late blight

noun Plant Pathology.

1. a disease of plants, especially potatoes, celery, etc., characterized by spotting, blighting, and withering or decay of the entire plant, caused by any of several fungi, as Phytophthora infestans or Septoria apii.

1. A disease of potato plants caused by the oomycete organism Phytophthora infestans and characterized by decay of the foliage and tubers. An outbreak of late blight led to widespread famine in Ireland in 1845-1850.