In 1694, the first trees were planted alongside the Canal du Midi. They were mainly willow trees and they were planted to stabilise the banks. As the years went by, other tree species were added because the shade they provided was much appreciated by users of the canal. Trees were chosen depending on what they could offer.
Therefore, in 1767, a planting initiative was launched, and mulberry trees (to breed silkworms) and the black poplar (for timber) dominated the banks of the Canal du Midi.
Pine trees, cypress and fruit trees were planted around lock keeper's houses. After 1775, the first plane trees started to appear.
In the 19th century, the Compagnie du Canal du Midi wanted to really make the most of the area along the canal banks and so they launched a large-scale planting initiative, focusing on three main tree species: elm, ash and plane trees.
The elm trees were destroyed by a disease and were progressively replaced by plane trees. These trees were not used for timber and so they increasingly covered the region. These majestic trees form a leafy canopy along the banks, and for over a century, they have been symbolic of the Canal du Midi.
Now it is the plane trees that are being attacked by a disease. Since 2006, these trees have been battling a microscopic fungus, Ceratocystis platani (canker stain of plane). This disease infects a healthy tree, blocks the sap channels and kills the tree in just 2 to 5 years.
The canal provides an environment where canker stain can develop rapidly. The water allows spores to be transported by the hulls of the boats, also boats hitting the roots or being moored directly to the trees may be forbidden but these acts are still allowing canker stain to spread. The disease can also spread from the roots of nearby trees. This is why the rows of plane trees along the canal are so vulnerable.
To eradicate this disease, the infected trees need to be felled and incinerated. Of the 45,000 trees along the Canal du Midi, 42,000 are plane trees. In 2023, close to 75% of the 42,000 plane trees on the banks of the Canal du Midi were cut down!
To restore the canopy, VNF launched a large-scale initiative to replant trees in 2011, with support from the Region and Departments. The time has come to diversify the tree species here and seven species have been selected. This will encourage biodiversity and prevent another disease from infecting so many trees in the future. The turkey oak is a hardy tree species and as high as a plane tree, so this was chosen as the canal's new iconic species. Rows of oak will alternate with sections of other tree species, also selected for their height (20-30 m) and their ability to adapt to the regions.
Did you know?
During the winter of 2022/2023, 1,350 new trees were planted, reaching a total of 18,000 trees planted since the winter of 2011-2012. Work must always be done to strengthen the banks before any new trees are planted. Over 3,000 trees are also regularly maintained to encourage their growth and to ensure they blend into the scenery here for years to come.