Described for the first time in India on tomato plans, the ToLCNDV virus is currently present in several European countries (Spain, Portugal, Italy, Greece, Estonia), where it causes damage to zucchini, cucumber and melon crops. Reported in France by professionals, the presence of ToLCNDV has just been confirmed following analyzes by ANSES in four zucchini production areas, in the Occitanie and Provence-Alpes-Côte-d’Azur regions.
Dissemination favored by the presence of a very effective vector
From the Geminiviridae family, the virus is transmitted mainly by a whitefly, the whitefly Bemisia tabaci, an insect vector considered to be very effective in spreading the disease. This vector insect acquires the virus in 15 to 30 minutes when it punctures the sap of infected plants. It then retains the virus for life and can thus disseminate it for several days by infecting healthy plants.
Considering the situation of the countries where it was detected, the virus is likely to infect a very large number of plant species such as potato, tomato, courgette, eggplant, melon, cucumber, pepper, squash, causing significant damage to crops. On zucchini, the plants are stunted, chlorotic. The leaves are deformed, rolled up and present more or less marked mosaics.
As with all plant viruses, there is no known way to cure an infected plant. To avoid its spread, prevention is therefore essential with the use of plant material or healthy plants, the elimination of diseased plants and the control of vector insect populations.
The Plant Health Laboratory, national reference laboratory
The ToLCNDV virus is a quarantine pest and is therefore regulated at European level. In France, the ANSES plant health laboratory carries out official analyzes to confirm its presence. A method allowing to identify viruses of the same family is used initially then, in the event of a positive result, the analysis of the specific genetic sequence of ToLCNDV is necessary to finalize the diagnosis. In order to strengthen virus detection capabilities, ANSES is also experimenting with several real-time PCR detection tests and participating in an inter-laboratory trial organized at European level by the European Union reference laboratory.
In February 2020, ANSES warned of a new emerging virus that is particularly dangerous for tomatoes. This virus, ToBRFV, is transmitted by infected seeds, plants and fruits, as well as by simple contact and can survive for a long time without losing its infectivity. Although it was detected in February 2020 in the Brittany region, no new outbreak has since been identified. The measures taken in Europe have led to the strengthening of surveillance of the virus on national territory, carried out by State services and their delegates, which has made it possible to limit its spread.
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