potato blight

Disease of the potato caused by a parasitic fungus Phytophthora infestans. It was the cause of the 1845 potato famine in Ireland. New strains of P. infestans continue to arise. The most virulent version so far is P. infestans US-8, which arose in Mexico in 1992 , spreading to North America in 1994.

In 2000, US scientists managed to extract and sequence fungal DNA from dried potato leaves that had been kept preserved since the Irish potato famine. This will enable them to track how the fungus has evolved since then.