Nobody really knows how the fungus Bipolaris maydis got into the cornfields of the United States. But by summer of 1970, it was there with a vengeance, inflicting a disease called southern corn leaf blight, which causes stalks to wither and die. The South got hit first, then the disease spread through Tennessee and Kentucky before heading up into Illinois, Missouri, and Iowa — the heart of the Corn Belt.
The destruction was unprecedented. All told, the corn harvest of 1970 was reduced by about 15 percent. Collectively, farmers lost almost 700 million bushels of corn that could have fed livestock and humans, at an economic cost of a billion dollars. More calories were lost than during Ireland’s Great Famine in the 1840s, when disease decimated potato fields.
Really, the problem with southern corn leaf blight started years before the 1970 outbreak, when scientists in the 1930s developed a strain of corn with a genetic quirk that made it a breeze for seed companies to crank out. Farmers liked the strain’s high yields. By the 1970s, that particular variety formed the ... Read more