This is the sixth and final in the series of articles designed to introduce an integrated pest management framework for cannabis cultivation facilities. To see Part One, an overview of the plan and pest identification, click here. For Part Two, on pest monitoring and record keeping, click here. For Part Three, on preventative measures, click here. For Part Four, control methods, click here. For Part Five, pest control action thresholds, click here.
This is Part 6: Emergency Response
When all prevention efforts have failed and your escalation procedures must be implemented, your emergency response document takes the stage.
Figure 1: We never want to see these at our door
It sounds obvious, but your emergency response document is your team’s guide to structure your response to an emergency. This begins with the simple definition of what is an emergency for your business. Emergencies can be to your personnel (personal injury) or your infrastructure (broken pipes/floods, power failure), and finally, a pest or pathogen outbreak that threatens the entire facility (insects/fungus, molds). Be sure to get the advice of your local service providers on the important things to put in to your response plan. This article is far from an exhaustive list, but it can get you started quickly with the basics for example purposes.
Personal Injury
Personal injuries are the events where you would call your local fire or police resources after stabilizing trauma events. Examples are chemical exposure, cuts, lacerations or broken bones from falls or crush events, burns, electric shock or earthquake or weather events. Injury response is to assess, call for medical assistance if appropriate, provide first aid and stabilize the injured, move to safety if possible, treat the injury and after the event is over and still fresh in everyone’s mind, consider what can be done to avoid the repeat of this or similar events in the future. Work those changes into your standard operating procedures.
Emergency Response to Facility Events
Figure 2: Cultivation IPM Prevention with Beneficial Insects
Whether the event is broken pipes or flooding, power failure or interruption, fire, HVAC failure or weather event, emergencies come in all sizes possible. It is likely that you built up a plan for emergency response as part of your city permitting process. Be sure to use those experts to refine your plan to include your operations.
Broken pipes start with the basics of turning off the source feeds and fixing the plumbing. If the water is actually rich fertilizer nutrients, cleaning and disinfectant is necessary as part of the drying and mop up process.
Environmental damage from fire, HVAC or weather event, lead to immediate treatment to try and save the current crops. This would include manual watering/misting, portable heater/cooler/CO2 burners. Verifying that backup power supplies turned on as planned. Are emergency fixes sufficient to power or run the systems necessary for plant life until power is returned?
Cultivation Events
Figure 3: Emergency Response Team Investigating Treatments
This entire paper has been about pest management, so emergency is expected to mean a pest or pathogen outbreak. We defined the escalated response actions up to the point of direct action and chemical interventions in chapters four and five. Your emergency response plan takes those actions to a site wide effort. Identify the pest and location/s that are causing the crisis, isolate the infested plants, remove the infected materials, clean, disinfect, and purify the contacted surfaces. Follow your plan and contact your emergency leaders.
Emergency Response Team
Your emergency response document identifies each of your team leaders and executives that are to be contacted in the event of an emergency. These leaders should be identified in the document with contact details and methods/on-call schedules for days and times of responsibility (after normal hours and holidays included). Someone is always on-call. The personal injury, facility and cultivation lead responsible should be identified and aware that they are the assigned resource and to treat emergencies as a priority.
Figure 4: IPM Preparation – Put It All Together for Success!
In Conclusion
We have covered an example integrated pest management philosophy from prevention through observation to limiting expansion to treatment and review. This continuous monitoring and learning process is a living document of standard operating procedures for any facility.
The attention of your team, their scouting observations, and attention to detail give you an opportunity to address and restrict any pest outbreak before it destroys your crop. Teach your operators well and reward them for their attention to your plan.
Clean and sterilize your facilities regularly. Preventing the emergence of pests will pay for the investment in a multitude of ways in both savings and profits. Plan your response thresholds and use traps to monitor your escalating protections. Target your treatments and remediations to match the threats to your harvests. As a last resort, apply approved chemical treatments judiciously to minimize the impact on non-target organisms.
Evaluate the effectiveness of your plan on an annual basis. Put your improvements to work for you to minimize your pest footprint and to increase your profits in every harvest.
This is the fifth in a series of articles designed to introduce an integrated pest management framework for cannabis cultivation facilities. To see Part One, an overview of the plan and pest identification, click here. For Part Two, on pest monitoring and record keeping, click here. For Part Three, on preventative measures, click here. For Part Four, control methods, click here. Our final chapter, Part Six, discussing emergency response, comes out next week to wrap it all up.
This is Part 5: Pest Control – Taking Action
Previous chapters have covered the many preparations you can take to protect your facilities from pest attacks and outbreaks before they get started. This chapter will summarize the concepts of pest control thresholds and the actions you can take for the painful event when you surpass those limits (and various examples). The Integrated Pest Management (IPM) recommendations provide you with a framework for these plans.
Figure 1: Cleaning regimen, the heart of successful operations – no biofilm buildups
Preventative actions are part of your regular site operations; in other words, they are how you avoid problems before they happen. Just to hit this action one more time: cleaning must be fundamental to your facility. Water sanitation and changing filters must be done on schedule and frequently to avoid biofilm build up and nasty self-multiplying eco-systems.
For each of the rooms in your facility, identify the acceptable tolerance level for each type of pest that you may encounter. Define the intervention levels per room: preventative, direct action and escalated direct action. Follow your predefined procedures and defend your facility. Let’s cover high, medium and low tolerance example responses.
High Threshold for Tolerance
For example, the impact on your plants, your profits and your yields from the discovery of a white fly fluttering inside of one of your flower rooms may be very small. If this presence is late in your harvest cycle, your tolerance of this discovery may be very high. Your team could take preventative actions to clean the room more aggressively or to check your traps more frequently, but you are probably not going to want to invest in aggressive actions at that time in the harvest cycle.
Move from passive observation to the shake test. With sticky traps in place, shake or brush your plants. Do you see the bug counts increase on your test sheets?
As that infestation grows, you may set a threshold for direct action (i.e. 5-10 flies per trap per week). If you reach that level, implement a treatment action with a non-chemical microbial biofungicide to stop growth in the roots or neem oil as a direct chemical action.
When you reach your escalated threshold of 10-20 flies per trap or direct plant damage is apparent, an infestation is more serious. In that event, you may choose to take steps to directly reduce the pest population with knock down sprays of approved direct chemical pesticides like citric acid or insecticidal soaps. Be sure to use your Personal Protective Equipment (PPE) for breathing and contact safety if you get into this situation.
Medium Threshold for Tolerance
Depending on the timing in your harvest cycle, the discovery of fungus gnats in your grow room may trigger a medium level alarm for you. Is the location, a small example with a minimal frequency? Is this addressable with additional attention to cleaning the area and longer dry periods in the irrigation or is this the beginnings of an infestation? Fungus gnats feed off of fungus or organic matter in soil triggered from an overly moist root environment. You may choose to react with immediate cleaning at the first existence in a room. Or you could set your “Medium” level alert status to be additional sticky trap distribution at the first visible gnat. If those counts reach 10-20 gnats per sticky trap per week, begin your foliar spray regimen with Zerotol or the equivalent.
Figure 3: Fungus Gnats
If these counts do not respond to your treatment, meaning that the next sticky trap count reaches beyond 20+ gnats per trap or visible direct plant damage, then institute your root drench protocol with a solution of BActive 1-2 times per week until the problem is under control and the counts are reduced. If the growth continues, look to approved pesticides in your area (as an example, AzaGuard Asadirectin).
Low Threshold for Tolerance
Alternatively, you may have a unified air circulation system due to facility limitations. Your air circulation may be shared across all of your mother plants, clones, veg and flowering plant areas. In that case, any presence of an airborne fungal infection like powdery mildew would have a very low tolerance of acceptance. Selective de-leafing of the infection and increased airflow are your first defense. Any visible presence beyond that would trigger a low threshold alert and immediately start a preventative action, such as carefully removing the infected plant material much wider than a few leaves and treating the area with foliar sprays like Zerotol (hydrogen peroxide plus).
If the penetration continues or expands, treatment would escalate to minimal risk pesticide follow up and observation. Chemical oils or citric acid might be in your mix in this case.
Figure 4: Powdery mildew in cannabis – Ryan Douglas Cultivation LLC
Finally, if repetitive treatments once a week are not turning the tide, increasing to once per day or even once per ON/OFF lighting cycle until the infection is controlled. At this point, you may decide to strip the room down and start over. Clearly the choice to “throw in the towel” is a total loss of the crop, but it may be the best option relative to minimal yields and failed flowers that will not sell.
Pest Control Actions
Our Integrated Pest Management recommendations paper gives you examples of what to consider for plans with white flies, fungus gnats, root aphids, powdery mildew and biofilm on plumbing or surfaces. These follow the preventative action, direct action, escalated direct action and pesticide approaches for each example. These are options to plan for water sources, root treatment, tunneling, crawling and flying phases.
In summary this week
As covered, preventative measures are your best defense. Hire expert consultants and plan these well. Escalate your response based on your scouting activity and your plan. Add your sticky traps, de-leafing, root drench, foliar sprays or knock down sprays as defined by your pest population control actions document.
For more detail on each of these treatments, you can see examples for your integrated pest management procedures in our complete white paper for Integrated Pest Management Recommendations, download the document here.
In our final chapter, Emergency Response, we will review control thresholds and example plans for a range of problems from biofilm build up to white flies and more.
Our final chapter after will describe emergency response framework and reviewing your complete plans. See you next week.
This is the fourth in a series of articles designed to introduce an integrated pest management framework for cannabis cultivation facilities. To see Part One, an overview of the plan and pest identification, click here. For Part Two, on pest monitoring and record keeping, click here. For Part Three, on preventative measures, click here. Part Five comes out next week on how to build a framework for control actions and how to monitor them. More to come!
This is Part 4: Direct Control Options
Even when the best methods are implemented and precautions are taken to protect your infrastructure, determined pests can penetrate your perimeter. Before you see crawling, hopping or flying insects, or sickly-looking plants, be sure to implement your physical protection (positive pressure airflow sealed facilities) and personal hygiene methods (shoe baths, sticky mats, & air shower entrances) to protect your crops. Equip your employees with personal protection equipment (PPE) proper gloves, masks and clothing as discussed in our last chapter, preventative measures.
Figure 1: Fungus Gnats Unleashed In A Grow Room
When things do break-out beyond your acceptable thresholds, Direct Control Options include non-chemical microbial biofungicides, microbial bioinsecticides and direct chemical control options. Lots of big scary words there, all of which are toxic even under safe application methods and when used at recommended concentrations levels. This means training in their use and protective clothing is required. Careful application of these control options is necessary so you exterminate your pests and not your people! This seems obvious, but do not just “wing it.”
These chemical elements can be applied in diluted concentration levels, manual wipe-down application, concentrated flush frequencies, or root drench applications, foliar spray mist applications, HVAC aerial diffusions and aerial knock-down sprays. You may even choose to remove badly infected plants and destroy them completely.
Use experts when you are planning for these tools. All of these methods require handling and safety precautions. Proper breathing filters, eye & skin protection, as well as disposable gowns/hazmat suits should be used when applications are performed and until the applications have dissipated to safe levels. Be careful not to co-mingle removed plant materials. Gloves become transport and infection spreaders after use.
Please also be sure to review your harvest testing requirements and what treatments are safe for your consumers and within legal limits. No one wants to have their harvest rejected due to pesticide contamination.
Figure 2: Municipal Water Treatment, RAIR Cannabis, Michigan
Clean-up after application may be required depending on the bioinsecticide or chemical that is used. Again, always ensure the safety of your employees and take precautions.
Start the application of your control options with your site map, room assignments and scout monitoring teams. Where does air flow into and within the facility? When your scouting team count logs go beyond your acceptable thresholds, here are some options for you.
Let’s begin with cleaning your irrigation and nutrient water sources. For a walk-through tutorial for incoming water treatment, humidity recovery and nutrient water recycling, please review the video tour of Water Treatment at RAIR Cannabis to see how an expert has done it.
From the IPM Planning Guide standpoint, peroxide and acid sterilizers can be used to clear irrigation water, for surface wipe-downs or as direct plant applications. We will cover those first. Caustic sterilizers require PPE for cleaning. Forgive my image here, we were just using water.
Plant interacting interfaces, i.e. surfaces, benches, walls, floors, trays, utensils, clippers, etc. should be sterilized with every use. Methods can include direct wipe-down or scrub, concentrated or diluted sprays or room vaporizers. A good example of hydrogen peroxide (H2O2) liquid would be a food grade sanitizer with 3-35% H2O2 content. Use acceptable diluted versions of these cleaners as appropriate.
Figure 3: Cleaning & Scrubbing, Where’s the PPE?
A commercial example would be Zerotol 2.0 with 27% H2O2 & their proprietary acid mix. Alternatively, you can use direct hydrogen peroxide generators from commercial sources to generate your H2O2 at various concentrations. More detailed examples are included in the complete Integrated Pest Management Guide (link at the end of this article). Establish your procedures for sterilizing your rooms and tools before you introduce plants, and describe what is to be done after every harvest and room turn. Track the cleaning materials used for your operational records. You will find this useful to track operational cost over time.
Sanitizing Acids for Surfaces & Irrigation Sources
Similar to hydrogen peroxide, hypochlorous acid (HOCl) comes in many commercial forms and can also be generated onsite using purchased generators. Commercial mix examples are UC Roots, Watermax and Athena Cleanse. They come in 0.028% to 15% concentrations. Self-generators range in output from highly precise 0.01% to 1% concentrations with more examples in the guide.
Treatment Tools
OK, so enough on cleaning preparation. Here are some tools that can be used to fight back against a pest intrusion:
Non-Chemical Microbial Biofungicide for Pathogens in Soil or Fertigation Water
Microbial fungicides are available to clear nutrient irrigation systems by minimizing pathogens and improving plant resistance to infections. Some fungicide versions target root pathogens by attacking the diseases directly. Others control or suppress common water carried challenges like pythium, rhizoctonia, phytophthora, fusarium and others. Brand names include Botanicare, Bonide, BioWorks, Actinovate, Mycostop and many more. Details covered in the guide.
Non-Chemical Microbial Bioinsecticides for Larval Stages
These biological tools attack the organisms or insects at a physical or mechanical way by breaking down the pest’s nervous system, biochemistry, or structural integrity (exoskeletons, etc.). These are engineered or living organisms (bugs to attack bugs) that are developed as targeted attacks for specific pests. Brand names are BioCeres, Botanigard, Venerate, Bio Solutions and others.
Minimal Risk Chemical Pesticides for Airborne Critters
Figure 3: Example Fungus Gnat Infestation – Royal Queen Seeds blog
Regularly approved for used in most locales, essential oils, natural acids (like citric acid) and insecticidal soap are commonly available in every hydroponic store. These work very well as safe spray “knock-down” insecticides for crawling or flying pests. Commercial examples use a proprietary mix of various oils, citric acids or isopropyl alcohol to do their task (examples in guide). Insecticidal soaps and fungicides for surface cleaning perform a similar purpose and typically use potassium salts or fatty acid mixtures.
Biochemical Pesticides
These tools are used to inhibit insect or fungal growth to acceptable levels. The multifaceted and commonly used neem oil comes in many commercial versions and is a naturally occurring pesticide extracted from the leaves and seeds of the neem tree. Example brand names are Bonide, Monterey, Triact and others. They range in concentrations from 0.9% to 70% concentrations. These oils suffocate living organisms or eliminate moisture to kill insects, spores or fungus at their initiation and throughout their lifespan.
Another option here are Azadirachtins. These act as insect growth regulators and disrupt the bugs natural evolution. Brand names are AzaGuard, AzaMax and others in the guide.
In summary, this week
We summarized some of the many pest control options available for water treatment, soil borne, intermediate or flying pests. We also covered various concentrations for these pesticide and sterilizer options. If you are not familiar with dilution ratios, %, PPM terms and how to apply the correct level of pesticide, you may find our plant science test kitchen blog on this topic of use here.
Chemical access and use should be restricted to employees familiar with their authorized application. PPE is very important to protect any employee that will come in contact with materials, liquids or vapors for chemical resources (gloves, boots, respirators, Tyvek (or equivalent protective wear) suits and eye protection or goggles.
For more detail on each of these treatments, you can see examples for your integrated pest management procedures in our complete white paper for Integrated Pest Management Recommendations, download the document here.
In our next chapter, Pest Population Control Actions, we will review control thresholds and example plans for a range of problems from biofilm build up to white flies and more. Our final chapter after that will suggest an emergency response framework and how to address pest outbreaks. See you next week.
This is the second part of a series of articles designed to introduce an integrated pest management framework for cannabis cultivation facilities. To see Part One, click here. Part Three comes out next week and covers prioritization and preventative measures. Stay tuned for more!
This is Part 2: Pest Monitoring, Record Keeping, & Communications
Begin your pest identification process with a pest scouting document. You have already mapped out your facility with locations and potential access locations. For each of these pest types and room type assignments (mothers, clone, veg, flower), identify your employee scouts, their scouting methods, scouting frequency and the type of likely pest they are to search for and count.
Insect Types and Tracking Methods
Figure 1: Example Sticky Trap Scouting Map
Insect pest types include, but are not limited to, airborne flying or crawling insects, their various egg, lymph, larvae, pupal shells or immature forms. Look for trace remnants, plant damage or feces that let you know they are present in some form. If they are at the mature jumping or flying stage, this can be harder to count, but sticky traps distributed on an even basis around your rooms can make the counting process more consistent from survey to survey.
Note airflows in your rooms and fan locations so migrations can be predicted once an infestation is located.
Insects Can Be Everywhere – Crawlers & Fliers
Insects would like to be everywhere so they come in many types from the obvious flying and crawling types to root-zone microscopic, aquatic, fungal, bacterial or biofilm based. For those of you using soil or media, root-zone insects can be beneficial by digesting and breaking down organic matter into something useful for your plant’s roots (earthworms) or harmful by feeding directly on your plant roots and sucking the life out of your plants from out-of-sight below (nematodes, maggots).
Common pests in a cannabis environment include:
White flies – Oval shaped eggs on the underside of leaves, nymphs- oval crawlers that suck on the undersides of leaves, larger stage nymphs with pupae shells as they form wings and mature white flies.
Fungus gnats – Clear eggs deposited in overly wet soil or dead plant matter. Clear or white colored larvae in the soil or media, these worm-like critters go through multiple stages of molting as they grow, eventually pupating into brown cocoons and finally small black or dark flies with clear wings that flutter around your plants and suck on your leaves.
The dreaded spider mite – Clear, hard to see eggs on the underside of your leaves. These six-legged tiny moving bubbles begin the feeding as larva, add 2 legs in the intermediate and mature nymph stages and finally the oval shaped spider mites that every grower despises, adding their webs around the tops of your plants as their nurseries suck the life out of your flowers.
Insect Transfers of Bacterial Infections
Figure 2: The Dreaded Spider Mite
Many crawlers or fliers you may discover in your grow operation do not generate fungus or bacteria on their own. However, they do routinely pick these up along the feeding way and bring them into your shop. Sap-feeding insects like leafhoppers and aphids use their needle mouths to pierce your leaves to suck on the sap that is nourishing your greenery. These insects consume the fluids and transfer bacteria as they feed. Whiteflies fit into this category of leaf sucking bacteria carrying pests. These pests can make your healthy grow rooms look blotchy with color drained out of your canopy.
Obvious symptoms of these flying/hopping pests are sticky leaves, black fungus mold, or yellowing leaves that show up at the bottom of your plants and work their way upward as the infestation progresses. Leaf curling or plant wilting will be visible in the more advanced stages of these pests.
As if crawlers were not bad enough, invisible fungus and bacteria that get into your water supplies can be the worst challenges of any grow.
Water Sourced Bacteria
Baseline testing of your feed water is critical for any facility. This is true whether you are using surface water, well water or municipal water. Please see the water tutorials on the AEssenseGrows website for details on how to test your water sources and what to look for in the mineral content.
Regardless of your water source, bacteria can be present directly in your water supply, or it can be introduced from infected plant materials from one of your suppliers. Pythium, fusarium and the latest plague, hop latent viroid, are some of the most common threats that attack your plants from your water or soil sources. These can come from your wells, feed lines or plant materials.
Reverse osmosis (RO) is a typical method to clear water of most pathogens and bacteria using water that is pressed through filters with very small membrane apertures. These small openings usually stop impurities, salts and microorganisms. Of course, these systems come in many different types and they have to be maintained to keep their performance quality. Don’t take shortcuts on your RO system.
Once your water source is clean, strict hygiene procedures for tools, equipment and plumbing are the best way to minimize these threats to your plants downstream from your water source. These cleaning efforts are not a guarantee. Pests can still get into even the best facilities. Symptoms of these maladies vary, but root rot, stunted growth, wilting, discolored roots or leaves, and in some cases, the quick death of your plants is possible depending on the critter.
Use your scouting regimen and your data mapping to locate infestations before they expand and damage your facility. Isolate outbreaks and take appropriate measures to address the pests. We will give you suggestions on prioritization and preventative measures to take in the next chapter.
Figure 3: Example Pythium Brown Roots
Pythium is one of the most commonly harbored soil or water carried pests. When it is present and gets into your plants through cuts, natural openings, root surfaces or leaves on weakened plants, it can be devastating. In hydroponic systems, dirty looking brown roots evolve into full root rot if not addressed. Pythium is often the cause. In soil operations, pythium often shows up as wilting or yellowing patches on leaves.
Your lab testing partners are your friends when it comes to bacterial or fungal infections. Many diseases can resemble one another. It is not hard to misdiagnose environmental stress such as overheating or overwatering for a bacterial problem. Test results are necessary to accurately diagnose a problem.
Truly Airborne Molds & Mildews
Pythium and fusarium are not just present in water. They can also be airborne. Grey mold (botrytis) and powdery mildew are also common airborne pests. Proper humidity, air movement, air filtration and sterilization using HEPA (High-Efficiency Particulate Air) filters, activated carbon filters (also filter smells) and UV light sterilization can minimize these problems in your grow. Powdery mildew is the primary evil spore in this category. Airflow and regular cleaning to discourage fungal growth is the best way to limit these pests.
In conclusion, this week
Now that we have talked about identification (and clearly, this is not an exhaustive list), we will move into how to build in the cultural methods to prevent these problems from taking hold and ruining your business. In later chapters, we will dive into prioritization, treatment and control options for infestations, finally moving into control actions and emergency response.
Your integrated management response is how you pull all of this together and use your IPM procedures to increase your profitability. For the complete white paper on Integrated Pest Management Recommendations, download the document here.
Part three comes out next week and will delve into the world of Preventative Measures. Stay tuned for more!
On August 11, PathogenDx announced that they received an AOAC Performance Tested Methods Certificate for their QuantX total yeast and mold test. Six days later, on August 17, Medicinal Genomics announced that AOAC approved their PathoSEEK 5-Color Aspergillus Multiplex Assays under the same AOAC Performance Tested Methods program.
Both assays are specifically designed with cannabis and hemp testing in mind and designed to expedite and simplify microbiological testing. PathogenDx’s QuantX quantifies the total amount of yeast and mold in a sample while also measuring against safety standards.
In addition to the total yeast and mold count test, PathogenDx has also introduced a 96-well plate, improved sample preparation and new data reporting with a custom reporting portal for compliance testing.
The Medicinal Genomics platform can detect four species, including A. flavus, A. fumigatus, A. niger, and A. terreus in both flower and infused edibles. The PathoSEEK microbial testing platform uses a PCR-based assay and provides an internal plant DNA control for every reaction.
This technique verifies the performance of the assay when detecting pathogens, allegedly minimizing false negative results commonly due to set up errors and experimental conditions.
AOAC International is a standards organization that works in the cannabis testing space through their CASP program to evaluate and approve standard testing methods for the industry.
In this “Leaders in Cannabis Testing” series of articles, Green interviews cannabis testing laboratories and technology providers that are bringing unique perspectives to the industry. Particular attention is focused on how these businesses integrate innovative practices and technologies to navigate a rapidly changing landscape of regulatory constraints and B2B demand.
PathogenDx is an Arizona-based provider of microbial testing technologies. Since their inception in 2014, they have broadened their reach to 26 states in the US. In addition to cannabis product testing, PathogenDx also provides technologies for food safety testing, environmental testing and recently started offering human diagnostics testing to support COVID-19 response efforts.
We interviewed Milan Patel, CEO and co-founder of PathogenDx. Milan founded PathogenDx as a spin-off from one of his investments in a clinical diagnostics company testing for genetic markers in transplant organs. Prior to PathogenDx, Milan worked in finance and marketing at Intel and later served as CFO at Acentia (now Maximus Federal).
Aaron Green: What’s the history of PathogenDx?
Milan Patel: PathogenDx was effectively a spin-off of a clinical diagnostics company that my partner Dr. Mike Hogan, the inventor of the technology, had founded when he was a professor at the University of Arizona, but previously at Baylor Medical College back in 2002. I had invested in the company back then and I had realized that his technology had a broad and wide sweeping impact for testing – not just for pathogens in cannabis specifically, but also for pathogens in food, agriculture, water and even human diagnostics. In the last 14 months, this became very personal for every single person on the planet having been impacted by SARS-CoV-2, the viral pathogen causing Covid-19. The genesis of the company was just this, that human health, food and agricultural supply, and the environment has and will continue to be targeted by bacterial, fungal and viral pathogens impacting the safety and health of each human on the planet.
We founded PathogenDx and we pivoted the company from its original human organ transplant genetics market scope into the bigger markets; we felt the original focus was too niche for a technology with this much potential. We licensed the technology, and we repurposed it into primarily cannabis. We felt that achieving commercial success and use in the hands of cannabis testing labs at the state level where cannabis was first regulated was the most logical next step. Ultimately, our goal was and is to move into markets that are approved at the federal regulatory side of the spectrum, and that is where we are now.
Green: What year was that?
Milan Patel, CEO and Co-Founder of PathogenDx Photo credit: Michael Chansley
Patel: 2014.
Green: So, PathogenDx started in cannabis testing?
Patel: Yes, we started in cannabis testing. We now have over 100 labs that are using the technology. There is a specific need in cannabis when you’re looking at contamination or infection.
In the case of contamination on cannabis, you must look for bacterial and fungal organisms that make it unsafe, such as E. coli, or Salmonella or Aspergillus pathogens. We’re familiar with recent issues like the romaine lettuce foodborne illness outbreaks at Chipotle. In the case of fungal organisms such as Aspergillus, if you smoke or consume contaminated cannabis, it could have a huge impact on your health. Cannabis regulators realized that to ensure public health and safety there was more than just one pathogen – there were half a dozen of these bugs, at a minimum, that could be harmful to you.
The beauty of our technology, using a Microarray is that we can do what is called a multiplex test, which means you’re able to test for all bacterial and fungal pathogens in a single test, as opposed to the old “Adam Smith” model, which tests each pathogen on a one-by-one basis. The traditional approach is costly, time consuming and cumbersome. Cannabis is such a high value crop and producers need to get the answer quickly. Our tests can give a result in six hours on the same day, as opposed to the two or three days that it takes for these other approved methods on the market.
Green: What is your business model? Is there equipment in addition to consumables?
Patel: Our business model is the classic razor blade model. What that means is we sell equipment as well as the consumables – the testing kits themselves.
The PathogenDx technology uses standard, off-the-shelf lab equipment that you can find anywhere. We didn’t want to make the equipment proprietary so that a lab has to buy a specific OEM branded product. They can use almost any equipment that’s available commercially. We wanted to make sure that labs are only paying a fraction of the cost to get our equipment, as opposed to using other vendors. Secondly, the platform is open-ended, meaning it’s highly flexible to work with the volumes that different cannabis labs see daily, from high to low.
One equipment set can process many different types of testing kits. There are kits for regulated testing required by states, as well as required environmental contamination.
Green: Do you provide any in-house or reference lab testing?
Patel: We do. We have a CLIA lab for clinical testing. We did this about a year ago when we started doing COVID testing.
We don’t do any kind of in-house reference testing for cannabis, though we do use specific reference materials or standards from Emerald Scientific, for example, or from NCI. Our platform is all externally third-party reference lab tested whether it’s validated by our external cannabis lab customers or an independent lab. We want our customers to make sure that the actual test works in their own hands, in their own facility by their own people, as opposed to just shrugging our shoulders and saying, “hey, we’ve done it ourselves, believe us.” That’s the difference.
Green: Can you explain the difference between qPCR and endpoint PCR?
Patel: The difference between PathogenDx’s Microarray is it uses endpoint PCR versus qPCR (quantitative real time PCR). Effectively, our test doesn’t need to be enriched. Endpoint PCR delivers a higher level of accuracy, because when it goes to amplify that target DNA, whether it’s E. coli, Salmonella or Aspergillus pieces, it uses all the primer reagent to its endpoint. So, it amplifies every single piece of an E. Coli (for example) in that sample until the primer is fully consumed. In the case of qPCR, it basically reaches a threshold and then the reaction stops. That’s the difference which results in a much greater level of accuracy. This provides almost 10 times greater sensitivity to identify the pathogen in that sample.
The second thing is that we have separated out how the amplified sample hybridizes to the probe. In the case of our assay, we have a microarray with a well in it and we printed the actual probe that has the sequence of E. coli in there, now driving 100% specificity. Whereas in the qPCR, the reaction is not only amplifying, but it’s also basically working with the probe. So, in that way, we have a higher level of efficiency in terms of specificity. You get a definite answer exactly in terms of the organism you’re looking for.
In terms of an analogy, let’s take a zip code for example which has the extra four digits at the end of it. In the case of endpoint PCR, we have nine digits. We have our primer probes which represent the standard five digits of a zip code, and the physical location of the probe itself in the well which serves as the extra four digits of that zip code. The analyte must match both primary and secondary parts of the nine-digit zip code for it to lock in, like a key and a lock. And that’s the way our technology works in a nutshell.
Endpoint PCR is completely different. It drives higher levels of accuracy and specificity while reducing the turnaround time compared to qPCR – down to six hours from sample to result. In qPCR, you must enrich the sample for 24 to 48 hours, depending on bacteria or fungus, and then amplification and PCR analysis can be done in one to three hours. The accuracies and the turnaround times are the major differences between the endpoint PCR and qPCR.
Green: If I understand correctly, it’s a printed microarray in the well plate?
Patel: That’s correct. It’s a 96-well plate, and in each well, you’ve now printed all the probes for all targets in a single well. So, you’re not running more than one well per target, or per organism like you are for qPCR. You’re running just one well for all organisms. With our well plates, you’re consuming fewer wells and our patented foil-cover, you only use the wells you need. The unused wells in the well plate can be used in future tests, saving on costs and labor.
Green: Do you have any other differentiating IP?
The PathogenDx Microarray
Patel: The multiplex is the core IP. The way we process the raw sample, whether it’s flower or non-flower, without the need for enrichment is another part of the core IP. We do triplicate probes in each well for E. Coli, triplicate probes for Salmonella, etc., so there are three probes per targeted organism in each of the wells. We’re triple checking that you’re definitively identifying that bug at the end of the day. This is the cornerstone of our technology.
We were just approved by the State of New York, and the New York Department of Health has 13 different organisms for testing on cannabis. Think about it: one of the most rigorous testing requirements at a state level – maybe even at a federal level – and we just got approved for that. If you had to do 13 organisms separately, whether it’s plate culture or qPCR, it would become super expensive and very difficult. It would break the very backs of every testing lab to do that. That’s where the multiplexing becomes tremendously valuable because what you’re doing is leveraging the ability to do everything as a single test and single reaction.
Green: You mentioned New York. What other geographies are you active in?
Patel: We’re active in 26 different states including the major cannabis players: Florida, Nevada, California, Arizona, Michigan, New York, Oklahoma, Colorado and Washington – and we’re also in Canada. We’re currently working to enter other markets, but it all comes down to navigating the regulatory process and getting approval.
We’re not active currently in other international markets yet. We’re currently going through the AOAC approval process for our technology and I’m happy to say that we’re close to getting that in the next couple of months. Beyond that, I think we’ll scale more internationally.
I am delighted to say that we also got FDA EUA federal level authorization of our technology which drives significant credibility and confidence for the use of the technology. About a year ago, we made a conscious choice to make this technology federally acceptable by going into the COVID testing market. We got the FDA EUA back on April 20, ironically. That vote of confidence by the FDA means that our technology is capable of human testing. That has helped to create some runway in terms of getting federalized with both the FDA and the USDA, and certification by AOAC for our different tests.
Green: Was that COVID-19 EUA for clinical diagnostics or surveillance?
Patel: It was for clinical diagnostics, so it’s an actual human diagnostic test.
Green: Last couple of questions here. Once you find something as a cannabis operator, whether its bacteria or fungus, what can you do?
Patel: There are many services that are tied into our ecosystem. For example, we work with Willow Industries, who does remediation.
There’s been a lot of criticism around DNA based technology. It doesn’t matter if it’s qPCR or endpoint PCR. They say, “well, you’re also including dead organisms, dead DNA.” We do have a component of separating live versus dead DNA with a biomechanical process, using an enzyme that we’ve created, and it’s available commercially. Labs can test for whether a pathogen is living or dead and, in many cases, when they find it, they can partner with remediation companies to help address the issue at the grower level.
Another product we offer is an EnviroX test, which is an environmental test of air and surfaces. These have 50 pathogens in a single well. Think about this: these are all the bad actors that typically grow where soil is – the human pathogens, plant pathogens, powdery mildew, Botrytis, Fusarium – these are very problematic for the thousands of growers out there. The idea is to help them with screening technology before samples are pulled off the canopy and go to a regulated lab. We can help the growers isolate where that contamination is in that facility, then the remediation companies can come in, and help them save their crop and avoid economic losses.
Green: What are you most interested in learning about?
Patel: I would prefer that the cannabis industry not go through the same mistakes other industries have gone through. Cannabis started as a cottage industry. It’s obviously doubled every year, and as it gets scaled, the big corporations come in. Sophistication, standards, maturity all help in legitimacy of a business and image of an industry. At the end of the day, we have an opportunity to learn from other industries to really leapfrog and not have to go through the same mistakes. That’s one of the things that’s important to me. I’m very passionate about it.
One thing that I’ll leave you with is this: we’re dealing with more bugs in cannabis than the food industry. The food industry is only dealing with two to four bugs and look at the number of recalls they are navigating – and this is a multi-billion-dollar industry. Cannabis is still a fraction of that and we’re dealing with more bugs. We want to look ahead and avoid these recalls. How do you avoid some of the challenges around antimicrobial resistance and antibiotic resistance? We don’t want to be going down that road if we can avoid it and that’s sort of a personal mission for myself and the company.
Cannabis itself is so powerful, both medicinally as well as recreationally, and it can be beneficial for both consumers and industry image if we do the right things, and avoid future disasters, like the vaping crisis we went through 18 months ago because of bad GMPs. We must learn from those industries. We’re trying to make it better for the right reasons and that’s what’s important to me.
Green: Okay, great. That concludes the interview. Thank you, Milan.
Patel: Thank you for allowing me to share my thoughts and your time, Aaron.
The journal Frontiers in Plant Science recently shared an important article from researchers at Simon Fraser University in British Columbia, highlighting the “Pathogens and Molds Affecting Production and Quality of Cannabis Sativa.”
As a chemist focused on the science of preventing and mitigating mold in greenhouse and indoor cannabis grow facilities, this piece was fascinating to me. Like many others, it details and explains prevalent mold like Penicillium, Cladosporium and Aspergillus – things I see in grows every day.
But wait, there’s more fungi
The research and resulting article also brought up another type of fungi – endophytic mold. Endophytic mold usually lives symbiotically with plants, or is at least beneficial for both plant and fungi.
But not always.
In the past, the industry has believed that damaging mold spores were found on the outside of the flower. When moved, that flower would release the spores and send them flying – often creating massive cross-contamination issues for indoor grows.
Hope Jones, PhD, CEO of Adivina & ECS
“While cannabis is an incredibly powerful plant in terms of its medicinal properties, it is unfortunately highly susceptible to many pest and pathogens,” says Hope Jones, PhD, CEO, Adivina & ECS. “And it is this susceptibility that is so challenging to many inexperienced or undisciplined grow operations.”
Now, however, we know that there’s another culprit to add to the list: the inner parts of the plant can also be a source of endophytic cross contamination and mold.
Since it grows inside of the plant, this fungus creates high spore counts that can cross contaminate from outside, into the flower.
Treating mold in a facility
Here’s the good news:
This seemingly bad news – that there’s a new fungus to worry about, and it is inside the flower – may actually help cannabis grows struggling with mold, and those who are following the proper protocols already.
A petri dish of mold growth from tested cannabis Photo credit: Steep Hill
Effective mitigation protocols can include things like treating HVAC systems, controlling humidity, using products like chlorine dioxide to treat irrigation lines, enforcing protective clothing and shoe covers for employees, reducing the amount of in-and-out for employees around grow rooms.
These are important upstream and environmentally-focused integrated pest management (IPM) programs that will usually keep facilities clean and relatively mold-free.
But if these programs are in place, and there’s still an issue, Endophytic fungi may be to blame.
If you are having ongoing mold issues but have ruled out cross-contamination and a facility without proper protocol, look to the mother plant.
“Small mistakes in agricultural practices are amplified with cannabis,” Dr. Jones continues. “And today’s propagation practices of traditional cloning add to this vulnerability. Cannabis is an annual plant and by keeping mothers in a perpetual state of vegetative growth for years, and taking repetitive cuttings produces clones in a highly stressed state. This stressed state diminishes genetic potential and weakens a plant’s ability to fight disease and pests.”
Testing for and addressing endophytic fungi
If these concerns are ringing a bell, remember, there is also a way to test for Endophytic mold.
Checking cuttings from suspected mother plants over a period of time is the best way to see if the Endophytic mold is present.
A section of the mother plant cutting is placed into a solution (for example, as outlined by the article, a very concentrated hypochlorite followed by 70% Ethanol) that will kill all of the microorganisms that are present on the surface of the plant tissues.
A large tissue culture facility run in the Sacramento area that produces millions of nut and fruit trees clones a year.
From there, an unadulterated dissection of the internal tissues can be extracted and cultured for quantification and identification of endophytic fungi.
“Tissue culture offers a form of genetic rebooting returning the plant to its natural genetic potential and thereby strengthening its natural ability to defend against environment assault,” says Dr. Jones. “It also allows the breeder to conduct pathogenic disease testing which provides the entire industry with a higher level of scientific certainty and analysis.”
If you find this mold inside of the mother plant, your facility’s mold problem could be a systemic issue, not an environmental one.
If you do find that Endophytic mold is causing issues, of course, you may have to destroy the mother plant.
This should not mean the end of a strain. Tissue culture on a cutting is an option that can eliminate the unwanted fungi and save the genetics. Using those genetics to regrow a mother will start fresh and avoid the intrinsic mold that was plaguing the strain prior.
Growing knowledge
The practice of checking mother plants for Endophytic mold is not yet commonplace in cannabis, but the hemp business is leading the way.
They’re testing to create very clean plants, so you don’t have issues during cultivation.
Major growers in the U.S. could save millions in lost harvests with mold mitigation. If your current IPM program isn’t doing the trick, you may want to follow in hemp’s footsteps and look inside the plant.
I think that we need to start changing the terminology around the hazards associated with cannabis from food safety hazards to product safety hazards. These hazards have not only been associated with harmful effects for those that ingest cannabis infused products, but also for those that consume the cannabis products in other ways such as inhalation (vaping or smoking). So, when we refer to these hazards as food safety hazards, the immediate thought is edibles, which misleads cultivators, manufacturers and consumers to have a false sense of security around the safety of products that are consumed in other ways.
By standardizing and documenting safety procedures, manufacturers mitigate the risk of cannabis-specific concerns
There are several product safety hazards that have been associated with cannabis. These hazards can become a public health problem if not controlled as they could harm the consumer, regardless of the method of consumption.
Let’s take a look at the different types of hazards associated cannabis:
Biological Hazards refer to those microorganisms that can cause illness to the consumer of a product that contain them. They are not visible to the naked eye and are very dangerous when their metabolic by-products (toxins) are ingested or their spores are inhaled. The symptoms for illnesses caused by these microorganisms will vary. Consumers may experience gastrointestinal discomfort (vomiting, diarrhea), headaches, fever and other symptoms. The ingestion of these pathogens, allergens or their by-products may lead to death, if the illness is not treated on time or if the consumer of the product is immunocompromised. In addition, the inhalation of mold spores when smoking cannabis products, can lead to lung disease and death. Some of the biological hazards associated with cannabis are: Salmonella sp., E. coli, Clostridium botulinum, Aspergillus sp. and Penicillium sp.
Chemical Hazards refer to those chemicals that can be present in the plant or finished product due to human applications (pesticides), operational processes (extraction solvents and cleaning chemicals), soil properties (heavy metals), environmental contamination (radiological chemicals) or as a result of occurring naturally (mycotoxins and allergens). Consuming high concentrations of cleaning chemicals in a product can lead to a wide range of symptoms from mild rash, burning sensation in the oral-respiratory system, gastrointestinal discomfort or death. In addition, long term exposure to chemicals such as pesticides, heavy metals, radiological contaminants and mycotoxins may lead to the development of cancers.
Physical Hazards refer to those foreign materials that may be present in the plant or finished product. Foreign materials such as rocks, plastics or metals can cause harm to the consumer by chipping teeth or laceration of the mouth membranes (lips, inner cheeks, tong, esophagus, etc.) In the worst-case scenario, physical hazards may lead to choking, which can cause death due to asphyxiation.
These hazards can be prevented, eliminated or reduced to an acceptable level when foundational programs (Good Agricultural/Cultivation Practices, Good Manufacturing Practices, Allergen Management Program, Pest Control, etc.) are combined with a Food [Product] Safety Plan. These lead to a Food [Product] Safety Management System that is designed to keep consumers safe, regardless of the method of consumption.
I have been studying microorganisms for over 35 years, and the elusive critters still fascinate me! Here in Microbiology 101, I write about the foundation of knowledge on which all microbiologists build. You may have a general interest in microbiology or have concerns in your operation. By understanding microbiology, you understand the diversity of microorganisms, their source, control of microorganisms and their importance.
Part 1
The term microbiology covers every living being we cannot see with the naked eye. The smallest microbe is a virus. Next in size are the bacteria, then yeast and mold cells, and the largest microbes are the protozoans. The tiny structure of a virus may be important in the plant pathology of cannabis, but will not grow in concentrates or infused products. A virus is not living, until it storms the gate of a living cell and overtakes the functions within the cell. Viruses are the number one cause of foodborne illness, with the number one virus called Norovirus. Think stomach flu. Think illness on cruise ships. Viruses are a food service problem and can be prevented by requiring employees to report sickness, have good personal hygiene including good hand washing, and, as appropriate, wear gloves. Following Good Manufacturing Practices (GMPs) is critical in preventing the transfer of viruses to a product where the consumer can be infected.
The petri dishes show sterilization effects of negative air ionization on a chamber aerosolized with Salmonella enteritidis. The left sample is untreated; the right, treated. Photo courtesy of USDA ARS & Ken Hammond
The largest microbial cell is the protozoan. They are of concern in natural water sources, but like viruses, will not grow in cannabis products. Control water quality through GMPs, and you control protozoans. Viruses and protozoans will not be further discussed here. Bacteria, yeast and mold are the focus of further discussion. As a food microbiologist, my typical application of this information is in the manufacturing of food. Because Microbiology 101 is a general article on microbiology, you can apply the information to growing, harvesting, drying, manufacture of infused products and dispensing.
It is not possible to have sterile products. Even the canning process of high temperature for an extended time allows the survival of resistant bacterial spores. Astronauts take dehydrated food into space, and soldiers receive MREs; both still contain microbes. Sterility is never the goal. So, what is normal? Even with the highest standards, it is normal to have microbes in your products. Your goal is to eliminate illness-causing microorganisms, i.e. pathogens. Along the way, you will decrease spoilage microbes too, making a product with higher quality.
Petri dish containing the fungus Aspergillus flavus. It produces carcinogenic aflatoxins, which can contaminate foods and cause an invasive fungal disease. Photo courtesy of USDA ARS & Peggy Greb.
Yeast and mold were discussed on CIJ in a previous article, Total Yeast & Mold Count: What Cultivators & Business Owners Need to Know. Fuzzy mold seen on the top of food left in the refrigerator too long is a quality issue, not a safety issue. Mold growth is a problem on damaged cannabis plants or cuttings and may produce mycotoxin, a toxic chemical hazard. Following Good Agricultural Practices (GAPs) will control mold growth. Once the plant is properly dried, mold will not grow and produce toxin. Proper growing, handling and drying prevents mycotoxins. Like mold, growth of yeast is a quality issue, not a safety issue. As yeast grow, they produce acid, alcohol and carbon dioxide gas. While these fermentation products are unwanted, they are not injurious. I am aware that some states require cannabis-infused products to be alcohol-free, but that is not a safety issue discussed here.
What are the sources of microorganisms?
People. Employees who harvest cannabis may transfer microorganisms to the plant. Later, employees may be the source of microbes at the steps of trimming, drying, transfer or portioning, extract processing, infused product manufacture and packaging.
Ingredients, Supplies and Materials. Anything you purchase may be a source of microorganisms. Procure quality merchandise. Remember the saying, “you get what you pay for.”
Environment. Starting with the outdoors, microbes come from wind, soil, pests, bird droppings and water. When plants are harvested outdoors or indoors, microbes come from the tools and bins. Maintain clean growing and harvesting tools in good working condition to minimize contamination with microbes. For any processing, microbes come from air currents, use of water, and all surfaces in the processing environment from dripping overhead pipes to floor drains and everything in between.
In Part 2 I will continue to discuss the diversity of microorganisms, and future articles will cover Hazard Analysis and Critical Control Points (HACCP) and food safety in more detail. What concerns do you have at each step of operations? Are you confident in your employees and their handling of the product? As each state works to ensure public health, cannabis-infused products will receive the same, if not more, scrutiny as non-cannabis food and beverages. With an understanding and control of pathogens, you can focus on providing your customers with your highest quality product.
Editor’s note: This article should serve as a foundation of knowledge for yeast and mold in cannabis. Beginning in January 2018, we will publish a series of articles focused entirely on yeast and mold, discussing topics such as TYMC testing, preventing yeast and mold in cultivation and treatment methods to reduce yeast and mold.
Cannabis stakeholders, including cultivators, extractors, brokers, distributors and consumers, have been active in the shadows for decades. With the legalization of recreational adult use in several states, and more on the way, safety of the distributed product is one of the main concerns for regulators and the public. Currently, Colorado1, Nevada and Canada2 require total yeast and mold count (TYMC) compliance testing to evaluate whether or not cannabis is safe for human consumption. As the cannabis industry matures, it is likely that TYMC or other stringent testing for yeast and mold will be adopted in the increasingly regulated medical and recreational markets.
The goal of this article is to provide general information on yeast and mold, and to explain why TYMC is an important indicator in determining cannabis safety.
Yeast & Mold
Photo credit: Steep Hill- a petri dish of mold growth from tested cannabis
Yeast and mold are members of the fungi family. Fungus, widespread in nature, can be found in the air, water, soil, vegetation and in decaying matter. The types of fungus found in different geographic regions vary based upon humidity, soil and other environmental conditions. In general, fungi can grow in a wide range of pH environments and temperatures, and can survive in harsh conditions that bacteria cannot. They are not able to produce their own food like plants, and survive by breaking down material from their surroundings into nutrients. Mold cannot thrive in an environment with limited oxygen, while yeast is able to grow with or without oxygen. Most molds, if grown for a long enough period, can be detected visually, while yeast growth is usually detected by off-flavor and fermentation.
Due to their versatility, it is rare to find a place or surface that is naturally free of fungi or their spores. Damp conditions, poor air quality and darker areas are inviting environments for yeast and mold growth.
Cannabis plants are grown in both indoor and outdoor conditions. Plants grown outdoors are exposed to wider ranges and larger populations of fungal species compared to indoor plants. However, factors such as improper watering, the type of soil and fertilizer and poor air circulation can all increase the chance of mold growth in indoor environments. Moreover, secondary contamination is a prevalent risk from human handling during harvest and trimming for both indoor and outdoor-grown cannabis. If humidity and temperature levels of drying and curing rooms are not carefully controlled, the final product could also easily develop fungi or their growth by-product.
What is TYMC?
TYMC, or total yeast and mold count, is the number of colony forming units present per gram of product (CFU/g). A colony forming unit is the scientific means of counting and reporting the population of live bacteria or yeast and mold in a product. To determine the count, the cannabis sample is plated on a petri dish which is then incubated at a specific temperature for three to five days. During this time, the yeast and mold present will grow and reproduce. Each colony, which represents an individual or a group of yeast and mold, produces one spot on the petri dish. Each spot is considered one colony forming unit.
Why is TYMC Measured?
TYMC is an indicator of the overall cleanliness of the product’s life cycle: growing environment, processing conditions, material handling and storage facilities. Mold by itself is not considered “bad,” but having a high mold count, as measured by TYMC, is alarming and could be detrimental to both consumers and cultivators.
Aspergillus species niger Photo: Carlos de Paz, Flickr
The vast majority of mold and yeast present in the environment are indeed harmless, and even useful to humans. Some fungi are used commercially in production of fermented food, industrial alcohol, biodegradation of waste material and the production of antibiotics and enzymes, such as penicillin and proteases. However, certain fungi cause food spoilage and the production of mycotoxin, a fungal growth by-product that is toxic to humans and animals. Humans absorb mycotoxins through inhalation, skin contact and ingestion. Unfortunately, mycotoxins are very stable and withstand both freezing and cooking temperatures. One way to reduce mycotoxin levels in a product is to have a low TYMC.
Aspergillus flavus on culture. Photo: Iqbal Osman, Flickr
Yeast and mold have been found to be prevalent in cannabis in both current and previous case studies. In a 2017 UC Davis study, 20 marijuana samples obtained from Northern California dispensaries were found to contain several yeast and mold species, including Cryptococcus, Mucor, Aspergillus fumigatus, Aspergillus niger, and Aspergillus flavus.3 The same results were reported in 1983, when marijuana samples collected from 14 cannabis smokers were analyzed. All of the above mold species in the 2017 study were present in 13 out of 14 marijuana samples.4
Aspergillus species niger, flavus, and fumigatus are known for aflatoxin production, a type of dangerous mycotoxin that can be lethal.5 Once a patient smokes and/or ingests cannabis with mold, the toxins and/or spores can thrive inside the lungs and body.6, 7 There are documented fatalities and complications in immunocompromised patients smoking cannabis with mold, including patients with HIV and other autoimmune diseases, as well as the elderly.8, 9, 10, 11
For this reason, regulations exist to limit the allowable TYMC counts for purposes of protecting consumer safety. At the time of writing this article, the acceptable limit for TYMC in cannabis plant material in Colorado, Nevada and Canada is ≤10,000 CFU/g. Washington state requires a mycotoxin test.12 California is looking into testing for specific Aspergillus species as a part of their requirement. As the cannabis industry continues to grow and advance, it is likely that additional states will adopt some form of TYMC testing into their regulatory testing requirements.
Centre for Disease control and prevention. 2004 Outbreak of Aflatoxin Poisoning – Eastern and central provinces, Kenya, Jan – July 2004. Morbidity and mortality weekly report.. Sep 3, 2004: 53(34): 790-793
Cescon DW, Page AV, Richardson S, Moore MJ, Boerner S, Gold WL. 2008. Invasive pulmonary Aspergillosis associated with marijuana use in a man with colorectal cancer. Diagnosis in Oncology. 26(13): 2214-2215.
Szyper-Kravits M, Lang R, Manor Y, Lahav M. 2001 Early invasive pulmonary aspergillosis in a leukemia patient linked to aspergillus contaminated marijuana smoking. Leukemia Lymphoma 42(6): 1433 – 1437.
Verweii PE, Kerremans JJ, Voss A, F.G. Meis M. 2000. Fungal contamination of Tobacco and Marijuana. JAMA 2000 284(22): 2875.
Ruchlemer R, Amit-Kohn M, Raveh D, Hanus L. 2015. Inhaled medicinal cannabis and the immunocompromised patient. Support Care Cancer. 23(3):819-822.
McPartland JM, Pruitt PL. 1997. Medical Marijuana and its use by the immunocompromised. Alternative Therapies in Health and Medicine. 3 (3): 39-45.
Hamadeh R, Ardehali A, Locksley RM, York MK. 1983. Fatal aspergillosis associated with smoking contaminated marijuana, in a marrow transplant recipient. Chest. 94(2): 432-433.
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