Rice yellow mottle virus (RYMV), first described in Kenya in 1970, is now known to occur widely both in East and West Africa. It represents a major threat to improved rice cultivation under irrigated conditions, particularly when the new, high-yielding varieties introduced from Southeast Asia are grown.
African soybean dwarf is a new and hitherto undescribed virus disease which until now has only been reported in Nigeria. The disease is whitefly-borne and appears to represent a major threat to soybean production of highly susceptible varieties which are newly introduced and have not been sufficiently tested.
At the International Institute of Tropical Agriculture (ITTA) at Ibadan, Nigeria, breeding programs on rice and soybean have taken both diseases into account. New genotypes being developed for international adaptive testing and release as improved varieties are being selected for various desirable characters, including resistance (tolerance) to these potentially disastrous virus diseases.