I was reading an article in the November COPA Flight - written by Adam Hunt which was educating and encouraging pilots to report any sightings of marijuana growing in fields etc. I don't want to discourage reporting, however, it is important for pilots to exercise some caution when over-flying these fields. Sometimes the illicit growers are tending their plants, harvesting etc. and will take note of the aircraft registration on the underside of the wing - particularly if the aircraft keeps passing over (to record a GPS waypoint, take a photo, or just to get a better look).
Armed with that registration, it is a simple (for some anyways) exercise to visit the Transport Canada website and obtain the name and home address of the aircraft owner. It has happened on one occasion in my area where an over flight like this resulted in a "less than friendly" visit to the pilot from the "plantation owner" - or more likely someone hired by the plantation owner.
I understand that some of these folks will also intimidate/threaten the farmer on whose land the marijuana crops are being grown. Most often the farmers do know that marijuana is being grown on their land, they are just too scared to report it - as they have been severely threatened. These guys mean business - and as the article pointed out, it is a very big business.
Again, I do think we need to report this activity, but your average COPA pilot is not working for the RCMP or the OPP for example. Over-flying and reporting is entirely at the private pilot's own personal risk - and therefore some caution is in order. Here are some steps I exercise when doing this:
If we keep these precautions in mind, I'm sure the law enforcement folks will be happy to receive the information while at the same time protecting the pilot and his or her family.