Researchers Are Collecting Feral Hemp to Study Its Potential Impact on the Industry

Departments - Smart Start Research Roundup

A Western Illinois University professor’s research picks up where the war effort left off and revisits the potential impact of hemp growing in the wild.

March 27, 2020

With a permit from the U.S. Department of Agriculture, Win Phippen spent the summer searching the northern part of Illinois for feral hemp to characterize and trace its thread to the now-flourishing industry.
Photos courtesy of Win Phippen

Though the Marihuana Tax Act of 1937 effectively banned hemp cultivation, the federal government briefly lifted the ban and encouraged cultivation during World War II through its promotional “Hemp For Victory” video. That effort planted the seeds for a hardy, industrial form of hemp that has now thrived in the wild for decades.

Commonly known as ditch weed, feral hemp has been recognized by the Drug Enforcement Administration (DEA) as “wild, scattered marijuana plants [with] no evidence of planting, fertilizing or tending.” This hemp is especially prominent in the Midwest and has long been known to have a negligible tetrahydrocannabinol (THC) level.

But to Win Phippen, Ph.D., a professor in the School of Agriculture at Western Illinois University, ditch weed could have broad implications for today’s booming hemp industry. Are those THC levels, for example, low enough to meet the federal 0.3% limit? Even if they contain no THC at all, could pollen from the fibrous feral male plants contaminate fields of the cannabidiol (CBD)-rich hemp grown for flower? Or, on the flip side, could the feral hemp be worthy of breeding to produce varieties that thrive in the state?

Phippen had questions, and he set out to address them in the summer of 2019 by searching for feral hemp throughout the state to characterize and trace its thread to the now-flourishing hemp industry.

Phippen has been the director of the university’s alternative crops research program for two decades, but he didn’t start working with hemp until early 2018. It only took a year of working with farmers for him to see that researching feral hemp could help farmers address one of their biggest challenges.

“The challenge a lot of our Illinois producers had was [finding] seeds. … I’m a plant breeder by training, and so my thought was, well, why don’t we collect the wild stuff?” Phippen says. “It’s been in the wild since the war, so it’s well-adapted to Illinois growing conditions. It’s actually a good place to start for someone who’s interested in being a hemp breeder in the state.”

Though hemp is now federally legal, feral hemp in particular has a controversial past. The DEA spent at least $175 million eradicating 4.7 billion wild hemp plants from 1984 to the mid-2000s, according to Vote Hemp. Its efforts were particularly strong in Illinois, where the agency led efforts to eradicate about 11 million wild hemp plants per year, ranking the state third in the country behind South Dakota (nearly 69 million) and Indiana (more than 66 million) for the most plants destroyed.

Phippen holds a cutting of wild hemp he rooted and hopes to use to produce seeds.

Despite industrial hemp’s legalization, Phippen still needed a permit from the U.S. Department of Agriculture to collect feral hemp. After receiving the permit, he began putting calls out to Western Illinois University alumni in July 2019 to see if they had any feral hemp on their properties. Some of his efforts involved serendipitous searching. He drove around until he spotted areas heavy with greenery and plodded through open fields, roamed down stretches of highway and even wandered into a backyard or two to find the camouflaged cannabis.

“You could find it anywhere,” Phippen says. “There’s some counties where you can get out of the car and just start walking along some power poles along the highway or something like that, and there it is. You could go around any corner and find it.”

In counties where he had trouble finding feral hemp samples, Phippen resorted to asking for help from the local sheriff’s office, who he said would discreetly point him to a general location they knew about.

By the end of the summer, Phippen had collected 27 different samples from 13 of Illinois’ 102 counties, mostly on the northwestern side of the state. The good news: None of the feral hemp tested “hot,” or above the legal 0.3% THC limit. 

“We did see some phenotypic differences between the wild stuff, but for the most part, they are remnants of the old fiber industry,” Phippen says. “Four of my collection sites were from original farms that grew during the war effort, and they are clearly remnants from the war effort.”

Phippen, however, has concluded that those growing for CBD may be best served doing so indoors. He says that when he was helping farmers grow hemp for CBD in 2018, they experienced some cross-pollination even on farms “out in the middle of absolutely nowhere.” Phippen suspects the feral hemp may have played a role. (For more on pollen drift, read “Hemp Law: Drifting Into New Legal Territory” at:

“We were probably 4 miles away from the nearest forest area that could have wild hemp, and we still had seed production in our CBD plants, so that would indicate it was either in the wind or insects were visiting,” Phippen says. “A lot of producers had a bad experience with CBD this year, so a lot of them are going to start switching over to seed/grain production and fiber production. Those two types of producers are going to produce a tremendous amount of pollen. That’s why if you’re going to be really vested into CBD production, you probably want to go indoors, because there’s not much you can do about stopping the pollen from coming in.”

Phippen presented his findings at the Illinois Hemp Summit in December and plans for them to be featured at the university’s undergraduate research day in April as well.

Looking ahead, Phippen’s hemp focus will revolve around helping the university get its recently announced cannabis minors off the ground, as well as develop a related major to launch in the future.

But Phippen’s feral hemp research may follow him longer than he initially intended. He still fields phone calls from people who find feral hemp and want him to check it out, and he predicts he’ll end up going on another hemp expedition this summer. His ultimate goal is to offer seeds from the wild varieties he collected to those interested in starting a breeding program for hemp grain and fiber production, picking up on an effort that has remained stagnant since WWII.

Theresa Bennett is associate editor of Hemp Grower and sister magazine Cannabis Business Times.