Plant Disease (2012) 96, 1165-1171

C. Nischwitz, R. Srinivasan, S. Sundaraj, S.W. Mullis, B. McInnes and R.D. Gitaitis (2012)
Geographical distribution and survival of iris yellow spot virus in spiny sowthistle, Sonchus asper, in Georgia
Plant Disease 96 (8), 1165-1171
Abstract: Iris yellow spot virus (IYSV) has occurred in Georgia since 2003. IYSV is transmitted by onion thrips, Thrips tabaci. During a weed survey in the Vidalia onion-growing zone (VOZ), spiny sowthistle (Sonchus asper) was identified as a host for IYSV. Spiny sowthistle is widespread in Georgia, and this presented an opportunity to study the natural spread of IYSV and assess its potential role in IYSV epidemiology. From 2007 to 2009, during the spring season, 2,011 sowthistle samples were collected from various counties within and outside the VOZ. The samples were tested for IYSV infection by enzyme-linked immunosorbent assay and confirmed by reverse-transcription polymerase chain reaction and sequencing. IYSV sequences from sowthistle were 98 to 99% identical to onion IYSV sequences from onion originated from Georgia. By the third year, IYSV-infected sowthistle plants were found in 79% of the counties in the VOZ and in 61% of the sampled counties in all directions, except to the east of the VOZ. Furthermore, thrips-mediated transmission assays confirmed that T. tabaci can efficiently transmit IYSV from onion to sowthistle. Sowthistle also supported T. tabaci survival and reproduction. These findings demonstrate that sowthistle plants can serve as an IYSV inoculum source and as a thrips reservoir.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Claudia Nischwitz

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution
environment - cropping system/rotation

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sonchus asper (weed)		U.S.A. (SE)
	Orthotospovirus iridimaculaflavi	Onion/garlic/leek (Allium)	U.S.A. (SE)