the careful disease-free management of foundation block and nurseries, combined with biological control of the vectors. Ten years after the release of exotic parasitoids of psyllids, the two huanglongbing vector population were consistently reduced thus enabling the development of a profitable citrus industry. This was confirmed by a recent survey of the orchard established with this new strategy. Epidemiology of CTV. To set up an adapted control strategy, the spread of CTV was studied in various ecological conditions of the island. The kinetics of tree contamination by CTV showed a high rate of virus infection. In 1994, a survey was aimed to assess the population dynamics of aphids on citrus in relation with tree phenology and orchard management. The large predominance of Toxoptera citricidus (Tc) as compared to other aphid vectors was confirmed. Although seasonal variations occurred in Tc populations in relation to tree flushing and the presence of natural enemies, colonies of Tc could be observed all year round. Conclusion. Considering the presence of severe stem-pitting isolates disseminated in numerous small orchards and backyards trees, the high rate of virus spread prohibits the plantation of CTV-free susceptible material. Alternatively, the plantation of pre- immunized trees enables the establishment of durably productive Citrus hystrix orchards.