In folk legends from the Balkans, in Southeastern Europe, there is such a thing as vampiric pumpkins (yes pumpkin) which would become possessed, grow to an excessive size and because of their lack of teeth wouldn’t bite you, but squash you to death instead. Honestly, you can’t make this up.
The story is associated with the Romani people of the region and were described by ethologist Tatomir Vukanovic. The Romani culture is steeped in supernatural lore and superstitions that both give and take from the many surrounding cultures that they cohabitate with. The Balkans, especially, has a large array of supernatural beliefs and superstitions, many of which include the dead and the undead.
Vampire stories vary greatly in different cultures, and so does the belief. If you try to put them all together, quite honestly, just about anything can be a sign or a cause for someone or something becoming a vampire. People who were particularly unfortunate looking could be vampires. People who were missing fingers, had extra fingers or had tails were considered vampires. Anne Boelyn, for example, was rumoured to be a “demon” because she was said to have an extra pinky – although this could be a smear campaign from Henry VIII’s camp who were trying to get rid of her. The neglect of performing the proper ritual after someone’s death could cause someone to become a vampire. People who died violently, committed suicide or died of a horrific accident could also become a vampire. Those who were excommunicated from the church could be a vampire. Children conceived on certain days or out of wedlock could become a vampire. Children born with teeth were believed to be vampires. And these are just some of the stories.
The only known reference in scholarship is Vukanović’s account from 1933 to 1948 which seems to be repeated in other sources, but I would be remiss if I don’t quote some of it: “According to them there are only two plants which are regarded as likely to turn into vampires: pumpkins of every kind and water-melons. And the change takes place when they are ‘fighting one another.’ …. In Podrima and Prizrenski Podgor they consider this transformation occurs if these ground fruit have been kept for more than ten days… It is also believed that sometimes a trace of blood can be seen on the pumpkin, and the Gs. then say it has become a vampire.”
The Journal of the Gypsy Lore Society has many articles that are collections of Romani tales, presumably oral history. From experience, I wouldn’t be quick to discount oral history as false, although references of their stories change wildly from one region to the next because no one set them down in paper, real or not they give us a window to people’s beliefs, and things that children would have grown up hearing. A lot of myth and legends of Southeast Asia, for example, were from oral history which accounts for the confusing variations of tales (if we’re lucky) or the virtually non-existent written sources. So in this context, I suppose vampire pumpkins and watermelons are not necessarily any more implausible than other superstitious beliefs. That is, of course, my “official” answer if anyone should ever ask whether I think this was true. My unofficial answer is “who cares? this is cool!”