Reconsidering the lessons learned from the 1970 southern corn Leaf Blight epidemic

Authors: Balint Kurti, Peter; PATAKY, JERALD - University Of Illinois

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2024
Publication Date: 9/14/2024
Citation: Balint Kurti, P.J., Pataky, J. 2024. Reconsidering the lessons learned from the 1970 southern corn Leaf Blight epidemic. Phytopathology. https://doi.org/10.1094/PHYTO-03-24-0105-PER.
DOI: https://doi.org/10.1094/PHYTO-03-24-0105-PER

Interpretive Summary: In 1970, the corn crop was seriously damaged by a disease epidemic caused by southern corn leaf blight, resulting in ~$8 billion in losses in today’s prices. The cause of the epidemic was the fact that most of the corn planted that year carried a specific gene that caused susceptibility to a previously unknown race of the pathogen. This episode has been commonly discussed in the literature as an example of the short sightedness and folly of the corn breeding community that did not realize the dangers of genetic uniformity. Our contention is rather that a degree of genetic uniformity was, and still is, a necessary feature of an efficient modern agricultural system and that, on occasion, this will leave the crop vulnerable to disease in an unpredictable way. The southern corn leaf blight epidemic was a particularly unlucky example of this. In order to mitigate this risk, plant pathologists and plant breeders must work together to monitor, characterize and respond to new diseases. We discuss the fact that the southern corn leaf blight epidemic was solved after a single season and how this is an exemplar of collaboration between pathologists and breeders in public and private institutions.

Technical Abstract: The southern corn leaf blight epidemic of 1970 caused estimated losses of ~16% for the US corn crop, equivalent to ~$8 billion in current terms. The epidemic was caused by the prevalence Texas male sterile cytoplasm (cms-T), used to produce most of the hybrid corn seed planted that year, combined with the emergence of a novel race of the fungus Cochliobolus heterostrophus that was exquisitely virulent on cms-T corn. Remarkably, the epidemic lasted just a single year. This episode has often been portrayed in the literature and textbooks over the last 50 years as a catastrophic mistake perpetrated by corn breeders and seed companies of the time who did not understand or account for the dangers of crop genetic uniformity. In this perspective article, we aim to present an alternative interpretation of these events. First, we contend that, rather than being caused by a grievous error on the part of the corn breeding and seed industry, this epidemic was a particularly unfortunate, unusual and unlucky consequence of a technological advancement intended to improve the efficiency of seed production for America’s farmers. Second, we tell the story of the resolution of the epidemic as an example of timely, meticulous applied research in the public sector for the public good.