FROM DETECTION TO PREVENTION: PREVALENCE OF REGULATED NON QUARANTINE VIRUSES IN BELGIAN VINEYARDS

Belgian viticulture has expanded rapidly over the last decade, now approaching 1,000 hectares and
establishing a new grape-growing region in northern Europe. While this development offers major economic
opportunities, it also increases exposure to phytosanitary risks, particularly viral diseases introduced
through infected planting material or through local transmission within vineyards. For emerging cropping
systems, understanding virus prevalence and epidemiological patterns is essential to design effective
prevention and crop protection strategies.
Within the framework of the VITIBEL project, large-scale surveys conducted in 2023–2024 combined high
throughput sequencing (HTS) with targeted molecular diagnostics to establish the first national inventory of
grapevine viruses and viroids in Belgium. These surveys revealed the first detection in the country of five
European Union regulated non-quarantine pests (RNQPs): Nepovirus foliumflabelli (GFLV), Ampelovirus
univitis (GLRaV-1), Ampelovirus trivitis (GLRaV-3), Nepovirus arabis (ArMV) and Nepovirus rubi (RpRSV).
While HTS provides broad detection capabilities, its current cost and throughput limit its use for large-scale
field prevalence studies. Consequently, quantitative assessment of virus prevalence and spatial patterns at
the vineyard level relies on targeted diagnostic assays that are better suited for systematic field surveys.
To address this gap, prevalence studies were initiated in 2025 in vineyards where RNQPs had previously
been detected. The study covers 15 commercial vineyards and three grapevine collection centres,
encompassing 20 plots representing approximately 23,000 vines. A statistically based sampling design was
implemented to estimate within-parcel virus prevalence while accounting for vineyard size and structure.
Systematic spatial sampling was conducted across approximately 4,800 vines, with samples pooled in groups
of five and analysed using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA).
Positive pools were subsequently resolved at the individual vine level.
GFLV was selected for a more detailed investigation. In three vineyards, targeted sampling around
symptomatic vines was combined with soil analyses for nematode vector detection, enabling exploration of
potential local transmission processes and supporting management-oriented interpretations.
Ongoing analyses are expected to reveal contrasting epidemiological situations among RNQPs and
vineyards, ranging from isolated introductions to more widespread infections. The final results are
anticipated to provide the first quantitative estimates of RNQP virus prevalence in Belgian viticulture and to
identify key factors relevant for disease prevention, including early detection, monitoring strategies, and the
respective roles of planting material and local spread. By moving from virus detection to prevalence-based
risk assessment, this work aims to support the development of proactive crop protection strategies adapted
to newly established viticultural regions.