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Team:EPFL/Description





















Background

Plant crops are constantly under attack from a variety of pests: bacteria, viruses, insects, fungi. But one of these has been at the forefront on the War on Pests recently: Phytoplasma.
Phytoplasma are a class of bacteria usually transmitted via an insect and has been linked with devastating damage to over 700 plant species worldwide. Phytoplasma-infected crops have been reported in 47 countries on 5 continents1.

Despite their economic impact, phytoplasma remain one of the most poorly characterized plant pathogens. Quick and reliable disease identification of infected plants is necessary to plan adequate strategies for its containment. When such information is not available, crops are lost and/or excessive amounts of pesticides are applied. This is very harmful to the environment, since over 98% of sprayed pesticides reach a destination other than their target species, including becoming pollutants of air, water, and soil2. Reducing pesticide consumption has been a key driving force in creating our novel diagnostic system. Furthermore, the available territory of the vectors responsible for spreading these diseases has increased due to favorable prevailing climate conditions. Thus, as global warming continues, these outbreaks will only grow in numbers.

Annual pesticide consumption per million kilograms - Top 10 countries 2

Our Problem

Winemaking is of great cultural importance in Switzerland. Not only is it home to some of the most beautiful vineyards in the world, some of which have become a UNESCO world heritage site, but also one of the most famous wine festivals in the world, the Fête des Vignerons. It is an iconic event, taking place only once every 25 years, and we were fortunate enough that this year the festival coincided with our iGEM project. The wine industry is also one of the most important agroindustries in the world, both economically and culturally. In 2018, wine production reached 29.2 billion liters worldwide, with 50% coming from Spain, France and Italy alone. The International Organisation of Vine and Wine (OIV) estimated the economic value of wine sale in 2018 to be 31 billion euros3.

Currently, European winegrowers are being confronted with two serious phytoplasma-borne diseases: Flavescence Dorée (FD) and Bois Noir (BN). The diseases are collectively known as Grapevine Yellows and express the exact same symptoms, making it impossible to differentiate them by eye.

Symptoms of Flavescence Dorée on Divico (Image A, Chardonne, 8/21/2019) and Chasselas (Images B and C, Chardonne, 9/12/2019)


Symptoms of Bois Noir on Divico (Chardonne, 9/19/2019)

Symptoms of Bois Noir and Flavescence dorée on Divico (Chardonne, 9/19/2019). While Bois Noir hasn't spread to the full leaf (left), the symptomatic areas of both leaves are strictly identical.



Flavescence Dorée is a highly-contagious, quarantined disease spreading rapidly over Europe via its vector, the insect Scaphoideus titanus. On the other hand, Bois Noir is hardly contagious and shows no risk for the vineyard as a whole. Laboratory testing is required to identify the disease in a symptomatic plant. Systematic control of the vineyards allowed to generate so-called "contamination zones", areas where Flavescence Dorée is known to occur, in which the winegrowers are required to use large quantities of pesticides to kill the vector. If a vine stock tests positive for Flavescence Dorée, it will be uprooted and burned to destroy the pathogen. If more than 20% of a field is infected, then all the vines from that field, infected or not, must be uprooted and burned. These methods have shown mixed results in terms of disease containment4, and the heavy use of pesticides is not sustainable from an ecological point of view.





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Cases doubled since 2016 in the Canton of Vaud
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Of vineyards under surveillance in France
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Vines infected with FD in Bordeaux in 2011
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Vineyards infected in the past 10 years in Switzerland

Status of Flavescence Dorée in Europe

Flavescence Dorée appeared in southern Europe more than 50 years ago and has gradually been spreading North. In 2017, 70% of French vineyards (557'650 ha) were inside the mandatory surveillance zone4. In the Canton of Vaud, Switzerland, the number of diagnostic tests for Flavescence Dorée has risen from 130 in 2016 to 433 in 2018, a 233% increase in 2 years5, 6. Besides France and Switzerland, FD has been reported in Italy, Spain, Portugal, Austria, Croatia, Hungary, Slovenia and Serbia7. In 2015, a 3-year initiative called WINETWORK was funded by the EU to improve collaboration between European countries on the subject of grapevine trunk diseases and FD8. They released a number of technical datasheets on the diseases and the methods to contain them, mostly directed at researchers and winegrowers, but also to increase public awareness of the epidemic.


Today’s Solution

For a test to be an official diagnostic method used by European farmers, it must fulfill the standards established by the European Mediterranean Plant Protection Organization (EPPO). In Switzerland, grapevine that are suspected to be infected are sampled by the phytosanitary police. Those samples are then sent to the Federal center for agricultural research, Agroscope, for pathogen identification. The nominal time between sampling and results is 3-15 days. In other European countries such as France however, this can take up to 8 weeks.


ViTest

Our goal is to produce a system that enables winegrowers to perform the test themselves in their fields, without lab equipment or specialized training. This will reduce the diagnostic time from several weeks to just a few hours, removing all problems related to delays in the disease identification process. Moreover, winegrowers will gain more knowledge and direct control over their vines. By immediately testing any symptomatic vine stock, they can decide early on to remove the infected plant, therefore significantly reducing the chance for the disease to spread.


Integrated Human Practices

As our project idea originated from discussions we had with winegrowers about Flavescence Dorée and Bois Noir, it was paramount for us to keep them, and other stakeholders, involved in the creation of our test. This would ensure that the test we set out to create would be useful and applicable in real-world conditions. To that end, we contacted the Swiss phytosanitary police to learn more about the current diagnostic methods for grapevine diseases and Agroscope, the Federal research center for agriculture, for technical advice on our test. We used their recommendations as well as winegrowers’ insight to fine tune our test in order to meet their needs.

References

1 Shweta Kumari, et al, 2019 Jun 27, Global Status of Phytoplasma Diseases in Vegetable Crops [link to article]

2 Top Pesticide Using Countries, April 25, 2017, [link to website]

3 OIV (International Organisation of Vine and Wine), 2019, 2019 Statistical Report on World Vitiviniculture, [link to article]

4 Groupement de Défense contre les Organismes Nuisibles (GDON), Bilan Flavescence Dorée 2017, [link to pdf]

5 Direction générale de l’agriculture, de la viticulture et des affaires vétérinaires, 2018, Rapport phytosanitaire 2018 – Organismes nuisibles réglementés

6 Département de l'économie et du sport, Service de l'agriculture et de la viticulture, 2016, Rapport phytosanitaire 2016 - Organismes nuisibles réglementés et autorisations spéciales

7 Jeger M. et al, 2016, Risk to plant health of Flavescence Doree for the EU territory, p. 13, [link to article]

8 http://www.winetwork.eu/