The potato crop in Ireland failed in three years out of four:  1845, 1846, 1848.
The cause was the potato blight or Phytophthora infestans, a fungal disease.
About one million people or 12% of the population died of starvation or disease.
Another one million emigrated from Ireland.

It is now known that this strange potato blight struck in the USA in 1843 and 1844 and in Canada in 1844. It is thought that the disease travelled to Europe on trade ships and spread to England and finally to Ireland, striking the south-east first.

In September 1845 the fungal disease struck the potatoes as they grew in fields across Ireland. Many of the potatoes were found to have gone black and rotten and their leaves had withered.
In the harvest of 1845, between one-third and half of the potato crop was destroyed by the strange disease, which became known as 'potato blight'. It was not possible to eat the blighted potatoes, and the rest of 1845 was a period of hardship, although not starvation, for those who depended on it.
The price of potatoes more than doubled over the winter: a hundredweight [50kg] of potatoes rose in price from 16p to 36p.

In the years after the famine, scientists discovered that the blight was, in fact, caused by a fungus, and they managed to isolate it.

They named it Phytophthora Infestans. 

However it was not until 1882, almost 40 years after the famine, that scientists discovered a cure for Phytophthora Infestans: a solution of copper sulphate sprayed before the fungus had gained root. At the time of the famine there was nothing that farmers could do to save their crop.

Use the links to discover more about the famine....