First report of Iris yellow spot virus in South Africa
In South Africa, typical symptoms of Iris yellow spot virus (Tospovirus, IYSV – EPPO Alert List) were observed in an onion (Allium cepa) seed crop in the region of Klein Karoo (Western Cape Province), in December 2006. The crop was 2 to 3 weeks from harvest and at the time symptoms were observed, approximately 5% of the scapes (seed stalks) had lodged because of the presence of extensive lesions. Symptomatic tissues from 2 plants were tested (RT-PCR, sequencing) and the presence of IYSV was confirmed. In South Africa, approximately 6 100 ha of onion bulb crops are grown annually in the Western Cape, Kwazulu Natal, Limpopo, and Northern Cape provinces, and 600 ha of onion seed crops are grown primarily in the semi-arid regions of the Western Cape. Examination of an additional 10 onion seed crops in the Klein Karoo region in January 2007 revealed the presence of IYSV in three more crops (with a disease incidence of approximately 5%). This is the first report of IYSV in South Africa.
The situation of Iris yellow spot virus in South Africa can be described as follows: Present, first found in 2006 in four onion crops, Western Cape Province.
du Toit LJ, Burger JT, McLeod A, Engelbrecht M, Viljoen A (2007) Iris yellow spot virus in onion seed crops in South Africa. Plant Disease 91(9), p 1203.