Recent developments in grass virus research in Britain

Ryegrass mosaic virus (RMV) and barley yellow dwarf virus (BYDV) are the most prevalent and important viruses that attack ryegrass (Lolium spp.) in Britain. In studies on the importance of transmission of RMV mechanically and by the eriophyid mite Abacarus hystrix (Nal.), it was found that, in the absence of mites, the virus was not spread by grass cutting machinery either within plots containing diseased plants or to healthy plots. Soil application of aldicarb, and spray applications of endosulfan and menazon to plots of ryegrass containing 50% infected plants one year after sowing decreased percentage viral incidence to 0, 25 and 44, respectively. Two new species of virus that attack ryegrass in Britain are described.