THE RICE YELLOW MOTTLE VIRUS SITUATION IN WEST AFRICA

The incidence and severity of the Rice Yellow Mottle Virus (RYMV) was monitored in various rice environments in West Africa. Its presence or absence being determined through symptomatology, and serological tests. RYMV was found in all the rice growing environments at different levels of incidence and severity which appear to be dependent on the type of variety planted, the rice environment and the climatic factors under which the rice is cropped. RYMV has been shown to cause losses ranging from 19.5% to 95.5%. Graminaceous weeds including some wild rices have been confirmed as alternate hosts for RYMV. Twenty five rice cultivars consisting of local and locally developed cultivars showed tolerant reactions to RYMV. Most of these varieties showed stable resistance to rice blast in an earlier study. The manifestation of RYMV symptoms on the uninoculated test rice varieties indicated the possibility of the virus being transmitted either through the virus vector or might be seedborne.