First report of Iris yellow spot virus on onion in Canada
In North America, Iris yellow spot virus (Tospovirus, IYSV – EPPO Alert List) which is transmitted by Thrips tabaci, has spread rapidly in Western USA and Georgia. In Canada, onion plants showing symptoms resembling those of IYSV were observed in June and July 2007 in Ontario. Symptomatic onions plants which had been grown from sets were observed in a household garden in Grey County and on a small commercial farm in Ottawa-Carleton County. In the household garden, bleached, elongated lesions were observed on middle-aged leaves on about 30% of the plants. By the beginning of August 2007, approximately 90% of the plants were showing symptoms. In the commercial farm, lesions were seen on a single plant (in a field of 1,120 plants). Laboratory tests (DAS-ELISA) confirmed the presence of IYSV. These isolated finds prompted a survey in early August 2007 in the largest onion-producing region of Ontario (Holland Marsh). Nine onion fields were inspected and the presence of IYSV was confirmed by DAS-ELISA and RT-PCR in 7 fields. This is the first report of IYSV in Canada. The authors considered that the finding of IYSV in remote and isolated locations where onions were grown from sets implies that the possible spread of IYSV via infected bulbs deserves further investigations.
The situation of Iris yellow spot virus in Canada can be described as follows: Present, first found in 2007 in seven onion fields in Ontario.
Hoepting CA, Allen JK, Vanderkooi DK, Hovius MY, Fuchs MF, Pappu HR, McDonald MR (2008) First report of Iris yellow spot virus on onion in Canada. Plant Disease 92(2), p 318.