Citrus Tristeza Virus (CTV) and greening bacterium (Liberobacter spp.) are the two major vector-borne pathogens affecting citrus in Reunion island. The surveys carried out since the early 1970's showed a high incidence of the two respective diseases reducing drastically the life-span of newly established orchards. Greening control was achieved through the establishment of a disease free foundation block and biological control of psyllid vectors. An intensive survey covering 6115 trees was conducted in 1995 in the main citrus growing area of the island. It showed that the incidence of greening disease was strongly reduced since less than one percent of the inspected trees were found symptomatic while disease incidence had been estimated to seventy percent before the implementation of the control program. In order to limit the incidence of CTV, an epidemiological study was carried out between 1991 and 1996. Nine newly established citrus orchards were monitored by ELISA. The results showed a very high rate of dissemination of the virus since all trees were completely infected in the first three years following plantation. A population dynamic study conducted in seventeen plots confirmed the strong predominance of Toxoptera citricidus (Kirkaldy) over all the other aphid vectors developing on citrus. Although seasonal variations occurred in T. citricidus populations in relation to tree flushing and presence of natural enemies, colonies of T. citricidus could be observed all year long. Considering the presence of severe stem-pitting isolates disseminated in numerous small orchards and backyards trees, the high rate of virus spread prohibts the plantation of CTV-free susceptible material. Alternatively, the plantation of preimmunized trees enabled the establishment of durably productive Citrus hystrix orchards.