The transmission and effect on yield of ryegrass mosaic virus in a filtered air environment

The eriophyid mite vectors of ryegrass mosaic virus (RMV) were excluded from ryegrass by covering plots with a polyethylene film house ventilated by filtered air. Initially plots were manually inoculated to give different levels of RMV. During two seasons no mites were found within the house so that all transmission of virus was by sap. Rolling and frequent cutting of uninfected plots decreased yields, but surprisingly, increasing virus infection did not decrease yields significantly. Cutting transmitted virus within infected plots but not from infected to healthy plots, whereas combined rolling and cutting did transfer virus to healthy plots.