Team:Toulouse/Project/project-context

One of Europe most famous scenic is without a doubt the Toulouse Canal du Midi. Situated in the heart of our city and going through Southern France, our lab is only 5 minutes walk from the Canal du Midi. Everyone in the team enjoys the quietness and loveliness of this charming place. Unfortunately, this heritage is threatened: a phytopathogenic fungus, Ceratocystis platani, is devastating the trees lining the Canal.

The situation is alarming: today the only solution is preventive tree cutting to stem the fungal epidemic. The consequences are disastrous. Not only for the beauty of the landscapes but it has also a huge environmental, social and economic costs. Today, 42,000 plane trees are threatened, knowing that cutting and planting a new resistant tree is about € 4,000.

The Canal du midi

This ingenious masterpiece respects the environment in which it is harmoniously integrated since 1681 by Pierre-Paul Riquet. Characterized as a summit level canal, it culminates at 189 meters of altitude and connects, from coast to coast the Atlantic and the Mediterranean seas. On December 7^th 1996, the UNESCO registers Le Canal du Midi on the list of world’s legacy. The first plane trees bordering the canal were planted after its creation in 1776. Resolving the erosion of riverbanks and the evaporation of the water, the plane imposed itself as a dominant and emblematic tree. The wooded legacy is estimated to about 42,000 trees, it contributes to the landscape and aesthetic. Today, the canal du midi is primarily used for tourism, recreation and housing. Busier than the Seine (Paris river), it accounts for one fifth of French river tourism and 80 % tourists are foreigners. Boaters seeking for tranquility, quietness and a unique environment mainly navigate over it.

Canker Stain

The canker stain is a disease caused by Ceratocystis platani, a microscopic fungus that exclusively attacks Plane Trees. Probably introduced in France by infected wooden munitions cases coming from United States of America in 1945, the fungus introduces itself inside the sain tree’s heart, blocks the sap flow and kills it in only 2 to 5 years. On the regulatory side, on July 31^th 2000 a ministerial order has classed Ceratocystis platani as an harmful organism for plants. This order leads to a mandatory fight against the fungus.

Fighting the plane trees pathogen

Regarding this imminent threat, some solutions emerged.
First of all, chemical fungicides were used. However, the community realized it was impossible to eradicate the whole fungus.
Therefore, the French Institut National de Recherche Agronomique (INRA) created a new type of plane trees named Platanor which were resistant to the fungus infection. Unfortunately, this extreme measure could not save the already contaminated trees nearby the Canal du Midi.
Today, the only option remains in the tree-cutting of the contaminated plane trees. Nevertheless, this previous solution is not optimal because of the high cost and the major touristic and social impact for our heritage.

References

• Photo VNF/Sud-Ouest

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