Cannabis Industry Confronts Billion-Dollar Threat: Weak Weed

A pathogen is contaminating cannabis crops around the country and threatening to leave billions of dollars of losses in its wake. 

Cannabis researchers and experts are sounding the alarm for what is known as hop latent viroid, or HLVd, and cultivators are stepping up efforts to discover whether their plants are infected. The pathogen can drastically reduce the potency of the psychoactive compounds in marijuana, a phenomenon that growers have long called “dudding.”

“It’s a risk within your facility for your healthy plants at all times,” said Miles Sadowsky, chief cultivating officer at Earth’s Healing dispensary in Tucson, Ariz. “It’s kind of like a fox in the henhouse.”

There isn’t a known cure for the viroid, researchers say, and the uneven regulatory landscape for marijuana puts the onus on growers to test and cull infected crops. As a result, it isn’t clear how much dudded marijuana has made its way from grow sites in one state to dispensaries in other states.

Some publicly traded cannabis companies have issued warnings about the viroid to investors. Cannabis sales are estimated to reach nearly $32 billion in the U.S. this year, according to Brightfield Group, a cannabis market-research firm.

Researchers first detected the viroid decades ago in hops, finding an infection could reduce both yield and the compounds in hops that add bitterness and aroma to beer. Unlike viruses, viroids have only been detected in plants and don’t infect humans or animals. 

Pot growers started noticing dudding in their plants more than a decade ago. In 2019, a pair of independent studies linked the problem to HLVd. 

Two years later, a cannabis nursery in California called Dark Heart Nursery detected HLVd infections at about 90% of more than 100 grow sites tested in the state between August 2018 and July 2021. Dark Heart’s 2021 study estimated that the pathogen could lead to $4 billion in crop losses based on U.S. cannabis sales in that year.

The viroid has been identified in cannabis plants all over the country as well as Canada, Europe and Latin America. Plant pathologists and cannabis experts say the spread of the viroid was likely accelerated by the popularity of weed from California, which legalized cannabis for medical use in 1996.

The spread also reflects the evolution of the cannabis business into a major agricultural crop. The risk of a new disease expanding increases for any crop that goes from low to high production, as cannabis has in the past two decades, said Jeremy Warren, Dark Heart’s director of plant science.

“You saw the spread happen in the legal states first, like California, where you started having bigger grows and bigger greenhouses that are making thousands and tens of thousands of plants,” Warren said. “In that system, it’s harder to maintain sanitation and it’s easier for a pathogen to take off.”

The U.S. Agriculture Department typically sets quality standards and inspection requirements for agricultural products, but marijuana’s illegality at the federal level keeps it out of the agency’s purview. Many states and the District of Columbia have legalized pot in some form and created their own distinct oversight groups, so viroid testing standards vary by each cannabis producer.

As long as marijuana remains illegal under federal law, state-level groups lack much-needed engagement with federal agencies that could help them tackle pathogens and contaminants like HLVd, said Gillian Schauer, executive director of the Cannabis Regulators Association, a collection of cannabis-focused state agencies.

Without a step up in government oversight, there are few safeguards in place to stop the spread or ensure infected weed isn’t hitting shelves. “We may have this for another 10 years before we get it under control,” said

Matt Mooney, head grower at Franklin Fields in Lansing, Mich., estimates he lost about $70,000 in 2021 from having to cull a set of plants infected with HLVd. He noticed one marijuana strain, called blueberry muffin, in his flowering room developed weak stems that broke off with a slight touch. He suspected deficient soil or watering.

A friend in the industry, meanwhile, posted on Instagram about dudding being caused by HLVd. A test confirmed that the viroid, which Mooney hadn’t heard of before, had infiltrated his operations. 

The grow operation soon adopted new practices to try to ward off new outbreaks, including going through about 100 new scissors a month and decontaminating them when not in use.

“It was definitely a learning curve to kick-start a lot of new processes that we weren’t doing before,” he said.

Curaleaf, the largest U.S. cannabis company by revenue, has reduced HLVd detection in its crops to minimal levels with extensive testing and so-called clean plant practices that resemble processes used for managing pest and disease. 

“We’re making sure we don’t get complacent,” said Matthew Indest, Curaleaf’s technical director of agronomy and plant improvement. “You can be lulled into a sense of confidence if your testing method isn’t as sensitive as it needs to be.”

Sometimes plants infected by HLVd continue to produce just as well as they ever did. For others, the potency, as measured by levels of tetrahydrocannabinol, or THC, is eviscerated. The pathogen is easily transmitted by contaminated tools or human hands, or through shared root systems or irrigation networks. In all cases, symptoms won’t start showing up until it’s too late.

Once an infection has taken hold, cultivators must isolate and remove the contaminated cannabis to protect the rest of their plants. The flowers are usually then either discarded or, if a grower is hoping to squeeze value out of it, used in extractions for products like vape oils and tinctures.

LFTD Partners, a Jacksonville, Fla.-based maker of cannabis-derived products, in May listed the viroid among its business risk factors, saying the ingredients used in some of its products could become more scarce and costly if HLVd causes significant problems for U.S. hemp growers. Chief Executive Gerry Jacobs said the company’s supplies haven’t been disrupted by the viroid but added the warning in securities filings to make investors aware.

In a business where potency translates to profits, an infection can decimate the market value of a grower’s crops. Some cultivators may require a capital infusion to survive the episode, said Cassin Coleman, vice chair of the National Cannabis Industry Association’s scientific advisory committee. “You can’t pay your electric bill, your lights aren’t on, your plants are dead, and that’s it,” Coleman said. “You’re done.”

Mooney, the grower in Michigan, said the rise of the marijuana business has discouraged cultivators from sharing information about things like emerging risks and best practices. As more states legalized marijuana usage or cultivation, demand shot up but the incentive to coordinate faded, he said. 

“If we’d communicated with one another, we would’ve known this was coming better than learning it off the news or from Reddit pages,” Mooney said.

Write to Dean Seal at [email protected]