Cabbage plant from a farm in Buckup, St Elizabeth, with cabbage leaf curl disease (CaLCD). No cabbage 'head is formed'.
SINCE THE 1990s, the production of some vegetable crops in Jamaica has been reduced due to whitefly transmitted geminiviruses. Geminiviruses are plant viruses that cause epidemics in food crops. Using biotechnology, more than 20 viruses from Jamaica infecting vegetables (six viruses) and weeds (18 viruses) have been identified by the GSI (geminivirus scene investigators) at the Biotechnology Centre at the University of the West Indies.
The crop viruses include bean golden yellow mosaic virus (BGYMV) which infects red peas and broad beans causing a yellow mosaic pattern on the leaves. This virus is the major limiting factor in red peas production accounting for a 60 per cent reduction in red peas in Jamaica since 1993. This has resulted in the importation of red peas to meet local market demands.
Two geminiviruses tomato yellow leaf curl virus (TYLCV) and tomato mosaic Havana virus (ToMHV-[JM]) were found infecting tomato and scotch bonnet pepper. Symptoms include leaf curling and severe stunting. TYLCV is the most devastating virus infecting tomato. TYLCV alone, or with ToMHV-[JM], causes the 'Jherri curl' disease in Jamaica. There are several tolerant tomato varieties in Jamaica including Gempride, Gempear and Adonis and farmers are advised to plant these instead of susceptible ones such as Castlerock and Flordale.
CABBAGE LEAF CURL DISEASE
Two geminiviruses cause cabbage leaf curl disease (CaLCD) in cabbage and cauliflower. Cabbage plants infected with CaLCD have leaves that curl up instead of folding into a compact 'head' which means the farmer has no marketable product. Farmers in Douglas Castle indicated cabbage varieties such as Resist Crown and Tropicana are tolerant to the disease and should be planted by farmers instead of susceptible varieties such as KY and KK. There are data which suggest that the cabbage viruses also infect broccoli and this is being investigated by the GSI.
In Jamaica, numerous weeds, including milkweed and broomweed, are infected with geminiviruses. Some scientists have suggested that many of the viruses in the crops may have evolved from the weed viruses. In Jamaica, some weed viruses are able to infect crops in the laboratory and this is being investigated by the GSI.
