Distribution of ryegrass mosaic virus in New Zealand perennial ryegrass pastures as determined by ELISA and RT-PCR

Abstract

Ryegrass mosaic virus (RgMV) is a mite-transmitted member of the Potyviridae that can seriously affect yield and persistence of ryegrass in pastures. To determine the incidence and distribution of RgMV in New Zealand, perennial ryegrass pastures were surveyed by indirect ELISA. RgMV was detected in all seven mature (≥4 years) North Island pastures and 60% of 20 mature South Island pastures, indicating that RgMV is established throughout New Zealand. A reverse transcriptase-polymerase chain reaction (RT-PCR) assay was developed to confirm the identity of RgMV. This assay was 200 times more sensitive than the indirect ELISA. A possible correlation between numbers of the eriophyid mites and the incidence of RgMV was observed in South Island pastures. Our results suggest that mite transmission may be more significant than ryegrass cultivar, pasture age, endophyte infection, or mechanical transmission in defining the incidence and distribution of RgMV. Options for the control of RgMV in New Zealand pastures are discussed. © 1996 Taylor & Francis Group, LLC.