New virus disease of rice in Colombia
Until recently, the only virus of rice present in Latin America was rice hoja blanca tenuivirus (RHBV), which is transmitted by a planthopper Sogatodes oryzicola. However, in 1991, a new disease of rice was observed in the eastern plains of Colombia. Infected plants showed striking symptoms. Emerging central leaves are highly deformed, showing a 'zigzag' growth (hence the common name 'entorchamiento': crinkling). Affected leaves show chlorotic or yellow stripes and later become necrotic. Plant growth is severely reduced, and when affected at an early stage, seedlings may die. The incidence of this disease increased from an average of 6 % in 1993 to 18 % in 1994, in areas where it first appeared. Yield losses associated with the presence this disease in Colombia have been estimated at 20-40 %, and some rice fields in the Eastern plains have even been abandoned. Morales et al. (1995) identified the causal agent of this new disease as being the rice stripe necrosis furovirus (RSNV). This virus had previously been reported from West Africa only and is probably transmitted by a fungus, Polymyxa graminis. It was first reported in 1977 in Côte d'Ivoire, and then in Liberia, Nigeria, Sierra Leone (Hibino, 1996). The virus and its fungal vector have now been identified in all the major rice-producing regions of Colombia. It is suspected that this new virus disease may have been introduced into the country on rice germplasm material from Africa.
Sources
Hibino, H. (1996) Biology and epidemiology of rice viruses.
Annual Review of Phytopathology, 34, 249-274.
Morales, F.J. (1996) Rice virus emerges in Latin America.
CARAPHIN News, no. 14, p 4 ; 8.
Morales, F.J.; Arroyave, J.A.; Velasco, A.C.; Castano, M. (1995) [Partial characterization of crinkling or necrotic stripe virus on rice in Colombia.]
Fitopatologia Colombiana, 19(1), 48-54.