Phytopthora infestans, the suspect behind irish famine

Late blight caused by Phytopthora infestans is the disease that triggered the Irish potato famine in the 1840s. It also was the first plant disease for which a microorganism was proved to be the causal agent, leading to the birth of plant pathology as a science. Potato crops failed for a number of years during the cool and rainy "hungry '40s." Although poor people who were dependent on potatoes for food suffered in many areas, the disaster was greatest in Ireland. One and one-half million people starved and a similar number emigrated during the famine, resulting in a large Irish diaspora in many parts of North America. As with many famines, politics enhanced the suffering. Many Irish peasants grew cereal crops to pay their rent. Although the grain was harvested, it could not be eaten, and was exported to the English landlords throughout the famine.

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