Technical Abstract: Within the last ten years the greenhouse whitefly (Trialeurodes vaporariorum) has been emerging as a serious threat to vegetable and fruit production in not only greenhouse, but also field agriculture, particularly along the west coast of North America affecting numerous vegetable and fruit crops. Although greenhouse whiteflies (GHWF) themselves can cause significant damage and loss, this is compounded by the losses resulting from GHWF-vectored viral diseases that are much more economically damaging than losses from vector feeding alone. All known GHWF-transmitted viruses are in the genus Crinivirus (Closteroviridae). Criniviruses typically cause symptoms including interveinal yellowing of leaves, an associated loss of photosynthetic capability, leaf brittleness, yield reductions and early senescence. Four GHWF-transmitted Crinivirus species have been identified. These include Beet pseudo yellows virus (BPYV), Strawberry pallidosis associated virus (SPaV), tomato infectious chlorosis virus (TICV), and Tomato chlorosis virus (ToCV). Molecular and serological tools have been developed for detection of these viruses. There are currently no commercial sources of resistance to any of these viruses, and little resistance has been identified in wild germplasm. Control is through management of the GHWF vector. Vector control is only partially effective in reducing virus spread, as transmission can occur during feeding periods of less than 24 hours by very few whiteflies. Management is even more difficult in organic and reduced chemical agriculture.