What crop did Ireland become dependent on?

The Irish Potato Famine, also known as the Great Famine, was a period of mass starvation, disease, and emigration in Ireland between 1845 and 1852. It was caused by a fungus called Phytophthora infestans, which affected potato crops throughout Europe, but had a particularly devastating impact on Ireland, where the potato was a staple food. Over one million people died and more than two million emigrated from the country.