Iris yellow spot virus on Onion in New Mexico

Abstract

Onions are an important crop for New Mexico with 7,700 acres (3,116 ha) harvested in the state in 2003 (3). In 2002, onions of several cultivars were first noticed with diamond-shaped chlorotic or bleached lesions on seed stalks or leaves, typical of those reported for Iris yellow spot virus (IYSV). A more widespread survey of breeding stocks and commercial onion fields revealed similar symptoms on thrips-infested onions in Dona Ana and Rio Arriba counties. Incidence of disease symptoms ranged from <0.5 to nearly 30%. Symptomatic leaves were assayed for the presence of IYSV using enzyme-linked immunosorbent assay (ELISA; Agdia, Elkhart, IN) and antisera acquired from Agdia. Symptomatic leaves from breeding and commercial fields tested positive for IYSV. The virus was transmitted by Thrips tabaci from symptomatic onions to three onion cvs. New Mex Mesa, New Mex Vado, and New Mex Cryspy in growth chamber tests. All three cultivars showed symptoms of IYSV and tested positive for the disease using ELISA. However, New Mex Vado and New Mex Cryspy cultivars each showed 24% infection (4 infected plants of 17 tested) compared with 59% infection (10 infected plants of 17 tested) for New Mex Mesa, suggesting that not all cultivars are equally susceptible to the virus. To our knowledge, this is the first report of IYSV in onions in New Mexico, which has also been reported in the western United States in Idaho, Oregon, Colorado, and Washington (1,2,4). References: (1) L. J. du Toit et al. Plant Dis. 88:222, 2004. (2) J. M. Hall et al. Plant Dis. 77:952, 1993. (3) National Agricultural Statistics Service, On-line publication. USDA, 2004. (4) H. F. Schwartz et al. Plant Dis. 86:560, 2002.

Plant Viruses Transmitted by Thrips

“…A 'scape blight' of onion first reported in the USA in 1993 (Hall et al, 1993) is also now known to be caused by IYSV (Mohan and Moyer, 2002;Schwartz et al, 2002;du Toit et al, 2003;Creamer et al, 2004;Gent et al, 2004). IYSV has also been detected in onion in Slovenia (Mavric and Ravnikar, 2001), Australia (Coutts et al, 2003) and Japan .…”

Evaluating Winter-sown Onion Entries for Iris yellow spot virus Susceptibility

“…Since 2001, IYSV has been confirmed in all onion-producing states in the western United States, including Arizona, California, Colorado, Idaho, New Mexico, Nevada, Oregon, Utah, and Washington (Creamer et al, 2004;Crowe and Pappu, 2005;du Toit et al, 2004a;Hall et al, 1993;Pappu and Matheron, 2008;Poole et al, 2007;Schwartz et al, 2002) as well as in Georgia (Mullis et al, 2004), Texas (Miller et al, 2006), and New York (Hoepting et al, 2007). An IYSV epidemic in Colorado during 2003 is estimated to have cost growers $2.5 to $5.0 million in farm receipts alone (Schwartz and Gent, unpublished data).…”

“…IYSV incidence ranged from 58% to 97% among different cultivars. Creamer et al (2004) reported differences in the IYSV incidence of three onion cultivars in growth chamber tests. The objectives of this study were to screen onion germplasm for IYSV tolerance/resistance in terms of disease severity and incidence to determine the correlation between severity ratings and a measure of virus titer in the plant and to determine the relationship of plant sampling for rating selection with mean plot severity.…”

Temporal Dynamics of Iris Yellow Spot Virus and Its Vector,Thrips tabaci(Thysanoptera: Thripidae), in Seeded and Transplanted Onion Fields

“…Since 2000, IYSV has been conÞrmed in most onion production areas in the United States (Hall et al 1993, Schwartz et al 2002, Creamer et al 2004, du Toit et al 2004a, Mullis et al 2004, Crowe and Pappu 2005, Miller et al 2006, Pappu and Matheron 2008 and provinces in Canada . In New York, IYSV was Þrst detected in 2006 .…”