Presently, the only possibility to protect susceptible
commercial varieties from virulent CTV isolates
is classical cross protection with mild CTV isolates
(Costa and Müller 1980). Although it has been successfully
used to protect Pera sweet orange (C. sinensis
(L.) Osb.) in Brazil, and Marsh grapefruit (C.
paradisi Macf.) in South Africa (Van Vuuren et al.
1993), protection afforded is sometimes temporal.