Spatial associations of vines infected with grapevine red blotch virus in Oregon vineyards

Authors: DALTON, DALTON - Oregon State University; HILTON, RICHARD - Oregon State University; KAISER, C - Oregon State University; DAANE, KENT - University Of California; Sudarshana, Mysore; Vo, Julia; ZALOM, FRANK - University Of California; BUSER, JESSICA - Oregon State University; WALTON, VAUGHN - Oregon State University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2018
Publication Date: 4/25/2019
Citation: Dalton, D.T., Hilton, R.J., Kaiser, C., Daane, K.M., Sudarshana, M.R., Vo, J., Zalom, F., Buser, J.Z., Walton, V.M. 2019. Spatial associations of vines infected with grapevine red blotch virus in Oregon vineyards. Plant Disease. 103(7):1507-1514. https://doi.org/10.1094/PDIS-08-18-1306-RE.
DOI: https://doi.org/10.1094/PDIS-08-18-1306-RE

Interpretive Summary: Spread and in-field spatial patterns of Grapevine red blotch virus (GRBV) were documented in Oregon vineyards using field sampling, molecular diagnostics, and spatial analysis techniques. Grapevine leaf petiole tissues collected from 2013-2016 were tested using quantitative real-time PCR for GRBV. In southern Oregon, 3.1% of vines near Jacksonville were infected with GRBV in 2014, and the infection rate reached 58.5% of study vines by 2016. At Jacksonville, virus-infected plants were spatially aggregated in 2015, and diseased plants were associated between years 2014 to 2015, and years 2015 to 2016. In a vineyard near Talent, 10.0% of vines were infected with GRBV in 2014, and they increased to 21.5% in 2016. At Talent, aggregation was spatially associated across all years. GRBV infection was highest at Yamhill, in the Willamette Valley, where 30.7% of the tested vines had GRBV infection in 2014, and by 2016 59.2% of the vines tested positive for the virus. Areas of aggregation increased and were spatially associated across all years. During the same time period, GRBV was not detected at Milton-Freewater in eastern Oregon. Spatial patterns of GRBV infection support evidence of spread by a mobile insect vector, and spread appears to start at from vineyard edges. These data indicate that GRBV is a significant threat to Oregon winegrape production and provide a clearer understanding of the epidemiology of GRBV.

Technical Abstract: Spread and in-field spatial patterns of vines infected with grapevine red blotch virus (GRBV) were documented in Oregon vineyards using field sampling, molecular diagnostics, and spatial analysis. Grapevine petiole tissue collected from 2013 to 2016 was tested using quantitative polymerase chain reaction for GRBV. At Jacksonville in southern Oregon, 3.1% of vines were infected with GRBV in 2014, and GRBV incidence reached 58.5% of study vines by 2016. GRBV-infected plants and GRBVuninfected plantswere spatially aggregated at this site in 2015, and infected plants were spatially associated between years 2015 and 2016. In a southern Oregon vineyard near Talent, 10.4% of vines were infected with GRBV in 2014, and infection increased annually to 21.5%in 2016. At Talent, distribution of the infected vines was spatially associated across all years. GRBV infection was highest at Yamhill, in the Willamette Valley, where 31.7% of the tested vines had GRBV infection in 2014. By 2016, 59.2% of the vines tested positive for GRBV. Areas of aggregation increased and were spatially associated across all years. From 2013 to 2015, GRBV was not detected at Milton-Freewater in eastern Oregon. Spatial patterns of GRBV infection support evidence of spread by a mobile insect vector. GRBV is a significant threat to Oregon wine grape production because of its drastic year-over-year spread in affected vineyards.