Emerging viral disease caused by ToBRFV

Country focus: Emerging viral diseases in France

Tomatoes and cucurbits are under threat by emerging viral diseases caused by TYLCV, ToLCNDV and ToBRFV. The horticulture sector is rising up to the challenge to address this threat. Our “country focus” series highlights the situation in VIRTIGATION’s focus countries. Our fourth edition covers France, which is Europe’s largest agricultural producer.

TYLCV and ToLCNDV currently present

Tomato and cucurbits greenhouse production takes place throughout France. The main growing regions are the south east, south west and the Loire Valley. Tomato yellow leaf curl virus (TYLCV) is currently the main whitefly-transmitted virus affecting horticultural crops. TYLCV is sporadically present in greenhouse tomatoes in the south west near the Spanish border, as well as occasionally in the south east. It first appeared in the 2000’s in southern France, and was originally responsible for important problems on greenhouse tomatoes in the south west.

The tomato leaf curl New Delhi virus was not really present in the country for a long time. France observed TolCNDV on zucchini in the south east in fall 2020, but did not detect it again in 2021. However, in September 2022, local plant health authorities in the south of France (Bouches -du-Rhône) detected ToLCNDV on zucchini and melon in four sites (greenhouses and open fields). Local plant health authorities and VIRTIGATION partner INRAE have alerted national plant health authorities on this important finding. It is especially important monitor the ToLCNDV situation in the greenhouses in the south of France, where conditions are more favourable for the whitefly insect vector Bemisia tabaci. The climatic conditions in France outside greenhouses are not very favourable so far for Bemisia tabaci

As concerns ToBRFV, the European and Mediterranean Plant Protection Organization (EPPO) consider the virus to be transient and under eradication. French plant health authorities detected the virus in two instances in greenhouse tomatoes so far. Firstly, in February 2020 in the Brittany region, and secondly, in July 2021 in the south west. The country has carried out official ToBRFV monitoring plans since 2020 on tomato, pepper and eggplant crops, as well as tomato and pepper seeds. Seed monitoring of ToBRFV is crucial due to its seed transmissibility, and to prevent problems for seed exchanges.     

Tomato leaves affected by TYLCV
Example of tomato leaf damaged with TYLCV (© D. Blanchard, INRAE)

Measures taken to halt viral spread

French plant health authorities have used a mix of measures to contain the spread of TYLCV, as well as ToLCNDV and ToBRFV. In the cases of ToLCNDV and ToBRFV infection in 2020 and 2021, plant health authorities destroyed all infected crops. Regarding TYLCV, at the beginning French authorities removed the infected plants from affected greenhouses, and now the producers do it themselves.   

France has effectively contained ToBRFV through a series of prophylaxis measures associated with tobamoviruses. This includes greenhouse and material disinfection, seed disinfection, laboratory seed control and official crop surveys. As concerns ToLCNDV, the country has engaged in whitefly control, control of plant importations and official surveys to keep the virus in check. France addresses TYLCV through control of nurseries, use of tolerant/resistant cultivars as well as whitefly control. Overall, the viruses have affected tomatoes more than cucurbits, but the agronomic impact on the French horticultural sector has been limited so far

Crucial role of VIRTIGATION partner INRAE in virus fight

In France, the VIRTIGATION partner INRAE is the National Knowledge Broker for the country’s multi-actor approach in the project. INRAE and the French Agency for Food, Environmental and Occupational Health & Safety (Anses) were responsible for the first detection of ToLCNDV on French territory. It plays a crucial role in supporting growers with diagnostics. In addition to this, it also advises key stakeholders such as agricultural extension services, seed companies and farm advisors on measures to take to halt virus spread.     

INRAE is furthermore involved as key player in official national working groups, such as the risk analysis group for Anses. Moreover, INRAE is taking part in relevant working groups in all French regions. It also regularly engages with growers through meetings and dissemination activities (e.g. workshops, webinars). 

Building a strong knowledge base on emerging viruses

VIRTIGATION partner INRAE has also played an important role in updating the knowledge on tomato, cucurbit and pepper viruses impacting these crops in southern France. INRAE was part of the EU ERA-Net (Networking the European Research Area) project EMERAMB in this regard. EMERAMB researched in 2016-2019 emergent viruses and virus vectors in Mediterranean basin crops. The project searched for potentially emerging viruses or variants, including ToLCNDV and ToBRFV, which were not present at that time in France. In EMERAMB, INRAE was involved in the risk analyses developed for ToLCNDV and ToBRFV at the national and European levels. These findings constitute a key knowledge base to build on in tackling ToLCNDV and ToBRFV.