Further studies on rice stripe necrosis benyvirus in Colombia
Since 1991, a new rice disease has been observed in the Department of Meta, Eastern Plains of Colombia. Symptoms are characterized by death of seedlings, stripes on the leaves and severe plant malformation (including leaf crinkling, hence the Spanish name 'entorchamiento'). By 1994, the disease had spread to most of the rice-producing municipalities of this region, causing yield losses of more than 20 % (see EPPO RS 97/019). The disease was thought to be caused by rice stripe necrosis virus (EPPO Alert List), a virus transmitted by Polymyxa graminis, which was previously only reported from West Africa. Further investigations were conducted in Colombia and they confirmed that the disease is indeed associated with rice stripe necrosis virus and the fungus P. graminis. Morphological characteristics of the Colombian isolate are similar to those of the African isolate studied. It is felt that rice stripe necrosis virus probably belongs to the new Benyvirus group. It is also observed that this virus is now present in the main rice-growing departments of Colombia (Huila, Tolima, Meta, Casanare, Antioquia, Cordoba, Cundinamarca), and that the distribution in Latin America might be broader than currently known. The authors noted that the main factor responsible for the relatively rapid spread of the disease in Colombia seems to be the shared use of contaminated agricultural machinery by rice growers. This disease is considered as a potential threat to the rice production in Latin America. Once viruliferous fungi invade a cultivated soil, it is virtually impossible to eradicate the virus. Control methods will probably rely on the use of resistant rice cultivars which are currently being developed in West Africa.
Sources
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Morales, F.J.; Ward, E.; Castaño, M.; Arroyave, J.A.; Lozano, I.; Adams, M.J. (1999) Emergence and partial characterization of rice stripe necrosis virus and its fungus vector in South America.
European Journal of Plant Pathology, 105(7), 643-650.
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