Symptoms: The symptoms of brome mosaic virus (BMV) are similar to those of WSMV. Yellow or white spots and streaks rapidly spread over the leaves initially born a yellowish mosaic pattern. The leaves will rapidly become bright yellow. Infected plants may be slightly stunted and produce shrivelled grain. Young plants exhibit the most obvious symptoms and these become less apparent as the plants grow older. Some wheat lines may be symptomless carriers.
Vectors: In the laboratory, nematodes of the genus Xiphinema have been shown to transmit the virus. Laboratory transmission by aphids and mites has been unsuccessful, but recently the aphid Diuraphis noxia has been reported to transmit the virus.
Hosts/Distribution: BMV infects wheat, oats, maize, barley, rye, and in additional species of Bromus, Lolium, Phleum, Agropyron, Agrostis, and Poa. Diagnostic species are: maize (Zea mays), in which the seedlings of most lines show primary lesions or streaks followed by necrosis and death, and Chenopodium spp. BMV is one of the few grass viruses that cause local lesions on C. amaranticolor, C. hybridum, and C. quinoa. BMV has been reported to occur in nature in Finland, South Africa, the central United States, Canada, Russia and the former USSR, and the former Yugoslavia.
Importance: BMV had not been thought to be important or to cause economic loss in cereals, but reports suggest it may be much more widespread than thought and may be damaging in South Africa.
