Blackcurrants were outlawed in America in the early 1900s because they spread a fungus that killed white pine trees. Shutterstock/twinlynx

The blackcurrant, a small, tart berry, that when married with sugar can be made into jams, sauces, syrups, fruit drinks, and purple candy, is popular across Europe. But most Americans struggle to describe its flavor.

"A large majority [of Americans] have never eaten one — probably less than 0.1%," Marvin Pritts, a professor of horticulture at Cornell University, told Business Insider.

This was not always the case.

In the late 1800s, US farmers grew around 7,400 acres of blackcurrants, gooseberries, and white currants, together known as Ribes species, with New York state leading production, according to a report in the journal HortTechnology.

Then, disaster struck.

Pathologists discovered that blackcurrants spread a fungus, introduced from Europe in the 19th century, that killed white pine trees, the backbone of the nation's timber industry. The federal government took aggressive action: it outlawed the commercial growth of blackcurrants in the early 1900s and financed a program to eradicate Ribes plants.

Crews outfitted with backpacks of chemical spray fanned out across the country. As field after field of Ribes were destroyed, the American consumer's memory of the deep purple fruit was also erased.

America's war against blackcurrants

The bark of a pine tree is covered with yellow cankers caused by the blister rust infection. Wikipedia

By the 1800s, America was cutting down white pine forests for timber at such a rapid rate that the nation's nurseries could not keep up. So farmers began turning abroad for cheap tree planting stock. The result was the importation of seeds infected with a parasitic fungus called blister rust. Blister rust first alarmed US officials in 1909 when it was found on a New York plantation of white pine trees grown from seedlings brought over from Germany, according to the book "History of white pine blister rust control: a personal account" by Warren V. Benedict, the former director of the United States Division of Forest Pest Control.

The problem with blackcurrants is that blister fungus — characterized by "yellowish, elongated swellings" — does not hop directly from pine to pine. For the disease to complete its life cycle, it must infect a Ribes species before returning to the needles of white pines and spreading into the bark. Authorities believed the only way to save America's pine trees was to get rid of these intermediary hosts, which had far less economic importance.

"So discovery of a few small pine trees infected with blister rust was to trigger a gigantic fight that has been waged coast to coast for 70 years," Benedict writes.

Blackcurrant cultivation in the US was restricted in 1911, followed one year later by a ban on the importation of white pine seedlings from Europe.

Blackcurrants take a different path in Europe

Ribena is a popular blackcurrant drink in the UK. Rui Vieira/PA Archive/Press Association Images

Blister rust fungus was a well-known nuisance in Europe before it was brought to America. But in contrast to the US, Europe had few commercial pine tree plantations. Blackcurrants, on the other hand, had been an important crop for a long time. "In Europe the white pine was sacrificed to retain the Ribes," writes Benedict.

Currant production share by region. FAOSTAT Today, Europe produces 99.1% of the world's currants (which lumps blackcurrants, red and white currants, and sometimes gooseberries into one group), according to the Food and Agricultural Organisation of the United Nations. Two-thirds of blackcurrants produced in Europe are used for juice, according to a 2007 report from the European Commission.

In England, a blackcurrant cordial mixed with water gained popularity as a vitamin C supplement given to children to prevent scurvy during World War II, after Germany's U-boat campaign prevented citrus fruits like oranges and lemons from entering the UK. Brits will know the name — it's called Ribena.

In 2010, 90% of all blackcurrants grown in Britain were destined for Ribena's bottling factory in Gloucestershire, according to The Guardian. Ribena and energy drink Lucozade did roughly £500 million in combined sales for GlaxoSmithKline in 2012, according to the Financial Times. Both products were sold to a Japanese company in 2013 for over £1.3 billion.

Blackcurrants find a champion in the US

Greg Quinn on his farm in Hudson Valley, New York. Greg Quinn

In 2003, Greg Quinn, a children's book author with a background in horticulture, successfully lobbied to have the blackcurrant ban overturned in New York state. By this time, the regulation of blackcurrants had been entrusted to each state. It is now believed that the plants can thrive under proper management, according to Pritts, especially after the development of disease-resistant blackcurrant varieties.

Blackcurrant production is not tracked by the US Department of Agriculture so it is hard to know how many are grown and where, though Pritts suggests there is a "thriving group" of blackcurrant farms in the Hudson Valley of New York and Connecticut, as well as Oregon, Washington, British Columbia, and Canada.

And, of course, there is Quinn, who grows about 16,000 pounds of blackcurrants on his farm in the Hudson Valley region of New York. He sells 15 different blackcurrant-based products under the brand CurrantC. The company's flagship product is blackcurrant nectar, which costs $9.99 for two 16-ounce bottles on his website.

In America, purple candy is generally synonymous with the flavor grape. Shutterstock/Dan Kosmayer It is easy for Quinn to gush about the potential of blackcurrants and how he uses them to cook up glazes for game and pork. But outside of his own kitchen, Quinn said he is still "pushing the rock up the hill to introduce to people blackcurrants."

"This may be the last product that everybody knows about except the US,” Quinn said.

It also explains why purple Skittles (and other purple hard candies) are synonymous with grape flavor in the US, but taste like blackcurrant in other countries, including the UK and Australia, as pointed out by Atlas Obscura.

There are some challenges to growing blackcurrants — they tend to be susceptible to leaf diseases, for example — but the biggest hurdle is marketing and selling them.

"Consumers just don't know what to do with them," said Pitts, "particularly since their taste is off-putting to most Americans."