Chloropicrin was first synthesized in 1848 by Scottish chemist John Stenhouse but only became an agricultural tool in 1920, when it was used to cure tomato “soil sickness.” After that success it was used to restore pineapple productivity in Hawaii and to address soil fungal problems in California. It became popular as a fungicide, herbicide, insecticide, and nematicide.
In 1940, chloropicrin was first used on potato as a wireworm suppressant and then in 1965 for verticillium. Farmers stopped using it on potatoes after that, because environmentalists claimed chloropicrin “sterilized soil”, that it must contaminate groundwater, and even that depleted the ozone layer, none of which was true. Companies were happy to develop new products to sell in place of an off-patent chemical.
But none of it was true, the compound is destroyed by sunlight, chloropicrin has low solubility and has never been found in groundwater. During that time, farmers have become jaded by persistent scaremongering about agriculture. That’s why it may be making a resurgence. Used as a preplant soil treatment measure, chloropicrin suppresses soilborne pathogenic fungi and some nematodes and insects. With a half-life of hours to days, it is completely digested by soil organisms before the crop is planted, making it safe and efficient.
In more recent studies, chloropicrin-treated soil has a healthier root system, improved water use, and more efficient fertilizer use, along with the ability to suppress many common pathogens, including the pathogen that causes common scab and species of Verticillium, Fusarium, and Phytophthora.
This will add up to more yield, which means less environmental strain and lower costs to consumers.