Agriculture and Farming Atlas
The Pathogen Behind a Famine
Most pages in this atlas describe Phytophthora infestans as a crop problem: lesions, yield loss, fungicide cost. This one asks a different question. When a single water mold triggers one of history's deadliest famines, how much of what follows belongs to the pathogen, and how much belongs to the people who governed the country it struck?
A crop disease, honestly described
Late blight is an oomycete, a water mold long grouped with fungi in agricultural practice, and it earns its ordinary agricultural framing honestly: it remains one of the costliest plant diseases in the world, with global management and loss costs estimated at several billion dollars a year, and it still attacks tomato as well as the potato that made it famous. But its single most consequential outbreak was not measured in yield. In the 1840s it destroyed the potato crop that Ireland's rural poor depended on, and the famine that followed, known also as the Great Famine, the Great Hunger and An Gorta Mor, ran from 1845 to 1852.
What is still argued
What the record does not settle is how much of the mass death and emigration that followed belongs to the pathogen itself, as against the response of the government that governed Ireland at the time. That question is still debated, and this atlas carries it as open rather than resolved. Late blight's own reach was never limited to the one crop that made it famous; it was the dependence of Ireland's rural poor on a single staple, not the pathogen's range, that turned an ordinary crop disease into a famine remembered by three different names.
Where To Read More
- Late BlightFungal Diseases of CropsSubject of the essay.
- Irish Potato FamineAgricultural Famines and DisastersThe Irish potato famine: the essay's own subject, cited here so a reader can move from the pathogen to the famine it fed and back.
- Phytophthora infestansFungal Diseases of CropsThe oomycete pathogen discussed by name.
- TomatoVegetables and MelonsTomato: cited because late blight's own attested relationship to this crop is what shows its reach was never limited to potato alone.