Curly Top Survey in the Western United States

Abstract

Curly top in sugar beet continues to be a challenging disease to control in the western United States. To aid in development of host resistance and management options, the curtovirus species composition was investigated by sampling 246 commercial fields along with nursery and field trials in the western United States. DNA was isolated from leaf samples and the species were identified using species-specific polymerase chain reaction primers for the C1 gene. Amplicons from 79 isolates were also sequenced to confirm identifications. Beet severe curly top virus (BSCTV) and Beet mild curly top virus (BMCTV) were widely distributed throughout the western United States, while only a few isolates of Beet curly top virus (BCTV) were found. In phylogenetic analysis, BSCTV, BMCTV, and BCTV isolates formed distinct groups in the dendrogram. Seven isolates not amplifiable with species-specific primers did amplify with curly top coat protein primers, indicating novel curtovirus species or strains may be present. Given the wide host range of the viruses responsible for curly top, frequent co-infections, and genetic diversity within and among species, establishing better host resistance, and controlling curly top will continue to be a challenge.

Control of Curly Top in Sugar Beet with Seed and Foliar Insecticides

“…In 2012 and 2013, 6 and 10 plants, respectively, were arbitrarily selected and sampled in mid-July to determine the species present in the trial. DNA extraction and polymerase chain reaction (PCR) were conducted with primers BSCTV-C1 2315F, BSCTV-C1 2740R, BMCTV-C1 2213F, BMCTV-C1 2609R, BCTV-C1 2097F, and BCTV-C1 2387R as described previously (29). Amplification products were electrophoresed through agarose gels (2% wt/vol) supplemented with ethidium bromide (0.0002 mg/ml) in Tris-borate-EDTA buffer (89 mM Tris base, 89 mM boric acid, and 2 mM EDTA).…”

“…Amplification products were electrophoresed through agarose gels (2% wt/vol) supplemented with ethidium bromide (0.0002 mg/ml) in Tris-borate-EDTA buffer (89 mM Tris base, 89 mM boric acid, and 2 mM EDTA). DNA from CTS07-11ID (contains BCTV, BMCTV, and BSCTV) served as a positive control (29). Reactions without template DNA served as negative controls.…”

“…In the western United States, curly top in sugar beet can be attributed to any of three Curtovirus spp.-Beet severe curly top virus (BSCTV; formerly strain CFH), Beet mild curly top virus (BMCTV; formerly strain Worland), and Beet curly top virus (BCTV; formerly strain Cal/Logan)-although sugar beet production areas outside the United States have been shown to possess additional strains or species (8,22,29,33). Finding more than one of these three species in a commercial sugar beet plant is not unusual (29). Recent taxonomic revisions released by the International Committee on Taxonomy of Viruses (second version 25 March 2013) places the three species mentioned above under the species name BCTV (13).…”

Evaluation of Beta corolliflora for Resistance to Curly Top in Idaho

“…The two elutions were not mixed and the second elution was used for PCR. PCR primers for differential detection of curtovirus species BSCTV (formerly CFH strain), Beet mild curly top virus (BMCTV; formerly Worland strain) and Beet curly top virus (BCTV; formerly Cal/Logan strain) were obtained from William Wintermantel, USDA-Agricultural Research Service, Salinas, CA (Strausbaugh et al, 2008). Positive virus control samples for BSCTV and BMCTV were obtained by extracting DNA from plants infected with well characterized species maintained by W. Wintermantel, USDA-ARS, Salinas, CA.…”

“…T he sugarbeet crop in the western United States has been afflicted with curly top (caused by Beet severe curly top virus (BSCTV) or closely related curtovirus species (Stenger, 1998;Strausbaugh et al, 2008)) since severe losses first were noted in Utah and California in the late 1890s (Bennett, 1971). Initially, this disease threatened to destroy the sugarbeet industry in the west.…”