The origins of "spud" has erroneously been attributed to a 19th century activist group dedicated to keeping the potato out of Britain, calling itself The Society for the Prevention of an Unwholesome Diet.
It was Mario Pei's 1949 The Story of Language that can be blamed for the false origin of the word. Pei writes, "the potato, for its part, was in disrepute some centuries ago. Some Englishmen who did not fancy potatoes formed a Society for the Prevention of Unwholesome Diet. The initials of the main words in this title gave rise to spud." Like many other pre-20th century acronymic origins, this one is false.
The first edition of the Encyclopædia Britannica (1768-71), originally published in Edinburgh in the 18th century, referred to the potato as a "demoralizing esculent."