After tomato plants were taken back to Europe from the New World in the early 1500s, people in various places considered the fruit poisonous for the next two centuries. The reasoning behind the fear of tomatoes came from several sources:



1. Rich people ate tomatoes and then died. Their fancy pewter plates were later found to be the reason.



2. Scientists of the time classified the tomato as a deadly nightshade and a mandrake -both scary terms.



3. Tomato leaves smell awful, so one researcher pronounced the entire plant toxic.



4. Scary-looking worms infested tomato plants.



An article at Smithsonain's Food and Think blog explains each of these concerns, which lingered far into the 1800s, plus a bonus video containing a scene from Attack of the Killer Tomatoes. Link



(Image credit: Flickr user Kicki Holmén)