Groundnut rosette virus (GRV) is a peanut pathogenic virus found in Sub-Saharan Africa. It is transmitted between plants by insect vectors such as the groundnut aphid (Aphis craccivora). History The groundnut (Arachis hypogaea) originated in South America where it has long been domesticated. More recently it has been cultivated in other parts of the world and is an important subsistence crop in Sub-Saharan Africa. Groundnut rosette virus was first described in Africa in 1907 and causes serious damage to groundnut crops on that continent. In 1939 it was reported to infect 80 to 90% of plants in the Belgian Congo causing major losses in yield. The virus can spread rapidly through a crop. In a study in Tanzania, the first affected plants were seen six days after the first aphids were observed. Aphid numbers built up rapidly and the disease increased tenfold in two weeks with 65% of the crop plants affected three weeks later. Symptoms Research has shown that plants infected by groundnut rosette virus alone show little or no effect, but that the symptoms of the disease are caused by a satellite RNA co-infection, a subviral agent. Groundnut plants affected take on a bushy appearance due to stunting and distortion of the growing shoots. There is a yellowing or mottling of the foliage. Plants affected when young may produce no nuts. There are three main types of symptoms: Chlorotic rosette is common in many parts of sub-Saharan Africa. Young leaflets become slightly mottled, and older leaflets become chlorotic with green veins. In young plants the leaves become increasingly yellow, twisted and stunted, but in older plants a few branches or just the growing point may be affected. Mosaic rosette is prevalent in East and Central Africa. Young leaves have a green and yellow mosaic appearance and later symptoms resemble those of chlorotic rosette but the plants are less severely stunted. Green rosette is known from West Africa, northern Malawi, Uganda and possibly Angola. Younger leaves show some mottling and flecking while older leaves are small and very deep green and have inrolled margins. The plants are severely stunted and resemble plants infected with peanut clump virus. The chlorotic and green types are caused by two variants of the satellite RNA while the mosaic type is caused by infection with a mixture of both variants. Further research has shown that another virus, groundnut rosette assistor virus (GRAV), is also