Phylogenetic relationships between viruses related to maize streak virus (MSV). (A) In addition to MSV, there are six other known African streak virus species, including Eragrostis streak virus (ESV), sugarcane streak virus (SSV), sugarcane streak Réunion virus (SSRV), Urochloa streak virus (USV), sugarcane streak Egypt virus (SSEV) and Panicum streak virus (PanSV). Digitaria streak virus (DSV), from the island of Vanuatu in the Pacific, is closely related to the African streak viruses and is included here for reference purposes. This tree has been rooted on the virus Chloris striate mosaic virus (not shown). The boxed area is expanded in (B). (B) There are 11 known MSV strains but only one of these, MSV‐A (in orange), is known to cause severe streak disease in maize. The boxed area is expanded in (C). (C) There are five major MSV‐A variants: MSV‐A6 has only been found on islands in the Indian Ocean; MSV‐A2 has only been found in West Africa; MSV‐A3 has only been found in East Africa; and MSV‐A4 has only been found in southern Africa. MSV‐A1 is found throughout mainland Africa.