It took a widespread failure of grain crops in the late 18th century, and resulting famines in Germany, Ireland and Scotland for the importance of potatoes as a food crop to be recognised in northern Europe.

By the 19th century they had become a staple food, a factor in Europe's population boom. Blight, unknown when potatoes first arrived in Europe, now became a grave hazard.
No cure was known for the blight until potato-growers downwind from a copper-smelting plant in South Wales noticed that their crops were blight-free. 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. Since then 'Bordeaux mixture' (a spray of copper sulphate and lime) has been used to protect conventionally grown crops.
It is the height of tragedy that the cure for the blight was found by smelting ores in Swansea that were imported from numerous mines in West Cork and the Beara penninsula where the effects of the famine were perhaps the most extreme. Although by 1880 irish copper imports were in decline as new world mines such as butte took precedence.