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Why Do Some Hemp Crops Produce Too Much THC? This New Study Aims to Find Out

By Leo Bear-McGuinness

Published: Jul 22, 2020   
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On December 12, 2018, the US hemp industry rejoiced. The new Farm Bill had just been passed, formally legalizing any cannabis crop containing less than 0.3 percent THC in all 50 states.

But, nearly two years on, many farmers are finding this THC boundary between legal hemp and federally illegal cannabis is easier to cross than first thought. And instead of harvesting their crops, farmers can be forced to destroy them.

So which factors are tipping these THC concentrations over the legal limit? The soil? The sun? The strain? Right now, it’s not entirely clear. But one research group at West Virginia University wants to change that.  

Hot hemp

“Roughly 10-to-20 percent of the test samples from hemp crops were found to surpass the legal THC limit,” Michael Gutensohn, an assistant professor of horticulture at West Virginia University, tells Analytical Cannabis.

Gutensohn is talking about data from state departments of agriculture in the Mid-Atlantic and Appalachian regions. But the THC failure rate has been much higher in other states.

Earlier this year in Arizona, the Department of Agriculture announced that 41 percent of the 130 hemp lots tested for THC in the state had breached the legal limit. Even by some conservative estimates, these noncompliant acres could have totaled a loss of $13.4 million for the farmers.

“While this does not necessarily mean that these crops had to be destroyed – there is an option to re-test,” Gutensohn clarifies, “it demonstrates that there is an urgency for research and better knowledge about the factors leading to potential THC spikes.”

Funded by a $200,000 grant from the National Institute of Food and Agriculture, Gutensohn and his colleagues have designed a study to help inform farmers why their crops are producing too much THC.

“We will grow a few selected industrial hemp varieties in our facilities here at West Virginia University,” he explains. “We want to test the effect of different individual abiotic and biotic stressors on the accumulation of terpenes and cannabinoids in hemp. Thus, it is absolutely essential to grow the hemp plants under controlled environment conditions.”

“Once we understand how individual factors affect the terpene and cannabinoid metabolism and its genetic regulation in hemp, then we can start to study the effect of combining several factors, which will be closer to the scenario a plant faces when grown under field conditions.”

It’ll take some time – and a lot of overwatered, overheated hemp – to find these factors that really make a difference to THC production. But when Gutensohn and his colleagues do home in on them, there is a preliminary plan to use the facts to develop a genetically divergent, hardier crop system that can keep its THC content low even under extreme conditions.

“It is not our goal to develop new hemp varieties,” Gutensohn clarifies. “However, we hope that the knowledge gained in our research project will help and guide in the development of new improved hemp varieties.”

“The proposed genetic engineering is a common approach in plant science to study how metabolic and genetic networks respond to the inactivation or activation of individual genes in the network. Here we will, for example, inactivate individual cannabinoid/THC biosynthetic gene(s) to study how the terpene and cannabinoid metabolic network in hemp responds to such a modification.”

Other hot hemp efforts

Fortunately for Gutensohn and his team at West Virginia University, the future of US hemp production doesn’t solely rest in their research; other efforts are already underway.

Last December, researchers at Universidad Politècnica de Valencia and the Hemp Trading company in Spain announced the creation of a new hemp strain: Panakeia, “the first THC-free and high CBG content hemp variety.”

In partnership with the US companies Tesoro Genetics and Front Range Biosciences, Hemp Trading plans to distribute Panakeia across the country, and rid the “hot hemp” problem for good.

“The American market is key to the commercialization of Panakeia as hemp is grown here on a large scale, and the agreement with these three companies represents a big opportunity for launching Panakeia in the USA,” Ernesto Llosá, CEO of Hemp Trading, said in a statement at the time. 

Back in January 2019, a partnership between the University of Kentucky and the Kentucky Firm GenCannaGlobal also claimed to have produced a new 0.0 percent THC variety of hemp


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