Apparently, kaffir lime trees tend to carry a plant disease called “greening”, which destroys other citrus trees, like oranges, lemons etc. That’s why agricultural authorities in different countries, including certain states in the US (Mostly citrus growing states like Florida) forbid growing kaffir lime. In those states, authorities use trained dogs to find the forbidden plants, and they’re destroyed (the plants, not the dogs 🙂 after samples are taken to the lab.
Just in case you were wondering, our kaffir lime essential oil is bacteria free (see GC-MS analysis) and poses no threat to the environment.
See more about the subject here (PDF).