Early mapping of potato blight in the United States provides insight into the disease's initial spread, as well as contemporary theories about its cause and treatment before its introduction to Europe.A study published February 15 in the journal Scientific Reports is the first to accurately depict the outbreak of potato blight (a disease caused by the fungal pathogen Phytophthorainfestans) in the United States from 1843 to 1845. These findings add to our understanding of the spread of potato blight before it was introduced into Europe.

Tracking the Pathogen’s Journey

JeanRistaino and colleagues mapped potato blight outbreaks in North America between 1843 and 1845 by analyzing historical agricultural reports published in the United States during this period.

The researchers found that the disease was first reported in 1843 in five locations in New York, Pennsylvania, New Jersey, Delaware and Connecticut. By the end of 1844, the disease had spread to 107 locations, six additional U.S. states (Ohio, Massachusetts, Rhode Island, Vermont, New Hampshire, and Maine) and the Canadian province of Nova Scotia.

In 1845, the disease spread to 53 new places, including four more states in the United States (Michigan, Illinois, Indiana, Maryland) and the Canadian province of New Brunswick. Contemporary reports indicate that the disease caused crop losses of 33% to 50%.


Late blight lesions on potato leaves. Source: Jean Ristaino, North Carolina State University

The researchers also used their method to describe historical theories about the origin and treatment of potato blight from 1843 to 1845. Suggested causes during this period included insects, climatic conditions, inferior potato varieties and fungi.

In addition, scientists found widespread debate among reports about whether the fungus was the cause or effect. Suggested treatments for the disease include calcium oxide (called lime), sulfur, copper sulfate (called bluestone copper), and salt. Infected imported potato seed cubes from places such as Nova Scotia, France, and Bogotá, Colombia, are suspected to be the source of the disease.

The findings provide insight into the spread of potato blight in the United States and public awareness of the disease in the mid-19th century.

Reference: "Using textual analysis to reconstruct historical and modern potato late blight outbreaks," Ariel Saffer, Laura Tateosian, Amanda C. Saville, Yi-Peng Yang, and Jean BRistaino, February 15, 2024, Scientific Reports.

DOI:10.1038/s41598-024-52870-2

Compiled source: ScitechDaily