Potato blight is the so-called "fungal" disease which destroyed the Irish potatoes in 1845. Because there are other blights of potatoes, this one is sometimes called late blight of potato.

The infestation caused widespread famine. It was caused by an oomycete Phytophthora infestans. The oomycetes or water moulds have many features which are similar to fungi, but they are in a different Kingdom.