The potato blight that swept over Ireland in the 1840’s was felt throughout Europe. Perhaps bad weather made the blight particularly damaging in Ireland. The disease is a fungus spread by the wind. The fungus lands on the leaves and rots the potato tuber itself in the ground. The tuber is useless for eating because it goes black, mushy, and smells.

The fungus “phytophthora infestans” probably started in South America, spread to North America in the early 1840’s, then to Ireland in 1845, 1846, 1848 and 1849. In 1845, about one third to one half of the Irish potato crop was diseased. This was a huge disaster because the food supply for approximately 30-40% of the Irish population was destroyed. About 3 million people were at risk from 1845 through to 1850 because of this disease.

Approximately 12% of the entire Irish population of 8.2 million people died during the Famine years. The huge drop in the food supply was not made up by imported food, and so people did not have enough to eat. While many died of starvation, malnourishment (lack of proper food) over the Famine years meant that diseases such as typhus and cholera were responsible for most of the deaths. From 1847-50 people had been weakened by years of malnourishment and bad living conditions.

The Famine did not destroy the potato crop evenly throughout the country. The effects of the blight varied from place to place and year to year. Some areas faced hunger but not the starvation that faced other areas. In this environmental disaster, Leinster County lost 15% of its population to death and emigration, Ulster lost 16%, and Connaught lost 28.6%.

A second environmental problem Ireland faced was overpopulation. Ireland was reputed (thought) to be the most densely populated country in Europe at the time, but it was a rural not an urban-industrial society. Some challenged that view and asserted that Ireland could have supported its 8.2 million people had proper economic and political structures been in place.