If you’re a farmer or a rancher, you probably don’t want ragwort growing on your land. As seen above, it looks like an oversized dandelion but unlike dandelions, ragwort is more than just a weed that’s more than just a minor annoyance. If horses or cows eat ragwort, there’s a good chance it will make them sick, causing cirrhosis of the liver. It’s native to Europe and in those areas, ragwort is less of an issue because cows and horses avoid eating it; its bitter taste is enough of a turnoff to prevent the livestock from grazing where it grows. But in Australia and New Zealand, the cattle and horses aren’t so smart, I guess, because they tend to eat the stuff and get sick.
So, of course, farmers and ranchers try to get rid of ragwort, particularly if they’re in Australia or New Zealand. Both nations have regulations that not only encourage the eradication of the weed but, in some cases, require it.
And about a century ago, these efforts caused an odd epidemic: farmers pants began to explode.
Modern land management, farming, and ranching techniques have ways of controlling ragwort — they’re not perfect, but in general, the efforts are effective (although temporary). Turn back the clock to the 1930s, though, and ragwort control was a lot more trial and error, with “error” winning more often than not. One of the chemicals used back then was sodium chlorate, a compound now primarily used to bleach wood pulp so that our paper is a bright white color. But sodium chlorate is also really good at killing plants. It’s not a great herbicide because it doesn’t discriminate between weeds and crops, but if you really want to nuke some ragwort, it’ll work. We don’t use it that way today very often because sodium chlorate is also toxic to humans — you don’t need to ingest a lot of it in order to be in a heap of trouble.
Oh, yeah, and because of the exploding pants. New Scientist sets up the problem perfectly:
In 1931, the peace and quiet of the New Zealand countryside was shattered by a terrifying new phenomenon: suddenly and apparently at random, men’s trousers began to explode. Some pairs detonated on the washing line, others as they dried in front of the fire. More seriously, some were occupied when they started to smolder. At first, there were just a few isolated reports, but soon the nation was in the grip of an epidemic of exploding trousers.
Sodium chlorate, it turns out, shouldn’t be mixed with organic material. Combine the two add subject it to a heat source and you’ll get a not-so-small explosion; for example, here’s a video of some doofuses trying exactly that with sugar. (Please, please, please do not do this yourself; it’s incredibly dangerous and stupid.) And the organic material doesn’t have to be sugar. Cotton — the stuff most 1930s-era pants are made from — will also go boom if you get sodium chlorate on them and introduce the combo to heat. And the radiant heat from the sun was often enough to trigger the reaction.
According to New Scientist, there were multiple news reports of farmers losing their pants in this unexpected way. One such farmer, Richard Buckley, was “lucky,” per the magazine: “When his trousers blew up he wasn’t wearing them. He was badly shocked, but as the Hawera Star reported on 12 August 1931, his quick thinking saved him from serious injury. ‘While Mr. Richard Buckley’s trousers were drying before the fire recently, they exploded with a loud report. Although partially stunned by the force of the explosion, he had sufficient presence of mind to seize the garments and hurl them from the house, where they smoldered on the lawn with a series of minor detonations.’” That was hardly the only case, and not were as fortunate as Buckley. Atlas Obscura summarizes the details of some other explosions:
One report claimed that a farmer was riding his horse when the friction caused his pants to begin to smolder right there in the saddle. Another pair of pants were hanging out to dry when they suddenly burst into flames. Then there were the unfortunate souls who happened to be wearing their pants when the chemical reaction got started. Some survived with serious burns, while at least a handful of farmers died from the ignitions.
The good news for New Zealand’s farmers is that the Department of Agriculture, even back then, knew that sodium chlorate could cause such an effect (and the farmers figured it out in short order anyway). But the farmers didn’t stop using the chemical, at least not immediately. Farmers donned protective clothing while spraying the chemical, keeping it off their clothes, and they changed out of whatever they were wearing long before the chemical dried and became a fire hazard. But ultimately, they switched away from sodium chlorate — not because it was dangerous to them, but because it wasn’t all that dangerous to the ragwort. Per New Scientist, “once farmers heard that it wasn’t all that good, they started looking for alternatives.” Their pants could finally breathe a sigh of relief.
From the Archives: The President’s Pants: They didn’t explode, but LBJ’s pants are well documented.