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1.1.1.c Are the plots healthy?

Is the plot contaminated by viruses?

The principal culprit, as well as the most problematic, is the Grapevine fanleaf virus (GFLV). This virus is transmitted by nematodes whom develop at considerable depth making them impossible to eradicate. Therefore, the virus is cumulative. When it appears, it continues to contaminate neighboring plants in the plot without any measures to prevent its progression.
Infected plants are ill-fated as well as any select young plants replanted on the plot, they will subsequently contaminated as well.
Therefore, select replanting of missing vines is not the best option.

Grapevine fanleaf virus symptoms at Domaine d'Eugénie

Since the phylloxera crisis there has been a corresponding simultaneous increase in GFLV cases. This is considered the most important viticultural virus both in terms of its dissemination throughout the world's vineyards and its subsequent impact on the wine industry.
The only proven effective way to rid a vineyard of this virus is soil rest following grubbing up coupled with a nematicidal plant cover. This virus is therefore a key factor when choosing to grub up a plot.

Is the plot contaminated by wood diseases?

Three types of wood disease are of note: Esca, BDA and Eutypiosis. The three diseases are all caused by fungi.
These diseases become increasingly prevalent as a plot ages, as large pruning wounds and the appearance of dead wood are considered to be the major entry point for these diseases. Certain grape varieties are more suseptible than others. Cabernet-Sauvignon and Sauvignon Blanc are most susceptible to Esca. Ugni blanc is more vulnerable to Eutypiosis.

ESCA-contaminated wood from this Cabernet-Sauvignon vine has been scraped out

A severely contaminated plot will most likely have to be uprooted due to the number of non-productive plants. Currently, the only way to manage these contaminants are with prophylaxis measures (Wood disease and virus management).

Another notable disease is root rot. Often found when plots have water drainage problems or are located near oak trees. Preventive measures in these instances are key. On an affected plot, it is often best to uproot and set up a drainage system if necessary or eliminate any oak trees in the vicinity.

Is the plot contaminated by yellow phytoplasmas?

Two diseases are elaborated here: Grapevine Flavescence Dorée and Bois noir. Each have identical symptoms and can only be differentiated using genetic analysis.

Flavescence Dorée is a phytoplasma jaundice transmitted by an insect: the leafhopper called Scaphoideus titanus. When prevalent in a region it can mean that one or more compulsory insecticide treatments to mitigate propagation is recommended. Moreover, if contamination remains high (more than 20%), pulling up the plot becomes compulsory. It is therefore crucial to keep tabs on this figure when organising an uprooting calander. That said, in most cases the risk is managed through rigorous surveillance of the zone, systematic uprooting of any diseased vines and closely monitoring the application of compulsory treatments.

Bois Noir is transmitted by the leafhopper Hyalesthes obsoletus. Given that this leafhopper does not reproduce on vines but on various surrounding plants, an insecticide treatment is impossible. The only possible biocontrol measures would involve eliminating nearby host plants such as nettles, bindweed, etc. The removal of infected vines is the only possibility and this is a compulsory measure in some regions.

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