I need to clean and restore an old olive plantation which was not cultivated for around 20 years and is now covered with weeds, bushes and spruce tree. I'm new to olive trees but have clean almost everything. But one "pest" bothers and comes back very quickly. It is a plant Smilax aspera which so far I was unable to eradicate. It grows very quickly and is capable to cover and suffocate whole olive tree.
What is the best way to get rid of Smilax aspera?
Initially I thought to do everything in an ecological way, but now this Smilax aspera is very resistant and I'm comfortable to use chemicals. Reason (frustration) for this is that olive plantation is far from road access, 1200 m (6000 ft) on very difficult to walk Mediterranean rocky terrain and even when Smilax aspera is removed from under the olive trees, it grows from nearby dry walls as on this image:
What other options do I have? Would burning and use of fire remove it permanently?