How Tackling Hop Latent Viroid Early Can Boost Your Bottom Line

Hop Latent Viroid Dark Heart

These images show the progression of hop latent viroid. Photo: Dark Heart Industries

Dark Heart Industries, a California-based cannabis genetics company, has completed 200,000 tissue tests for Hop Latent Viroid (HpLVd) and uncovered startling new statistics about the impact of the disease on the U.S.’s legal cannabis industry.

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Dark Heart performed tests for more than 100 cannabis growers across California from August 2018 until July 2021. Results show that more than 33% of the tests from almost 90% of the cultivation sites were positive for HpLVd and supports projections by cannabis industry analysts that Hop Latent Viroid affects more than 30% of all cannabis plants. This translates into more than $4 billion in annual losses for U.S. growers who are forecast to produce more than 7 million pounds of legal cannabis in 2021.

“Hop Latent Viroid is perhaps the greatest threat to the legal cannabis industry in the U.S.,” says Dr. Bryce Falk, Professor Emeritus in the University of California, Davis’ Plant Pathology Department. “It is very difficult for growers to identify due to its latency and it can spread undetected within a grow, wiping out much of the commercial value. For cannabis to achieve its potential as a commercial agricultural crop, the industry needs this type of large-scale testing and treatment platform.”

Dr. Jeremy Warren, Ph.D., Director of Plant Science and Laboratory Director at Dark Heart, was the first scientist to identify HpLVd as the cause of dudding in cannabis. Dudding is a colloquial name for a variety of symptoms, which include loss of vigor, stunting, reduction in yield, reduction in potency, and changes in morphology. Under the leadership of Dr. Warren, Dark Heart developed a patent-pending cleaning process to eliminate HpLVd from infected specimens. Over the last four years, Dr. Warren’s discovery and hundreds of thousands of subsequent diagnostic tests have allowed Dark Heart’s lab team to demonstrably eliminate HpLVd.

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“Hop Latent Viroid is impacting legal cannabis crops nationwide, not just here in California,” says Dan Grace, founder and CEO of Dark Heart. “Our new laboratory facility for biotechnology research and innovation in Davis greatly expands capacity to process viroid assays. We now have the scale to support growers and other laboratory facilities from across the country.”

Greenhouse Grower also reached out to Dr. Warren for more information.

Greenhouse Grower (GG): Have you noticed any differences between greenhouse, warehouse, and outdoor growing in terms of the significance of HpLVD?

Dr. Jeremy Warren: If I were to rank the three, indoors is probably the worst for the viroid, greenhouse the second, and outdoors probably third. There’s not a lot of solid research around this, but we can take information we know from other crops and our own analysis. Oftentimes in an outdoor environment, you have that broader range of temperature and more UV light, so the symptoms might not be as severe. But when you step inside that controlled space, you moderate the temperature, so you’re definitely going to be on the higher end of the impact spectrum. Plus, because you can have so many crop turns in a greenhouse, the risk is multiplied. The constant production makes it hard for greenhouse growers to get ahead of it without a concerted effort of testing, making sure you have clean plants, and putting sanitation practices in place.

GG: Can you talk about the cleaning process that you have developed?

Warren: We can’t go too much into detail because it is patent pending, but in doing the research on curing viruses in plants, the first step is always meristem tissue culture. But we’ve found that meristem culture alone does not do a very good job of curing the virus. It’s probably a less than 10% curing rate for meristem, and problems can often pop up six or 12 months down the line, so then you have to do other things like heat or cold therapy. It’s almost like chemotherapy for cancer in people. What we do is torture the plant for a bit so we can detach the viroid from the plant, then we do meristem tissue culture. Beyond that, you really can’t have any sort of control over the pathogen without some sort of diagnostic testing, either with a third-party lab or in house to make sure your crop is clean.

GG: What really stands out is how much of an economic impact this can have on the industry if you don’t manage it. Can you talk a bit more about that?

Warren: Taking care of this problem at the beginning is probably the easiest way to increase your bottom-line income. If you look at the average grow, 90% of the people who send us samples have the viroid, and a typical infection rate is around 30% to 40%. You can get a significant yield increase just from getting the viroid out of your growing facility, and it doesn’t take a long time to do it. What these tests show is if you can get it out within a couple months, you can immediately increase your revenue.

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