Temporal and spatial dispersal of Melon yellow spot virus in cucumber greenhouses and evaluation of weeds as infection sources

Surveys conducted in Melon yellow spot virus (MYSV)-affected cucumber greenhouses revealed that the incidence of MYSV disease on cucumber plants varied by crop management conditions. Because of temporal and spatial dispersal of viruliferous Thrips palmi in two greenhouses, MYSV was detected in 21.2% of the cucumber plants growing in a weedy greenhouse and in only 1.3% of the cucumber plants growing in a thoroughly weeded greenhouse at the end of the cropping period. MYSV was also detected in 13 weed species found outside the cucumber greenhouses. Viruliferous T. palmi adults were often found on Acalypha australis, Cerastium glomeratum and Lamium amplexicaule. T. palmi reared on MYSV-infected cucumber plants transmitted MYSV to C. glomeratum and L. amplexicaule. Moreover, T. palmi reared on MYSV-infected C. glomeratum rarely transmitted MYSV to cucumber seedlings. These results suggest that weed control is important for managing MYSV since weeds provide a habitat for the vector thrips and also serve as an initial inoculum source of the virus.