Iris yellow spot virus detected on Eustoma in the Netherlands
In October 2006, during a survey for Iris yellow spot virus (Tospovirus, IYSV – EPPO Alert List) the virus was detected in a crop of Eustoma (lisianthus) in the Netherlands. These ornamental plants were grown for sale to home consumers. IYSV was detected by DAS-ELISA (with specific antisera) and the virus identity was confirmed by inoculation to Nicotiana benthamiana and DAS-ELISA testing of symptomatic plants. Affected Eustoma plants (a white and a purple cultivar) showed necrotic spots on the leaves and longitudinal necrotic streaks on the stems. Diseased plants were clustered in small groups and the occurrence of symptoms was associated with a high incidence of Thrips tabaci. It is suspected that the virus was introduced into the crop via viruliferous thrips. After controlling the thrips, the number of infected plants no longer increased. No particular phytosanitary measures have been applied to the crop, as IYSV is not regulated. A Pest Risk Analysis (PRA) is under way but because there are still uncertainties about geographical distribution, host range, pathway for spread, and economic impact of the virus, it remains difficult to conclude on the risk and appropriate phytosanitary measures. This is the first report of IYSV on Eustoma in the Netherlands, although IYSV has already been reported on this plant in Israel (EPPO RS 2001/052) and Japan (EPPO RS 2004/160). In the Netherlands, isolated findings had earlier been made on Iris (1992), Allium porrum (1997), Alstroemeria (2004, 2005) and Allium cepa (2005, 2006).
The pest status of Iris yellow spot virus in the Netherlands is officially declared as follows: Present, incidental findings.
NPPO of the Netherlands, 2007-01.