Scientists have identified a unique strain of blight which they believe triggered Ireland's potato famine in the mid-19th century.
They have called the strain HERB-1.
The deadly famine has been linked to a fungal disease called potato blight, which came to Ireland from Mexico.
A team of molecular biologists from Europe and the US reconstructed the spread of the potato blight pathogen from dried plants.
Many of the materials, despite being between 120 to 170 years old, contained intact pieces of DNA, according to the details published in the journal eLife.