How did the Irish Potato Famine of the mid-1800s originate? I came upon one possible answer in an unlikely book: The Conquest of Nature: Water, Landscapes and the Making of Modern Germany, by David Blackbourn, 2006. He wrote:

 “One result of the greatly increased traffic across the world’s oceans was that we would now call ‘biological invasions.’ It was not just people, cotton and tobacco that crossed the Atlantic but other, less desireable  species also made these journeys as stowaways in cargo holds, ballast tanks or attached to the ship. The invasive species that created the most alarm in the newly unified Germany were two arrivals from North America… the vine disease phylloxera and the Colorado Beetle, both of which attacked potatoes.”

Wanting to know more, I turned to Google. Wikipedia stated: “it is assumed that winds spread the spores (of phytophthora infestans) that caused the widespread devastation of potato crops in Ireland and northern Europe beginning in 1845, leading to the Irish Potato Famine.” Also, ” The potato blight was found across the Eastern part of the U.S. and Canada and crossed the Atlantic in 1845, probably with a shipment of seed potatoes for Belgian farmers which ultimately spread to all the potato-growing countries in Europe.  

If you’d want to read more, Google to The History Place: Irish Potato Famine, the Blight Begins or Milestones in History: The Great Hunger, article by Eugene Finerman, 2009. 

This last article was subtitled: “Ireland’s potato famine was caused as much by a government’s gross negligence as by a devastation of crops.”