Throughout the Potato Famine, from 1845 to 1947, more than one million people died of starvation or emigrated. Additionally, over 50,000 people died of diseases: typhus, scurvy, dysentery.
Despite the famine conditions, taxes, rents, and food exports were collected in excess of £6 million and sent to British landlords
Although the blight infected crops in the United States, Canada and Europe in the years of 1845-1846, the overpopulated subsistence farmers of Ireland were forced to export corn, wheat, barley, and oats to Britain, which left the potato as the sole dietary staple for people and animals.
The "white" potato, known today as the Irish potato, originated in the Andean Mountains in Peru. The Spanish brought the potato to Europe in the second half of the 16th century. Potatoes were considered a novelty and became fashionable in the mid-eighteenth century when Marie Antoinette wore potato blossoms in her hair.
During the eighteenth century, the kings of Europe discovered the nutritional value of the potato and ordered it planted. By 1800, the potato was everywhere and ninety percent of the Irish population was dependent on the potato as their main food.
Potatoes contain protein, carbohydrate, and vitamin C, which are necessary for a healthy diet, but lack vitamin A and calcium. Combined with milk, potatoes supply almost all food elements required for a healthy diet. To fulfil the daily nutritive requirement in the mid-1800s, each person had to eat 3 kilograms (six and a half pounds) of potatoes. According to historical accounts, a "burley farmer could down 15 potatoes" at one meal.
From 1816 onward, wet weather destroyed crops, the potato failed in several provinces and, weakened by hunger more than 100, 000 Irish died of starvation and disease. According to one farmer, in late September of 1845 a "queer mist came over the Irish Sea. . .and the potato stalks turned black as soot." The next day, the potatoes were "a wide waste of putrefaction giving off an offensive odour that could be smelled for miles." The potato blight (photophthora infestans), which caused the Great Famine of Ireland, results from an "airborne pathogen" that spreads rapidly among crops during warm and wet weather conditions. The disease attacks not only the crops in the field, but the crops in storage during a mild and damp period.
In 1845, the potato blight destroyed 40% of the Irish potatoes and the following year, approximately 100% of the crop was ruined. Successive crop failure led to 1847 being called "Black '47," with increases in famine, emigration, and disease. Although the potato crops from 1847-1851 were unaffected by the blight, famine conditions got worse due to a lack of seed potatoes for planting new crops and an inadequate amount of potatoes having been planted for fear that the blight would come back.