Exploring a new territory for grapevine viruses: first outputs from winemaker interviews and virome survey in Belgium

Belgian viticulture, driven by climate change and growing consumer interest, has expanded from 72 hectares in 2006 to 891 hectares in 2023. Despite lacking a long-established winemaking tradition, Belgium is creating new agroecosystems where winemakers explore diverse grape varieties and cultural techniques.
However, this expansion in new territories brings growing threats from viral and viroid pathogens. Key questions arise: Which viruses and viroids could potentially affect Belgian vineyards? Are they already present in our territory? How did they arrive? What is the readiness for outbreak management?
To address these concerns, we conducted a comprehensive study involving a questionnaire and interviews with winegrowers. The responses from 88 growers described the typology of grapevine cultivation in Belgium related to the cultural practices, the origin of planting material, the diversity of cultivars, the perception of viral and phytoplasma threat… This survey was complemented by an extensive virome survey: more than 7,000 plants (either symptomatic or not) from 50 grape varieties were sampled in 86 vineyards across Belgium. For asymptomatic samples, double-stranded RNA (dsRNA) extraction was performed, while total RNA extraction was conducted on symptomatic leaves. The RNA extracts were then sequenced and relevant virus detection confirmed by RT-PCR.
Analysis of symptomatic samples collected over the past two years identified 6 viruses and 4 viroids for the first time in Belgium, including Grapevine fanleaf virus (GFLV), all confirmed independently by RT-PCR. Asymptomatic samples analysis is ongoing.
Further investigations will explore potential links between the observed virome and the typology of vineyards, including plant origin and cultivar. Beyond scientific results on viruses, the interactions with growers during the virome survey is also raising awareness about the viral (and phytoplasma) risks. This research enhances our understanding of phytosanitary risks in Belgian viticulture and contributes to developing effective management strategies to safeguard this emerging industry.