So You Want To Grow Hemp

21:42 minutes

tractor in a field cutting crops
The hemp research plot at the University of Kentucky College of Agriculture, Food & Environment Spindletop Research Farm was harvested Tuesday monring in Lexington, Ky. Credit: U.K. College of Agriculture /flickr/CC BY-NC-ND 2.0

Good news could be coming soon for anyone interested in hemp, the THC-free, no-high strain of cannabis whose use ranges from fibers to food to pharmaceuticals. If the 2018 Farm Bill passes Congress in its current form, growing hemp would be legal and products derived from hemp would be removed from their current legal gray area.

Universities and private research teams have been busy studying hemp pests, genetics, and other cultivation questions since Congress legalized the research in 2014. Cornell horticulture professor Larry Smart explains why a plant that hasn’t been grown legally in the U.S. for nearly a century will require a monumental effort from scientists to catch up to crops like soybean and tomatoes.

Plus, the majority of U.S. hemp demand is driven by cannabidiol, or CBD, an oil extracted from cannabis flowers. While CBD-containing products have proliferated in recent years as solutions for anxiety, sleep problem, or chronic pain, there’s only one FDA-approved use so far: Epidiolex, a drug for epilepsy in young children.

Dr. Esther Blessing, an assistant professor of psychiatry at NYU Langone Health, breaks down where the research stands on other uses of CBD, and what we still don’t know.

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Segment Guests

Larry Smart

Larry Smart is a professor in the Horticulture Section of the School of Integrative Plant Science at Cornell University in Ithaca, New York.

Esther Blessing

Esther Blessing is an assistant professor of Psychiatry at NYU Langone Health in New York, New York.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. It’s been nearly a century since hemp, the THC-free strain of cannabis, was grown legally en masse in the United States. And we may soon see it again. 

The 2018 farm bill soon to go before Congress looks poised to remove hemp from the list of Schedule I controlled substances and free up farmers to try their hands. Hemp has a lot of potentially profitable uses. After all, you could use the fibers to make clothing and rope. Rope used to be made from it. You can make food, pharmaceuticals. 

But you can’t just wave your hand and turn a new-to-us plant into a thriving crop overnight. Research has been going on in some states since 2014 to understand just what it will take for US farmers to succeed, which strains to grow in which states, which US pests may pose the most risk to a brand-new agricultural market. 

And here to explain that process and what could happen in a more open regulatory environment is Larry Smart, Professor of Horticulture at Cornell University in Ithaca. Welcome to Science Friday, Dr. Smart. 

LARRY SMART: you, Ira. It’s great to be with you. 

IRA FLATOW: Nice to have you. So what exactly don’t we know about farming hemp? Well, we used to farm hemp all the time back before World War II. What don’t we know now about farming hemp? 

LARRY SMART: Well, every crop has its regional specificities. And I will say that there is a lot of hemp grown in Canada and China and Europe. But those cultivars that have been bred for those environments may or may not perform well in the US and, specifically, where I am in New York state. So one of the first things that we’ve been doing is evaluating commercially available cultivars so that we can give good advice to farmers on what they should grow. 

IRA FLATOW: And then you have to rediscover what pests are going to attack the crop? 

LARRY SMART: That’s right, pests and diseases. And in fact, at Cornell, we’ve identified a new species of fungus that was also identified in Kentucky, which is a pathogen of hemp that had never been described before in the genus Bipolaris. 

IRA FLATOW: And we don’t– do we have a genus? Of do Have we looked at the genome of hemp yet? 

LARRY SMART: Yeah. In fact, there have been a few genome sequences that have been released, some in the last month. So yeah, there’s a lot of interest in using genomics to speed our breeding program and to better understand the biochemistry of industrial hemp. 

IRA FLATOW: What would you describe hemp most like? What kind of other crop would it grow like? 

LARRY SMART: Well, hemp has been bred for multiple market classes. So when you think about the grain, it’s a lot like wheat. When you think about the fiber, it’s a lot like flax. But it also has these medicinal properties. So it really has been tailored for multiple uses. But we hope that the future expansion will be in the grain and fiber markets. 

IRA FLATOW: There’s one piece of language in the bill, as it was last written, that seems a bit counterproductive, and I’m talking about the part that says, you couldn’t be involved in growing hemp if you have a drug-related felony in your history. Wouldn’t that rule out a lot of people with valuable expertise related to, say, growing marijuana? 

LARRY SMART: Well, over the last several decades, a lot of the work on cannabis sativa, which is the binomial for marijuana and hemp, has been done underground, so to speak, or in basements. And there is a certain amount of expertise. But I will say, as a university scientist, it’s been a challenge to sort out the scientific veracity of the work that’s available on the internet. 

IRA FLATOW: And of course, if this bill comes forward, you would deschedule it from Schedule I, which has been very preventative from science for actually researching the plant. 

LARRY SMART: Exactly. And again, as a university professor, I don’t want to put Cornell University in legal jeopardy. And yet, this is a crop that’s regulated by the Drug Enforcement Agency. So at times, we’re a little bit nervous about that. 

IRA FLATOW: I’ll bet. But people are already growing hemp in different states, aren’t they? 

LARRY SMART: Yes. Kentucky, Colorado, and Oregon have been the leaders. New York and North Carolina are right behind them. And we’ve received very enthusiastic support from Governor Cuomo and New York State Ag and Markets. 

IRA FLATOW: Let me give out our number– 844-724-8255. We’re talking about hemp here. And we’re going to get in a little bit in a few minutes into the medicinal aspects of it. 

Now, hemp has been illegal to grow for nearly a century. Well, what has that cost us in terms of agricultural progress? 

LARRY SMART: Yeah. One of the costs has been in plant breeding. And in fact, plant breeders rely on a broad germplasm repository material that’s collected around the world and, in particular, from the site of origin of the species, which has the greatest genetic diversity. 

We, in the US, rely on the USDA to maintain those germplasm collections. And when the Controlled Substance Act passed in the ’70s, our germplasm collection was destroyed by my understanding. 

IRA FLATOW: Does that mean that if we’re going to grow hemp in any large quantity, we have to go abroad and bring the seeds in because we don’t have our own? 

LARRY SMART: That’s what we’re doing right now, yes, is we’re importing cultivars that have bred in Europe, in Canada, and in China. But it’s my hope, personally and at Cornell University, to establish a long-term academic public breeding program so that we can have domestically produced and selected cultivars of industrial hemp. 

IRA FLATOW: Give me an idea of what kinds of cool stuff you can make with hemp. 

LARRY SMART: Well, you mentioned that in colonial days we produced hemp as a fiber source for rope and fabric for the British Navy. But these days, we’re taking those fibers and making industrial composites that can replace fossil fuel based products. So it can be a bio-based replacement for fossil fuels. 

But on the food market, there are a lot of opportunities. It’s a very healthy oil and protein source. And people are being very creative. So one of my favorite food products is to replace hops with hemp– they are close relatives– to make a craft beer– so the flavor of hemp instead of the flavor of hops in your beer. You should try it. 

IRA FLATOW: I’m waiting. I don’t think there’s any better way to get people to adopt hemp than to put it into beer. We love craft beer around here. Do you have to harvest a big field? I mean, do you have to grow it in greater quantities in order to harvest it? Can you get as much production out of the same kind of farming? 

LARRY SMART: Yeah. So the harvesting operations will be a challenge for farmers to pick up. Again, thee are different harvesting operations for grain, for fiber, or for CBD, the medicinal compound for CBD. It’s largely a horticultural production system similar to tobacco or tomatoes, very labor intensive right now. 

For grain, it’s a little bit simpler, similar to combining wheat. And that would be done most efficiently on large acreage. And then for fiber, there is a lot of processing involved to convert that plant material into a usable fiber source. 

IRA FLATOW: How different is the plant you would grow for hemp for material and fiber different than you would grow for CBD? 

LARRY SMART: Right. So the fiber, we want tall, thin stems. So it grows to 12 to 14 feet tall, while the plants grown for CBD are shaped more like a Christmas tree. They’re very branchy because we’re trying to get the flower buds on the tip of every branch. 

IRA FLATOW: So it’s not the stuff that people were growing in the ’60s. 

LARRY SMART: So again, cannabis sativa has been selected for high THC production– that’s marijuana– or for high CBD and low THC production, and we call that industrial hemp. 

IRA FLATOW: So you’re excited about this, I would imagine. 

LARRY SMART: Oh, it’s exciting. I learn something new every day. And the other thing, it’s generated incredible excitement in the public and especially among young people. We have an aging farmer population, and this has really spurred interest in young people, in plant science and in agriculture, again. 

IRA FLATOW: Let me see if I can get a quick call in. Amy in Manhattan, hi, Amy. 

AMY: Hi. I’m wondering if there are any environmental implications. If anything’s problematic, how might that be addressed? 

IRA FLATOW: OK. Good question. 

LARRY SMART: Well, as with any crop, when we add it to the landscape, it potentially will have some impact on other crop species and on other species in general. One thing we’ve learned early on is that the pollen of hemp is very attractive to bees. And it may actually fill a niche in the middle of the growing season, providing a food source, especially for bumblebees. So that’s a potentially positive impact on our pollinator populations. 

IRA FLATOW: Wow– all these things that you hadn’t thought about. 


IRA FLATOW: I mean, there could be other things, other good things that come out of this we haven’t thought about. 

LARRY SMART: Well, and one possible negative thing, again, we need to think about diseases and disease epidemics. And we found that industrial hemp is very susceptible to a disease called white mold, which also affects soybean and other beans. So putting hemp in a rotation with other bean crops may increase the incidence of white mold disease. 

IRA FLATOW: All right. It’s good to– the yin and the yang in the whole thing. 

LARRY SMART: Exactly. 

IRA FLATOW: Larry Smart– Professor of Horticulture at the famous Cornell University in Ithaca where they have a great Agricultural Department. Thank you for taking time to be with us today, Larry. 

LARRY SMART: It was great to be with you, Ira. 

IRA FLATOW: I want to switch gears slightly now. As my last guest had mentioned, a big reason farmers are interested in hemp is CBD, cannabidiol. Just this June, the FDA approved the first drug made from CBD called Epidiolex, and it’s approved for treating two rare forms of epilepsy that young children can have. 

But in the meantime, it seems like you can find CBD-infused products nearly everywhere, and people take it for everything from pain to PTSD to sleeping and all without the FDA’s involvement. So what do we know so far? What don’t we know yet about the benefits and safety considerations of CBD? 

My next guest is one of the many researchers asking those questions, Dr. Esther Blessing, a researcher and Assistant Professor of Psychiatry at NYU Langone Health here in New York City. Welcome to Science Friday. 

ESTHER BLESSING: Hi, Ira. Pleasure to be here. 

IRA FLATOW: CBD is all the talk right now. It seems to be everywhere. Right? 

ESTHER BLESSING: Absolutely. Yeah. 

IRA FLATOW: I’m hearing podcasts advertise it. You can buy CBD-containing products in grocery stores. Why suddenly this explosion? 

ESTHER BLESSING: I think it’s come from a lot of really exciting discoveries in basic science and clinical trials as well as this sudden push in the advertising industry for CBD-infused products. And there are two very different types of evidence or one without evidence. Yeah. 

IRA FLATOW: Yeah. And you are researching CBD specifically for anxiety, PTSD, other psychiatric issues. What’s happening so far? Where have we gone? 

ESTHER BLESSING: I think it’s really important to know that there are no clinical trials that have yet been completed in any anxiety disorder, including PTSD. And those types of clinical trials take years to complete, and they’re probably at least one or two years away. 

But even so, there’s promising preclinical evidence, which comes from rodent models and also from human experimental studies. And these studies have shown that CBD, when given to, say, normal volunteers, can reduce the anxiety that you experience when giving a public speech. And they were placebo controlled– a number of small studies. And the doses that were effective in those studies was something between 300 to 600 milligrams. And also, social anxiety disorder subjects were studied, but they’re very small studies. 

And that type of evidence isn’t the sort of thing that can really tell us about a clinical dose in an actual patient who’s been diagnosed with anxiety or PTSD. Also, studies in rodent models have shown that CBD inhibits activity in areas of the brain that cause anxiety. So that’s the type of evidence we have. But in order to be able to say, here’s the dose that’s going to treat anxiety or PTSD, that evidence is a long way away. 

IRA FLATOW: I’m Ira Flatow. This is Science Friday from WNYC Studios talking about CBD with Dr. Esther Blessing. Of course, with any drug, don’t you have to, even if you know what dosage range, don’t you have to continually adjust it up and down for each individual patient to see what the the best dosage is for that person? 

ESTHER BLESSING: Absolutely. And CBD, in particular, might be very variable between individuals because of the way it’s metabolized. But even to get that initial range, those types of clinical trials need to be conducted. 

And there may be some complexities in how CBD is dosed for anxiety. So there’s some evidence out there that maybe higher doses are less effective and lower doses are not as effective. So there probably is a range that’s effective. And if people are kind of just playing around with things they buy, which often have much lower doses than 100– they’re more like 10 or 20– it’s unlikely that they’re going to be getting a therapeutic range. 

IRA FLATOW: And not only that, people may not know what they’re getting. 


IRA FLATOW: Right? If it’s not regulated, which it isn’t now– 

ESTHER BLESSING: Absolutely. The standards for a nutritive product or a food product are completely different from the standards for a pharma-grade product. And so it’s quite possible that these things you buy in the street or in a latte or something have traces of THC or other cannabinoids in them or whoever knows what. 

And the amount of THC that’s required to cause an effect is much, much less than CBD. So you could have even less than 10– around 10 milligrams of CBD would cause an effect, like impair your driving or concentration. And so if there’s even a trace amount of THC in these substances and you take a lot of them, you’ll get a significant amount of THC. Yeah. 

IRA FLATOW: Let’s talk about this one CBD drug, Epidiolex. What is that being prescribed for? How does that work? 

ESTHER BLESSING: Right. So research at NYU Langone by Professor Orrin Devinsky, he’s conducted several large randomized controlled clinical trials in childhood epilepsy, as you mentioned, rare forms of childhood epilepsy that are resistant to treatment with other agents. And that’s shown that whenever dialects is added as a treatment to their standard treatments, there was a significant reduction in seizure frequency and overall clinical wellness, which is really exciting. 

IRA FLATOW: It’s interesting that there are receptors in the brain for CBD. I mean, like, how did the brain know it wanted to use this– you know what I’m saying– this drug? 


IRA FLATOW: We evolved in receptors for them. 

ESTHER BLESSING: Yeah. It’s interesting. It’s really interesting that there should be these two chemicals in cannabis that have such different effects. 

But so most of the knowledge on how CBD affects the brain comes from rodent studies and only a select few human neuroimaging studies. We really don’t know. This is just getting started. But CBD seems to affect a lot of different receptors in the brain. And overall, it seems to reduce activity in areas of the brain that cause anxiety, like the amygdala, reduce hyperexcitability there, and improve activity in areas of the brain that regulate anxiety, like the prefrontal cortex. 

And it probably does this by increasing levels of a neurotransmitter called Anandamide, which comes from the word for bliss in Sanskrit. And this neurotransmitter, which is released in response to stress or activity, dampens down the stress response. 

IRA FLATOW: Gotcha. 


IRA FLATOW: And we’ll talk more about it with Dr. Esther Blessing. Our number– 844-724-8255, talking about CBD as a medication. We’ll be right back after this break with more talk about it. Stay with us. 

IRA FLATOW: This is Science Friday. I’m Ira Flatow. We’re talking with Dr. Esther Blessing, a researcher and assistant professor of psychiatry at NYU Langone Health about CBD and possibilities for its use. 

Seems like all kinds– let me go to the calls because we have some interesting calls on here that– Alfonso in Tracy, California, hi, welcome to Science Friday. 

ALFONSO: Good afternoon, guys. Thank you. I wanted to say thank you for having this program. Science Friday is been informative. Yes, my name is Alfonso. I’m from Tracy, California. Ira and Dr. Esther Blessing, I have a question regarding the hemp, using CBD in addiction issues. I won’t get into too much detail exactly what the addiction is. But what kind of help, doctor, in CBD, the oil of hemp, maybe in [INAUDIBLE] that is known? Could that be helpful at all? 

ESTHER BLESSING: Well, again, there’s no clinical trials that have been conducted in addiction yet for substance use. But there is evidence from work from Professor Yasmin Hurd at Mount Sinai that CBD could reduce craving in abstinent heroin users. And in general, CBD affects the brain in a way that should reduce activity in addictive circuits and increase activity in regulatory circuits. So there’s good suggestion that could be useful, but clinical trials are needed. 

IRA FLATOW: And we haven’t had a chance to do any of those trials until now. 

ESTHER BLESSING: Yeah. And the sort of decrease in regulations would be exactly what’s needed. 

IRA FLATOW: What other kinds of mental illnesses or problems might CBD help? 

ESTHER BLESSING: So there’s been two clinical trials, controlled clinical trials in treating schizophrenia, and CBD was as effective as an antipsychotic drug in treating schizophrenia. And that was a small study, so it’s only preliminary evidence. 

And then when added on to regular treatments, it improved symptoms over those treatments. So there are to two clinical trials that suggest potential for treating schizophrenia, as well, which is really exciting. 

IRA FLATOW: So are you saying that we should have a large scale testing of CBD and in lots of different fronts once it becomes descheduled? 

ESTHER BLESSING: Absolutely. I think– 

IRA FLATOW: What would be the best case for you? What would you think? 

ESTHER BLESSING: Well, I just think that CBD is really exceptional. There’s been no other drug in the history of neeuropsychiatry that has the potential to treat so many different disorders. I’m not saying that it does treat them all, but the evidence is good so far. 

So it would be ideal to put aside all of these issues of legality and the fact that it comes from the cannabis plant and start to be able to treat it as a medicinal agent with controlled clinical trials and get it out to people who need it as quickly as possible. 

IRA FLATOW: That’s interesting. Calvin on Twitter says, with the legalization of cannabis and opening of markets growing rapidly, what new directions of research you’ll see opening with industry funding. Should industry be doing a lot of this research or is the government, NIH, people like that be doing it? 

ESTHER BLESSING: I think these types of large clinical trials really need a partnership between all these groups, industry, NIH, and clinicians because, obviously, companies need to be able to be incentivized to provide a drug that can give a long-term supply. But this sort of funding that you need for large clinical trials really needs a private-public cooperation. 

IRA FLATOW: Last question to you– while we await the scientific verdict in the legalization, national legalization on taking it off Schedule I, what should consumers do? I mean, it’s all around them now. 

ESTHER BLESSING: Right. I think that people need to be aware of a safety issue, first of all, which is that CBD can interact with other medications. So don’t go out there and take a lot of these small dose stuff things that you can get on the street because they might interact with medications you’re currently taking. And then we just need people to step up to increase funding for research. That’s the answer. Yeah. 

IRA FLATOW: That’s a good place to stop. Thank you very much, Dr. Blessing. 


IRA FLATOW: Dr. Esther Blessing is an Assistant Professor of Psychiatry at NYU Langone Health here in New York City.

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