Inoculum Sources to Generate High Mechanical Transmission of Barley yellow mosaic virus

Mechanical transmission of barley seedlings with barley yellow mosaic virus (BaYMV) is generally inefficient and is the major constraint for testing cultivar resistance to the virus. To explore mechanical transmission, BaYMV-infected barley plants were grown at different conditions and used as inoculum sources to seedlings of susceptible barley cultivar Baegdong. Extracts prepared from BaYMV-infected Baegdong plants at 47, 53, 74, and 90 days after symptom appearance (DASA) and grown at 10 and $12^{\circ}C$ gave 10, 30, 68 and 76% infection, respectively on inoculated susceptible barley cv. Baegdong seedlings. While Jinyangbori, another susceptible cultivar obtained 95% infection rate inoculated with extracts from 90 DASA disease source and grown at $10/12^{\circ}C$. However, low infection rates were obtained when the virus sources were grown in a greenhouse at $15-18^{\circ}C$. Our results indicate that longer incubation period and lower temperature are required for virus accumulation and stability.