P-510 - Zonal roguing as a new management response to a viral disease in the vineyard

Tuesday, August 5, 2025

10:15 AM - 11:00 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

MF

Madison Flasco, PhD

Assistant Professor
Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center
Baton Rouge, Louisiana, United States

Author(s)

DH

Daniel Heck

Plant Pathology and Plant-Microbe Biology, Cornell University, Long Island Horticultural Research and Extension Center
GENEVA, New York, United States
EC

Elizabeth Cieniewicz, PhD

Assistant Professor
Plant and Environmental Sciences, Clemson University
Clemson, South Carolina, United States
MC

Monica Cooper

University of California Cooperative Extension, University of California
Napa, California, United States
MF

Marc Fuchs

Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University
Geneva, New York, United States
SP

Sarah Jane Pethybridge

Plant Pathology & Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University
Geneva, New York, United States

Abstract Text: Red blotch disease, a threat to the grape industry, is caused by grapevine red blotch virus (GRBV). The dissemination of infected planting material has resulted in the widespread presence of the virus across the United States. Secondary spread has also been observed in northern California and southern Oregon vineyards. In northern California vineyards, secondary spread is attributed to the treehopper vector, Spissistilus festinus. Epidemiological studies in a California vineyard over the course of a decade revealed an increase in disease incidence from 3.9% in 2014 to 36.4% in 2023 with more rapid spread proximal to a disease focus. Disease spread dynamics was shaped by virus incidence, aggregation patterns, vector dispersal and weather conditions. Notably, an inverse correlation between disease incidence and rainfall events was observed with a 3-year lag; spread was slower three years after lower-than-average spring and summer rainfall. This lag time is consistent with an extended latency period of GRBV. It also suggested higher S. festinus populations outside vineyards, potentially due to flourishing preferred feeding and reproductive hosts in natural and riparian habitats. Join-count analysis suggested zonal rather than conventional roguing as an appropriate response to reduce virus incidence in some vineyard areas, given a high occurrence of asymptomatic infections. This is the first suggestion of zonal roguing, the removal of diseased and surrounding vines, regardless if they display disease symptoms or not, in response to a viral disease in a perennial fruit crop.