Tag Archives: cultivate

plantsjacques

Optimizing Your LED Spectrum for Leaf Surface Temperature

By Andrew Myers
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plantsjacques

Every detail counts at an indoor grow facility. Indoor growers have complete control over nearly every aspect of their crop, ranging from light intensity to air circulation. Among the most important factors to regulate is temperature. While ambient air temperature is critical, growers will also want to measure leaf surface temperature (LST).

To illustrate, let’s say you keep your living room at a cozy 76 degrees. Then, if you place a thermometer under your tongue – your body is (hopefully) not at 76 degrees but is likely between a healthy temperature of 97 to 99 degrees.

A similar story can be told for cannabis plants grown indoors. A grow facility’s ambient air is often different than the plants’ LST. Finding an ideal LST for plant growth can be complex, but modern technology, including spectrally tunable LED grow lights, can simplify monitoring and maintaining this critical aspect.

Why Should Growers Care About LST?

Temperature plays a pivotal role in plant health. Many biochemical reactions contributing to growth and survival only occur within an ideal temperature range. If temperatures dip or spike dramatically, growers may witness inhibited growth, plant stress or irreversible damage to their crops.

The leaf is among the most important plant structures as it’s where most metabolic processes happen. Therefore, finding an optimum LST can improve growth rate and the production of metabolites such as pigments, terpenes, resins and vitamins.

Because many plants rely on their leaves for survival, it makes sense that leaves have their own temperature regulation system. Evaporation through pores in the leaf – known as stomata – can cool the plant through a process called transpiration. Up to 90% of water absorbed is used for transpiration, while 10% is used for growth.

The efficacy of transpiration is determined by the vapor pressure deficit (VPD), which refers to the relative humidity in the ambient air compared to the relative humidity in the leaf. If relative humidity is low, the VPD can be too high, which may cause plants to have withered, leathery leaves and stunted growth. On the other hand, a low VPD correlates to high relative humidity, and can quickly result in disease and mineral deficiencies. Higher humidity often results in a higher LST as transpiration may not be as effective.

When it comes to LST, growers should follow these basic guidelines:

  • Most cannabis plants’ LST should fall between 72 and 86 degrees – generally warmer than the ambient air.
  • LST varies depending on individual cultivar. For example, plants that have evolved in colder climates can generally tolerate cooler temperatures. The same can be said for those evolved in equatorial or temperate climates.
  • CO2 availability also plays a role in LST; CO2 generally raises the target temperature for photosynthesis.

How Does Light Spectrum Affect LST?

We know that CO2 concentration, specific genetic markers and ambient temperature all play an important role in moderating LST. But another important factor at an indoor grow is light spectrum – especially for those using spectrally tunable LEDs. Growers will want to optimize their light spectrum to provide their crop with ideal conditions.

A combination of red and blue wavelengths is shown to have the greatest impact on photosynthesis and, thus, LST. Photons found along the green and yellow wavelengths may not be absorbed as efficiently and instead create heat.

solsticegrowop_feb
Indoor cultivator facilities often use high powered lights that can give off heat

Optimized light spectrums – those with an appropriate balance between red and blue light – create more chemical energy instead of heat, thereby resulting in a lower LST. Using fixtures that are not spectrally tuned for plant growth, on the other hand, can waste energy and ultimately contribute to a higher LST and ambient temperature, negatively affecting plant growth. Consequently, measuring LST doesn’t only indicate ideal growing conditions but also indirectly illustrates the efficiency of your grow lights.

LED fixtures already run at a lower temperature than other lighting technologies, so indoor growers may need to raise the ambient temperature at their grow facilities to maintain ideal LST. Switching to spectrally tuned LEDs may help growers cut down on cooling and dehumidifying costs, while simultaneously improving crop health and productivity.

What’s the Best Way to Measure LST?

There are several tools available for growers to measure LST, ranging from advanced probes to specialty cameras. However, many of these tools provide a reading at a specific point, rather than the whole leaf, leading to some inaccuracies. Temperature can dramatically vary across the leaf, depending if parts are fully exposed to the light or in the shadows.

Investing in a forward-looking infrared camera (FLIR) gives indoor growers a more accurate picture of LST and light efficiency. That being said, growers should not only measure leaves at the top of the plant, but across the middle and bottom of the plant as well. That way, growers receive a complete snapshot of growing conditions and can make changes as needed.

At an indoor grow facility, it’s not enough to only measure ambient room temperature. Of course, this aspect is important, but it will paint an incomplete picture of plant health. Measuring LST gives growers nuanced insights as to how plants respond to their environment and how they can better encourage resilient, healthy growth.

Using spectrally tunable LEDs makes achieving LST easier and more cost-effective. Lights with optimized spectrums for plant growth ensure no energy is wasted – resulting in superior performance and efficiency.

Preventing Mold & Fungus in Cannabis with Data Analytics

By Leighton Wolffe
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Cannabis legalization has taken the United States by storm, with 33 states approved for medicinal cannabis use — 11 of which are also approved for recreational use for adults aged 21 and over. With new patients and consumers entering the market every day, it’s more important than ever for cannabis cultivators to establish more effective methods for mold and fungal prevention in their crops and to ensure consumer confidence in their brands.

Today, many cultivators address the risk of mold and fungus growth by testing crops for contaminants at the end stage of production. While this helps to catch some infected product before it reaches the market, this method is largely ineffective for mold and fungal prevention during the cultivation process. In fact, recent studies have shown an 80% failure rate in mold and fungal testing in Denver cannabis dispensaries. By relying on late-stage, pass/fail testing, cannabis entrepreneurs also expose themselves to increased risk of lost crops and profits.

Photo credit: Steep Hill- a petri dish of mold growth from tested cannabis

However, emerging sensor technologies exist that can test plants during the grow process, significantly reducing the risks associated with cannabis cultivation while increasing the bottom line for commercial grow operations. By leveraging data from these monitoring sensors along with environmental automation systems that are integrated with data analytics platforms, cannabis professionals can take a proactive approach to achieve the ideal environmental conditions for their crops and prevent against mold and fungal infestation.

Common Causes for Bud Rot in Indoor Growing Systems 

Botrytis cinerea — commonly known as “bud rot” — is a pathogenic fungi species that creates a gray mold infection in cannabis plants. An air-borne contaminant, it is among the most prevalent diseases affecting marijuana crops today and can lead to significant damages, particularly when left untreated during post-harvest storage. Bud rot is one of the most difficult challenges cannabis entrepreneurs face: Once plants have been affected, only 2% can be expected to recover. This is because Botrytis cinerea can use multiple methods for attacking host plants, including using the plant’s natural defenses against it to continue infestation.

While difficult to contain, bud rot is very easy to spot. Plants affected with the fungus will begin yellowing, experience impaired growth, and develop gray fungus around its buds. Overall crop yield will be significantly reduced, leading to decreased profit for cannabis cultivators. The biggest contributing factors to a Botrytis cinerea infestation are as follows:

  • Humidity: Indoor grow facilities that maintain humidity levels in excess of 45% are breeding grounds for mold and fungus. These environments can become perfect conditions for mold and fungal growth.
  • Temperature: Bud rot typically thrives in environments where temperatures fall between 65- and 75-degrees Fahrenheit, which is why greenhouses and grow rooms are often the victim of such infestations.
  • Ventilation: Poor airflow is another contributing factor to Botrytis cinerea Without proper ventilation, excess moisture buildup will eventually result in mold and mildew growth.
  • Strain: Some marijuana strains are better equipped to fend off bud rot infection. In particular, sativa plants have a higher resistance to mold development than their C. indica and C. ruderalis cousins.

Controlling mold and fungal growth in commercial grow facilities is a top priority for cannabis cultivators. Not only detrimental to their profitability and crop yield, infected plants can pose serious health risks to consumers, especially for immunocompromised patients. Consuming cannabis products that have been compromised by bud rot or other mold and fungal infections can cause a wide range of medical concerns, including pneumonitis, bronchitis, and other pulmonary diseases. As a result, growers are required to dispose of all infected plants without the possibility to sell.

Bud rot isn’t the only culprit responsible for cannabis plant destruction. Powdery mildew, Fusarium, sooty molds, and Pythium all contribute to the challenges faced by cannabis professionals. In fact, a recent study conducted by Steep Hill Labs and University of California, Davis – Medical Center found that in 20 randomly-selected samples submitted for testing, all samples showed detectable levels of microbial contamination7. Many of these samples also contained significant pathogenic microorganism contamination. Without proper detection and prevention methods in place, these pesky plant-killers will only continue to terrorize the cannabis cultivation industry.

The Current Cannabis Cultivation Landscape 

The data is clear: Current practices for cannabis cultivation are insufficient for preventing against mold and fungal growth. Sterilization and pass/fail testing do not identify the root cause of harmful infestations in plants, therefore leaving cannabis professionals in the dark about how to better optimize their grow conditions for improved crop reliability and safety. In order to prevent against damages incurred from mold and fungal infestation, marijuana growers must be more diligent in their grow condition monitoring practices.

Many cannabis professionals rely on manual monitoring to identify environmental changes within their indoor grow facilities. While it’s important to collect data on your operation’s essential systems, doing so without the right tools can be time-consuming and ineffective. Manual monitoring often relies on past data and does not illustrate the relationship between different systems and their impact on environmental changes. The goal is to assemble data from all the grow systems and create correlations on actual bio-environmental conditions during the grow process to compare to yield results. This is only available when an information management platform is synthesizing data from all the systems within the grow facility and presenting meaningful information to the growers, facility operators and owners.

Especially as the cannabis industry is expected to grow exponentially in coming years, growers need more robust tools for tracking and manipulating environmental changes within their indoor growing systems.

Leveraging Building Automation Systems & Data Analytics in Cannabis Cultivation 

A powerful approach to prevent environmental conditions that are known to lead to mold and fungus growth exists in leveraging the data produced from your grow facility’s various automation systems. Most commercial cultivation facilities have multiple stand-alone and proprietary systems to control their indoor environment, making it difficult to not only collect all of this valuable data, but also to achieve the level of grow condition monitoring necessary for mold and fungal prevention.

With some data analytics platforms, such as GrowFit Analytics, data is collected across disparate systems that don’t normally communicate with one another, providing access to the key insights necessary for achieving environmental perfection with your cannabis crops. A viable solution collects vital grow facility system data and relevant bio-environmental monitoring data, and delivers this information in one, centralized software interface. The software then will apply analytic algorithms to develop key performance indicators (KPIs) while working to detect system anomalies, faults, and environmental fluctuations. The right analytics solution should also be customizable, allowing you to track the KPIs that are most important to your unique facility, and to achieve the vision of your chief grower. Ultimately, the software should serve up actionable insights that empower facility management and growers.

Sample data visualization dashboard from GrowFit Analytics showing real-time Temperature and Relative Humidity readings and indicating potential Mold Risk as defined by the Grower.

Collecting reliable data from different grow facility systems and environmental sensors can be a complex process and the information collected illustrates more than just what’s working right and what isn’t. By implementing an advanced data analytics solution, cannabis cultivation professionals can now be empowered to track minute details about their indoor grow facility, providing a safer, healthier environment for their crops and avoiding those environmental conditions that lead to mold and fungus altogether.

An ideal data analytics platform won’t simply collect data to be analyzed at a later date, and simple trending of sensor data is not enough. Information — especially in a commercial grow facility — is time-sensitive, which is why growers should select a system that offers real-time analytics capabilities. Some platforms offering real-time analytics utilize cloud computing, allowing for easy access from anywhere while also providing enhanced security to protect sensitive facility data. The most robust data analytics platforms provide detailed historical data for your entire crop’s lifecycle that provide a “digital recipe” to replicate successful crops, and fine-tune the process for continuous improvement.

Data analytics tools can also impact the bottom line by lowering operational costs. GrowFit Analytics, for example, was born out of a software solution designed to lower energy costs for large complex buildings like commercial grow facilities.

The data and insights provided can help identify opportunities for greater energy efficiency, which can lead to significant utility savings. Grow facilities operate 24 hours/day, with energy expenses representing one of the largest operational costs. With data analytics tools at their disposal, facility managers are armed with the information they need to improve system efficiency, increase energy savings, and improve profitability.

Eliminating Mold & Fungus from the Future of Cannabis Cultivation 

By focusing on grow condition monitoring using data analytics tools, cannabis professionals can effectively eliminate the risk of mold and fungus growth in their crops. Leading data analytics tools make tracking environmental changes simple and easy to manage, allowing cannabis professionals to take a proactive approach to mold and fungus prevention. As we look to the future of the cannabis cultivation industry, it’s paramount for professionals to explore the technological advancements available that can help them address their business’ most pressing challenges.

dry cannabis plants

How to Grow Cannabis Plants for Concentrate Production

By Andrew Myers
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dry cannabis plants

While flower is still the most popular way to consume cannabis, the concentrates market is booming. Some predict concentrates will be nearly as popular as flower by 2022, with an estimated $8.5 billion in retail sales. That’s a lot of concentrates and, chances are, cannabis producers are already feeling the pressure to keep up.

Concentrates refer to products made from processing cannabis – often resulting in much higher THC or CBD percentages. The category includes oils, wax, dabs, shatter, live resin and hash. Consumers are increasingly drawn to these cannabis products for their near-immediate and intense effects. They’re often consumed through vaporization, dabbing or sublingual absorption and are sometimes favored by those who want to avoid smoking. Cannabis growers who have traditionally focused on flower yields may decide to prioritize quality and potency levels in order to tap into these changing consumer tastes.

What Growers Should Focus on to Produce High Quality Concentrates
We’ll let you in on a little secret: making good concentrates starts with good flower. If you’re starting with low-quality flower, it’s impossible to create a high-quality concentrate. Whatever qualities inherent to the flower you’re starting with will be amplified post-processing. So, really, the concentrate-making process starts at the seedling level, requiring the right care and attention to coax out the results you’re looking for.

Tetrahydrocannabinol (THC), just one of hundreds of cannabinoids found in cannabis.

But what makes good flower? While this can be a subjective question, those producing concentrates generally look for flowers with big, abundant trichomes. Trichomes are the small, dewy structures found across the cannabis plant on buds, leaves and even the stem. They’re responsible for producing the plant’s cannabinoids and terpenes – the chemical compounds that give a strain its unique benefits, aroma and taste. Evolutionarily, trichomes attract pollinators, deter hungry herbivores and provide some defense against wind, cold and UV radiation.

Generally, trichomes indicate how potent the flower is. Plus, what we’re most often looking for when making concentrates is higher cannabinoid and terpene profiles, while also ensuring absolute safety.

What measures can growers take to produce crops that are ideal for concentrate production? Start with the following:

Avoiding Contaminants
Just like you would wash your fruits and vegetables before consumption, consumers want to be sure there’s no dangerous residuals in the concentrate they are ingesting. Growers can avoid any post-process residuals by taking a few key steps, including:

  • Photo: Michelle Tribe, Flickr

    Cutting out the pesticides. Any pesticides that are on your flowers before they go through processing will show up in your concentrates, often even more – you guessed it – concentrated. This is a serious health concern for consumers who might be sensitive to certain chemicals or have compromised immune systems. It’s dangerous to healthy consumers, too. Rather than spraying hazardous chemicals, growers could consider integrated pest management techniques, such as releasing predatory insects.

  • Limiting foliar spraying. Some growers will use foliar spraying to address nutrient deficiency or pest-related issues through delivering nutrients straight to the leaves. However, this can also result in contaminated concentrates. If you really need to spray, do it during the vegetative stage or investigate organic options.
  • Taking the time to flush the crop. This is a critical step in reducing potential contaminants in your concentrate, especially if you’re using a non-organic nutrient solution or fertilizer. Flushing simply means only giving your plants water during the final two weeks of flowering before harvest, resulting in a cleaner, non-contaminated flower and therefore a cleaner concentrate.

Perfecting the Indoor Environment
When cultivating cannabis indoors, growers are given ultimate control over their crop. They control how much light the plants receive, the lighting schedule, temperature and humidity levels. Creating the ideal environment for your cannabis crop is the number one way to ensure healthy plants and quality concentrates. There are many factors to consider when maintaining an indoor grow:

  • Temperature regulation. Trichomes are sensitive to temperature changes and start to degrade if they’re too hot or too cold. To maintain the best trichome structure, you’ll want to maintain an ideal temperature – for most strains, this falls between an idyllic 68 and 77 degrees.
  • Adequate light. For plants to perform photosynthesis indoors, they’ll need an appropriate light source – preferably one that is full-spectrum. Full-spectrum LEDs are able to closely replicate the sun and provide ample, uniform light to your crop. Another selling point for LEDs is their low heat output, making it much easier for growers to regulate ambient heat.

    dry cannabis plants
    Rows of cannabis plants drying and curing following harvest
  • CO2. Another necessary ingredient for photosynthesis is CO2. Providing your indoor crops with CO2 can boost plant size and yields and, therefore, provides more surface area for trichomes to develop and thrive.
  • Cold snap prior to harvest. Some growers rely on this age-old tactic for one last push before harvest – lowering their temperature for a few days right at the end of the flower cycle. They believe this puts the plants into a defense mode and will produce more trichomes in order to protect themselves.

Following Best Practices Post-Harvest
You made it to harvest – you’re almost done!

When harvesting and storing your plants, handle them with care to reduce damage to trichomes. If you’re planning on immediately making concentrates, you can move forward to the drying and curing process. If you’re going to wait a few weeks before processing, freeze your plants. This will preserve the cannabinoid and terpene profiles at their peak.

As the cannabis industry continues to expand, more consumers are likely to reach for concentrates at their local dispensaries. It makes sense that businesses want to diversify their offerings to satisfy customers looking for the most effective way to consume cannabis. As with any cannabis-derived product, producers will want to prioritize quality and safety – especially in the concentrate market.

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Increase Density in your Canopy

By Carl Silverberg
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One goal all growers seem to agree on is the need to increase density in their houses. How that gets done, well, there are a variety of ways and here’s one way a grower chose to do it:

With 45,000 square feet of greenhouse space, Nathan Fumia, a cannabis grower and consultant for a commercial operation in California, wasn’t pleased with what he was seeing. “If I put my hand inside the canopy and I can see sunlight on it, I’m losing money,” was how he described the situation. Unfortunately, the operators and staff of the greenhouse disagreed. They thought increasing density would rob the leaves of needed light.

He chose to test his theory by increasing the number of plants on one of his benches from 140 to 150 plants. To ensure the validity of the research, Nathan grew the same strain on Bench 1 as Bench 2, and to make sure all the metrics were equal, he even processed the crops separately. After weighing, Bench 2 (his research bench) showed an 8% higher yield than Bench 1.

“The post-harvest data from the weight, yield confirmed my decision to maximize density by increasing the total number of plants per bench,” says Fumia. “Whenever I saw red on the canopy heat map from LUNA, I knew there was room for improvement and I knew that I wasn’t making the money that I should have from those areas.”

His next challenge was where to place the extra ten plants? Did it make a difference or could he just shove 150 plants in a space that was originally planned for 140? Again, his greenhouse system was able to pinpoint the best sub-sections on the benches and Nathan was able to see exactly which plants were growing the fastest. That also gave him the ability to understand why certain quadrants of the bench were doing better than others.

“We were able to determine which quadrant on which bench was already at 100% density, and determine which quadrant wasn’t. Without that data, it would have been pure guesswork.”

He dialed down even further to find out which cultivars grew the best on a particular bench in the greenhouse. “Some cannabis cultivars need more light, some need less, some need warmer climates, and some need cooler climates,” Fumia noted. “Additionally, in order to increase the density of flowering points/buds, we began focusing on better pruning techniques in the vegetative phase, directly increasing branches for flowering.”

With optimization even more important now than it was 12-18 months ago, Nathan summed up the impact on his bottom line. “With a crop cycle averaging just over six a year, at that time we were averaging $600-$800 a pound depending on the strain. Some were even more. Ten extra plants per bench per cycle was a nice bounce for us.”

Obviously, this isn’t the only way to increase density. What’s your suggestion? Share your ideas with the rest of us by posting your comments below.

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Taking the Guesswork out of Horticultural Lighting

By Leora Radetsky
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With 33 states and the District of Columbia having passed laws legalizing marijuana in some form, cannabis cultivation is quickly becoming a booming new business across much of the US. From an energy standpoint, unfortunately, it’s not easy being “green”.

New Frontier Data’s 2018 Cannabis Energy Report found that legal cannabis cultivation in the US consumes approximately 1.1 million megawatt hours of electricity annually – enough to power 92,500 homes or a community the size of Newark, NJ, and accounts for carbon emissions equivalent to that of 92,600 cars. And that consumption is forecasted to increase 162 percent from 2017 to 2022. The report recommended that the industry “evaluate energy-efficient and renewable energy technologies” to nip this challenge in the bud.

Growers seeking to reduce their electricity usage through more efficient lighting face a confusing landscape of options, however. It can be difficult to know what will save electricity and work well for their operations. Technology is advancing quickly and questions abound, from how long a fixture will last and whether a manufacturer’s claims about efficacy are accurate to the effectiveness of various wavelengths for growing a particular plant.

Here’s the good news: there are reliable, third-party lighting and safety standards to help indoor growers make the leap from old-school lighting to state-of-the-art light-emitting diodes (LEDs) that use a fraction of the electricity and are increasingly effective for growing crops from cannabis to tomatoes. Here’s a closer look:

Most lighting fixtures in the North American market go through rigorous inspection by certified third-party testing labs. The first part of the check is for safety – an official UL safety standard tailored for the unique challenges of the greenhouse environment was recently released (UL 8800, the Standard for Horticultural Lighting Equipment and Systems). This standard and similar safety certifications at other major labs address wiring, environmental conditions, ingress protection and worker safety related to prolonged photobiological exposure to the eyes and skin. Growers should always ask a fixture manufacturer about safety certification specifically targeted for horticultural environments.

Next on the standards checklist for horticultural fixtures is performance testing. This often happens at the same labs that do safety testing, but is designed to verify efficacy, output, spectrum and other important performance variables. Commercial labs are certified for specific standards, so that a test on a fixture is repeatable at any other lab certified to the same standard. This performance testing results in a report summarizing items like photosynthetic photon flux (PPF), input power (watts), photosynthetic flux efficacy (PPE, measured in μmol/J or micromoles of photosynthetic photons per joule of electrical input power), and spectral content (flux per nanometer (nm) between 400 and 700 nm).

Then, there are flux maintenance standards (such as IES LM-80 and IES TM-21) that help make sure the photosynthetic light output of LED products degrades at an acceptable rate to make a grower’s investment worthwhile. The testing and calculation methods that go into these standards were painstakingly developed through a consensus of knowledgeable lighting stakeholders. A key difference between general lighting and plant lighting, however, is how flux maintenance is measured and benchmarked – the bar is significantly higher for plants compared to people since their metabolism and growth are dependent on the light spectrum and amount.

A plant in flowering under an LED fixture

What’s described above just scratches the surface of the detailed testing used to determine and communicate performance features for commercial horticultural lighting fixtures. There’s a lot of important information to know, but it takes an informed reader to analyze this information and use it to select appropriate horticultural lighting. Our organization, the DesignLights Consortium (DLC), strives to make the vetting process easier for everyone, freeing up growers to focus on their core business.

In the early days of LED lighting, electric utilities had to compare these different lighting factors and reports to inform their energy efficiency rebate/incentive programs. The DLC was founded to fill this need, serving as a central clearinghouse for setting energy efficiency and other product performance minimum standards, and to evaluate products against those standards. Then and now, lighting products that pass review qualify for an online qualified products list (QPL) that utilities use to quickly and accurately incentivize high-performing products.

Credit: ProGrowTech

With its new minimum performance standards for horticultural light fixtures, the DLC seeks to accelerate the adoption of new energy-saving LED fixtures in controlled agriculture environments. To be on the new DLC Horticultural QPL, an LED fixture must be at least 10 percent more efficacious than the best non-LED alternative – a 1,000-watt double-ended high-pressure sodium (HPS) fixture. It also must have a Q90 of 36,000 hours (the number of hours before the photon flux output depreciates to 90 percent), and its driver and fan (if included) must have a rated life of at least 50,000 hours.

Most importantly, every product is listed online in a searchable, filterable database to help growers and facility designers quickly narrow their options. For example, in a retrofit, a grower might know what PPF is needed from each fixture but might also need to stay within a power budget to avoid rewiring circuits. The DLC’s Horticultural QPL can be filtered to quickly find and compare conforming products.

When a new technology is introduced, there is always uncertainty about how to optimally apply it. The horticultural world is no different. We look forward to research supporting additional predictive metrics that allow us to take advantage of the full benefits of high-performance LED and controls technologies. In the meantime, the established standards described here allow for energy efficient and safe cultivation facilities where growers can confidently produce more with less.

dry cannabis plants

Moisture Matters: Why Humidity Can Make or Break a Cannabis Cultivator’s Bottom Line

By Sean Knutsen
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dry cannabis plants

Vintners have known for centuries that every step in the winemaking process—from cultivation and harvest techniques to fermentation, aging and bottling—has immense impact on the quality and value of the final product.

And that same level of scrutiny is now being applied to cannabis production.

As someone who has worked in the consumer-packaged goods (CPG) space for decades, I’ve been interested in finding out how post-harvest storage and packaging affect the quality and value of cannabis flower. After digging into the issue some more, storage conditions and humidity levels have indeed come into focus as major factors, beyond just the challenges of preventing mold.

Weighty Matters

I enlisted my research team at Boveda, which has studied moisture control in all manner of manufactured and natural CPG products, to look closer at what’s happening with cannabis once it leaves the cultivation room. There’s not a lot of research on cannabis storage—we checked—and so we explored this aspect further. We were frankly surprised by what a big effect evaporation has on quality and how this is playing out on the retail level.

We suspected moisture loss could affect the bottom line too, and so we did some number-crunching.

It’s well understood that the weight of cannabis flower directly correlates with its profitability—the heavier the yield, the higher the market value. Here’s what our analysis found: A mere 5% dip below the optimal relative humidity (RH) storage environment eliminates six pounds per every 1,000 pounds of cannabis flower. At $5 per gram wholesale, that works out to upwards of $13,500 in lost revenue—and that’s with just a 5% drop in RH below the target range of 55-65% established by ASTM International, an independent industry standards organization.

We also purchased flower at retailers in multiple state markets and commissioned a lab to test the samples, which revealed that most strains sold today are well below the optimal RH range (55-65%). Regardless of fluctuating wholesale prices, when you do the math it’s clear that tens of thousands of dollars in revenue are simply evaporating into thin air.

Why So Dry?

Historically, cultivators, processors and packagers have emphasized keeping flower below a particular humidity “ceiling” for a reason: Flower that’s too moist is prone to hazardous mold and microbial growth, so it’s understandable that many operators err on the side of being overly dry.

The misconception that cannabis flower can be “rehydrated” is another cause of dryness damage. But this method irrevocably damages the quality of the flower through trichome damage.

trichome close up
The fine outgrowths, referred to as trichomes, house the majority of the plant’s resin

Those delicate plant structures that house the all-important cannabinoids and terpenes become brittle and fragile when stored in an overly dry environment, and are prone to breaking off from the flower; they cannot not be recovered even if the flower is later rehydrated.

When trichomes are compromised, terpenes responsible for the aroma, taste and scent of cannabis also can evaporate. Overly dried-out cannabis doesn’t just lose weight and efficacy—it loses shelf appeal, which is particularly risky in today’s market.

Today’s consumers have an appreciation for how premium flower should look, smell and taste. Rehydration cannot put terpenes back in the flower, nor can it re-attach trichomes to the flower, which is why preservation of these elements is so key.

Cannabis Humidity Control

Cured cannabis flower can remain in storage potentially for months prior to sale or consumption. By the time it reaches the end consumer, much of the cannabis sold in regulated environments in the U.S. and Canada has suffered from dry damage.

dry cannabis plants
Rows of cannabis plants drying and curing following harvest

There are various humidity controls available for cannabis cultivators: desiccants that absorb water vapor; mechanical equipment that alters RH on a larger scale; or two-way humidity-control packets designed for storage containers.

In the CPG sector, with other moisture-sensitive products such as foods and electronics, we’ve seen that employing humidity controls will preserve quality, and cannabis flower is no different.

Saltwater-based humidity control solutions with two-way vapor-phase osmosis technology automatically add or remove water vapor as needed to maintain a constant, predetermined RH level and ensures a consistent level of moisture weight inside the cannabis flower.

Here’s one more notable finding we discovered in our storage research: Third-party lab tests commissioned by Boveda showed cannabis stored with humidity control had terpene and cannabinoid levels that were 15% higher than cannabis stored without.

Cannabis stored within the optimal humidity range maximizes all the qualities that attract and retain customers. Similar to wine-making, when cannabis cultivators focus on quality control they need to look beyond the harvest.

The Best Way to Remediate Moldy Cannabis is No Remediation at All

By Ingo Mueller
3 Comments

Consumers are largely unaware that most commercial cannabis grown today undergoes some form of decontamination to treat the industry’s growing problem of mold, yeast and other microbial pathogens. As more cannabis brands fail regulatory testing for contaminants, businesses are increasingly turning to radiation, ozone gas, hydrogen peroxide or other damaging remediation methods to ensure compliance and avoid product recalls. It has made cannabis cultivation and extraction more challenging and more expensive than ever, not to mention inflaming the industry’s ongoing supply problem.

The problem is only going to get worse as states like Nevada and California are beginning to implement more regulations including even tougher microbial contamination limits. The technological and economic burdens are becoming too much for some cultivators, driving some of them out of business. It’s also putting an even greater strain on them to meet product demand.

It’s critical that the industry establishes new product standards to reassure consumers that the cannabis products they buy are safe. But it is even more critical that the industry look beyond traditional agricultural remediation methods to solve the microbial problems.

Compounding Risks

Mold and other microbial pathogens are found everywhere in the environment, including the air, food and water that people consume. While there is no consensus yet on the health consequences of consuming these contaminants through cannabis, risks are certainly emerging. According to a 2015 study by the Cannabis Safety Institutei, molds are generally harmless in the environment, but some may present a health threat when inhaled, particularly to immunocompromised individuals. Mycotoxins resulting from molds such as Aspergillus can cause illnesses such as allergic bronchopulmonary aspergillosis. Even when killed with treatment, the dead pathogens could trigger allergies or asthma.

Photo credit: Steep Hill- a petri dish of mold growth from tested cannabis

There is an abundance of pathogens that can affect cannabis cultivation, but the most common types are Botrytis (bud rot, sometimes called gray mold) and Powdery Mildew. They are also among the most devastating blights to cannabis crops. Numerous chemical controls are available to help prevent or stem an outbreak, ranging from fungicides and horticultural oils to bicarbonates and biological controls. While these controls may save an otherwise doomed crop, they introduce their own potential health risks through the overexposure and consumption of chemical residues.

The issue is further compounded by the fact that the states in which cannabis is legal can’t agree on which microbial pathogens to test for, nor how to test. Colorado, for instance, requires only three pathogen tests (for salmonella, E. coli, and mycotoxins from mold), while Massachusetts has exceedingly strict testing regulations for clean products. Massachusetts-based testing lab, ProVerde Laboratories, reports that approximately 30% of the cannabis flowers it tests have some kind of mold or yeast contamination.

If a cannabis product fails required microbial testing and can’t be remedied in a compliant way, the grower will inevitably experience a severe – and potentially crippling – financial hit to a lost crop. Willow Industries, a microbial remediation company, says that cannabis microbial contamination is projected to be a $3 billion problem by 2020ii.

Remediation Falls Short
With the financial stakes so high, the cannabis industry has taken cues from the food industry and adopted a variety of ways to remediate cannabis harvests contaminated with pathogens. Ketch DeGabrielle of Qloris Consulting spent two years studying cannabis microbial remediation methods and summarized their pros and consiii.

He found that some common sterilization approaches like autoclaves, steam and dry heat are impractical for cannabis due the decarboxylation and harsh damage they inflict on the product. Some growers spray or immerse cannabis flowers in hydrogen peroxide, but the resulting moisture can actually cause more spores to germinate, while the chemical reduces the terpene content in the flowers.

Powdery mildew starts with white/grey spots seen on the upper leaves surface

The more favored, technologically advanced remediation approaches include ozone or similar gas treatment, which is relatively inexpensive and treats the entire plant. However, it’s difficult to gas products on a large scale, and gas results in terpene loss. Microwaves can kill pathogens effectively through cellular rupture, but can burn the product. Ionizing radiation kills microbial life by destroying their DNA, but the process can create carcinogenic chemical compounds and harmful free radicals. Radio frequency (which DeGabrielle considers the best method) effectively kills yeast and mold by oscillating the water in them, but it can result in moisture and terpene loss.

The bottom line: no remediation method is perfect. Prevention of microbial contamination is a better approach. But all three conventional approaches to cannabis cultivation – outdoors, greenhouses and indoor grow operations – make it extremely difficult to control contamination. Mold spores can easily gain a foothold both indoors and out through air, water, food and human contact, quickly spreading into an epidemic.

The industry needs to establish new quality standards for product purity and employ new growing practices to meet them. Advanced technologies can help create near perfect growing ecosystems and microclimates for growing cannabis free of mold contamination. Internet of Things sensors combined with AI-driven robotics and automation can dramatically reduce human intervention in the growing process, along with human-induced contamination. Natural sunlight supplemented with new lighting technologies that provide near full-light and UV spectrum can stimulate robust growth more resistant to disease. Computational fluid dynamic models can help growers achieve optimal temperature, humidity, velocity, filtration and sanitation of air flow. And tissue culture micropropagation of plant stock can eliminate virus and pathogen threats, to name just a few of the latest innovations.

Growing legal cannabis today is a risky business that can cost growers millions of dollars if pathogens contaminate a crop. Remediation methods to remove microbial contamination may work to varying degrees, but they introduce another set of problems that can impact consumer health and comprise product quality.


References

i. Holmes M, Vyas JM, Steinbach W, McPartland J. 2015. Microbiological Safety Testing of Cannabis. Cannabis Safety Institute. http://cannabissafetyinstitute.org/wp-content/uploads/2015/06/Microbiological-Safety-Testing-of-Cannabis.pdf

ii. Jill Ellsworth, June 2019, Eliminating Microbials in Marijuana, Willow Industries, https://willowindustries.com/eliminating-microbials-in-marijuana/#

iii. Ketch DeGabrielle, April 2018, Largest U.S. Cannabis Farm Shares Two Years of Mold Remediation Research, Analytical Cannabis, https://www.analyticalcannabis.com/articles/largest-us-cannabis-farm-shares-two-years-of-mold-remediation-research-299842

 

Alcaliber Spinoff Linneo Health Gets Greenhouse GMP Certification In Spain

By Marguerite Arnold
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As the industry faces what is undoubtedly a watershed moment for the international cannabis vertical, a new Spanish firm steps into the market with its own EU GMP certification license. Linneo Health is also helmed by the ever eloquent and highly experienced Jose Antonio de la Puente – a tall drink of water with a conscience, a brain and an admirable mission statement.

As Cannabis Industry Journal broke in our last story, a lack of international standards in Europe have been on trial of late. The same day that the CannTrust scandal began to blow in Canada and as Danish authorities rang global alerts, the only qualified packager in Holland was issued a new EU GMP cert. That is a government decision, not a commercial one.

This also implies, at minimum, government lack of coordination and agreement on EU GMP cert even between European nations, for a nascent industry while also trying to avoid the thorny issue of patient home grow. See also the trials and travails of the erstwhile German cultivation bid and its reconstituted Frankenstein-esque bigger if younger sister. In fact, this contretemps is almost certainly involved if not indirectly to blame.

Not All Is Entirely Rosy On Cannabis Europe’s Eastern Front

Almost simultaneously to Linneo Health’s announcement, however, the news came that in Poland, authorities had suspended the pending product registration process. Will this be on hold until after the October election?

In this environment it is almost impossible to know.

Here is one thing to consider. These almost simultaneous developments in Spain and Poland and the newest announcement about further certification of the Dutch recreational system under a new pending “recreational trial” are almost directly related.

That said, even such political maneuverings are not new – and far from limited to any single company. Both Germany and Poland have been wracked by reform stuttered by short term gain and market entry strategies executed by most of the biggest players in the room. Aurora, for example, announced their first import into Poland the same day the Polish government changed the law last fall. Aurora uses Germany as its breakpoint distribution center for Europe.

A Stamp of Authenticity That Is Sorely Needed

Beyond the pharma and market entry politics, however, this Alcaliber-helmed project creates a ring of authority to the same that creates at least one cannabis brand the European medical community can see the certification for.

For now at least, certainly among the ranks of the upper echelons of the international cannabis industry, there must surely be a sigh of relief.

EU GMP certifications (in other words, the authorization to produce product bound for a medical, pharma market) do not happen overnight. On the European front, this is surely at least a step in the right direction for an industry embattled by scandals, particularly of the securities, production, certification and accounting kind right now.

In this case, however, it is also clear that no matter the egregious oversteps and potentially illegal and certainly dubious behaviour of some members of the industry, there are also clearly those within it, and at high levels, who have tried to do the right thing. And further, from the beginning of the nascent industry here as of 2015.

Who Is Alcaliber?

Alcaliber is one of the world’s largest opioid manufacturers. Unlike American counterparts, the company decided several years ago to invest in and back ideas of the opioid-to-cannabinoid therapy model. Linneo Health is a 60% subsidiary of Alcaliber and 40% owned by a Spanish family office called Torreal, S.A.

This is, as a result, one of the most important GMP licenses in Europe at the moment if not the world. It means that within a pharmaceutical environment, the first widespread research and production of plants and therapies for those suffering from both chronic pain, plus neurological and oncological conditions that cause or are related to the same, will be put on a fast track long in the offing. Certainly in Europe.

And that for one, is a positive development that will have widespread implications elsewhere. Particularly given the news that the opioid epidemic in the United States finally has a name, and culpable parties.

What Else Is Unusual About This Project?

GMP certification is a vastly misunderstood concept at the moment. It is also a highly thorny one because of a still standardizing set of agreements. The regulatory environment is in place, in other words, but there are many, many gaps, as well as shifting rules and underlying treaties.

GMPHowever, on top of this, there is also an amazing lack of innovation in interpretation, in part because of many misadvised consultants who are actually seeking to “save” production costs for their clients, or because they do not know any better. Or because producers are scared of doing the wrong thing.

The new project in Spain is unusual because it is a greenhouse grow that got EU GMP cert – although look for more of this in the future. It means that with careful, standardized, pharma production, not all regulated cannabis grows, even for the medical market, have to use huge amounts of energy in repurposed post-industrial developments. It is also certainly cleaner than growing outside. And, when done right, saves huge amounts of water.

Cleantech, in other words, has finally hit the cannabis industry in Europe. As well as a pharmaceutical company invested in the cannabinoid treatment of (at least) chronic pain.

That is an overdue and hugely positive development. No matter what else can be said for shenanigans engulfing the rest of the industry at the moment.

Soapbox

The Stress of a Grower

By Carl Silverberg
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Tell me that you can’t relate to this story.

You’re sitting down to dinner at a restaurant about ten minutes from where you work, finally relaxing after a tough day. You’ve set your environmental alerts on your plants; you have that peace of mind that the technology promised and you know that if anything goes wrong you’ll get notified immediately. As you’re looking at the menu, you receive an alert telling you that the temperature in one of your 2,000 square foot grow rooms has gone out of the safe range. Your mind starts to race, “It’s week seven, I’ve got 500 plants one week away from harvest, that’s 200 pounds of cannabis worth about $150,000-$200,000. Oh my God, what am I going to do?”

You’re doing all this at the dinner table and even though you’re not in a state of panic, you are extremely concerned. You need to figure out what’s going on. You check the graphing and see that over the past hour your humidity dropped and your temperature is gradually going up. Within the past ten minutes, the temperature has gone to 90 degrees. Your numbers tell you that the temperature in the room with $200,000 of cannabis is going up about five degrees every three minutes.

adamJgrow
Monitoring a large grow room can be a stressful task.

“I see this trend and can’t figure it out,” the grower relates. “Normally, the HVAC kicks on and I’d begin to see a downward trend on the graphs. I pre-set my trigger for 90 degrees. But, I’m not seeing that. What I AM seeing is the temperature gradually and consistently getting warmer without the bounce-back that I would expect once the HVAC trigger was hit. All I know is I better find out what’s causing all this and I better find out fast or my entire crop is gone.”

You go through the rest of the checklist from LUNA and you see that the lights are still on. Now, you’re starting to sweat because if the temperature in that room hits 130 and stays there for more than twenty minutes, you’re losing your entire crop. You have to walk in your boss’s office the next day and explain why, after all the time and money you put in over the past seven weeks, not only is all that money gone but so is the $200,000 he is counting on to pay salaries, expenses, and bank loans.

This is something you’ve been working on for seven straight weeks and if you don’t make the right decision, really quickly, when that room hits 130 degrees here’s what happens.

“My equipment starts to fail,” our grower continues. “The crop literally burns as the oils dry up and the crop is worthless. At 130 degrees, my grow lights essentially start to melt. All you can think of is that temperature going up five degrees every three minutes and you’re ten minutes from your facility. I need to leave that restaurant right now, immediately, because even if I get there in ten minutes the temperature is going to be almost 120 degrees while I’ve been sitting here trying to figure out what’s wrong.”

You run out to your car and you speed back to the facility. The grow room is now 125 degrees, you have maybe three or four minutes left to figure things out before you flush $200,000 down the drain. The first thing you do is turn off the grow lights because that’s your primary source of heat. Then, you check your HVAC panel and you realize it malfunctioned and shorted out. There’s the problem.

The real toll is the human cost. Once this happens, no grower ever wants to leave and go home or even go to dinner. It’s a horrible toll. It’s the hidden cost we don’t talk about. The grower opens up with his own personal experience.“This system allows the grower to step back and still feel confident because you’re not leaving your facility to another person,” 

“You think about the burden on the person that you bring in to replace you while you’re out of town and then you think about the burden on you if something goes wrong again. And you decide, it’s not worth it. The anxiety, the fear that it will happen again, it’s not worth it. So, you don’t go. I didn’t even see my sister’s new baby for eight months.”

Your desire to see your family, your desire to have a normal life; all of that goes out the window because of your desire to be successful in your job. It outweighs everything.

This is every grower. It’s why many farmers never leave their property. It just becomes a normal way of living. You just repeat it so much that you don’t even think about it. Why go on vacation if your stress level is higher than it is if you’re home. You’re constantly worried about your farm or your facility. The only way to escape it is to not go away at all.

“This system allows the grower to step back and still feel confident because you’re not leaving your facility to another person,” he tells us. “You don’t realize how stressful a lifestyle you live is until you step back and look at it. Or, if you have an alert system that allows you to pull back. That’s when you realize how difficult your life is. Otherwise, it just seems normal.”

As AI technology expands its footprint into agriculture, there will be more tools to help mediate situations like this; more tools to give you a more normal life. It’s one of the reasons we got into the business in the first place.

Fungal Monitoring: An Upstream Approach to Testing Requirements

By Bernie Lorenz, PhD
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Mold is ubiquitous in nature and can be found everywhere.1 Cannabis growers know this all too well – the cannabis plant, by nature, is an extremely mold-susceptible crop, and growers battle it constantly.

Of course, managing mold doesn’t mean eradicating mold entirely – that’s impossible. Instead, cultivation professionals must work to minimize the amount of mold to the point where plants can thrive, and finished products are safe for consumption.

Let’s begin with that end in mind – a healthy plant, grown, cured and packaged for sale. In a growing number of states, there’s a hurdle to clear before the product can be sold to consumers – state-mandated testing.

So how do you ensure that the product clears the testing process within guidelines for mold? And what tools can be employed in biological warfare?

Mold: At Home in Cannabis Plants

It helps to first understand how the cannabis plant becomes an optimal environment.

The cannabis flower was designed to capture pollen floating in the air or brought by a pollinating insect.

Photo credit: Steep Hill- a petri dish of mold growth from tested cannabis

Once a mold spore has landed in a flower, the spore will begin to grow. The flower will continue to grow as well, and eventually, encapsulate the mold. Once the mold is growing in the middle of the flower, there is no way to get rid of it without damaging the flower.

A Name with Many Varieties

The types of spores found in or around a plant can make or break whether mold will end with bad product.

Aspergillus for example, is a mold that can produce mycotoxins, which are toxic to humans2. For this reason, California has mandatory testing3for certain aspergillus molds.

Another example, Basidiospores, are found outside, in the air. These are spores released from mushrooms and have no adverse effects on cannabis or a cannabis cultivation facility.

Fungi like powdery mildew and botrytis (PM and Bud Rot) typically release spores in the air before they are physically noticed on plants. Mold spores like these can survive from one harvest to the next – they can be suspended in the air for hours and be viable for years.

How Mold Travels

Different types of spores – the reproductive parts of mold – get released from different types of mold. Similar to plants and animals, mold reproduces when resources are deemed sufficient.

The opposite is also true that if the mold is under enough stress, such as a depleting nutrient source, it can be forced into reproduction to save itself.4

In the end, mold spores are released naturally into the air for many reasons, including physical manipulation of a plant, which, of course, is an unavoidable task in a cultivation facility.5

Trimming Areas: A Grow’s Highest Risk for Mold

Because of the almost-constant physical manipulation of plants that happen inside its walls, a grow’s trimming areas typically have the highest spore counts. Even the cleanest of plants will release spores during trimming.

Best practices include quality control protocols while trimming

These rooms also have the highest risk for cross contamination, since frequently, growers dry flower in the same room as they trim. Plus, because trimming can be labor intensive, with a large number of people entering and leaving the space regularly, spores are brought in and pushed out and into another space.

The Battle Against Mold

The prevalence and ubiquitous nature of mold in a cannabis facility means that the fight against it must be smart, and it must be thorough.

By incorporating an upstream approach to facility biosecurity, cultivators can protect themselves against testing failures and profit losses.

Biosecurity must be all encompassing, including everything from standard operating procedures and proper environmental controls, to fresh air exchange and surface sanitation/disinfection.

One of the most effective tactics in an upstream biosecurity effort is fungal monitoring.

Ways to Monitor Mold

Determining the load or amount of mold that is in a facility is and always will be common practice. This occurs in a few ways.

Post-harvest testing is in place to ensure the safety of consumers, but during the growing process, is typically done using “scouting reports.” A scouting report is a human report: when personnel physically inspect all or a portion of the crop. A human report, unfortunately, can lead to human error, and this often doesn’t give a robust view of the facility mold picture.

Another tool is agar plates. These petri dishes can be opened and set in areas suspected to have mold. Air moves past the plate and the mold spores that are viable land on the dishes. However, this process is time intensive, and still doesn’t give a complete picture.

Alternatively, growers can use spore traps to monitor for mold.

Spore traps draw a known volume of air through a cassette.The inside of the cassette is designed to force the air toward a sticky surface, which is capable of capturing spores and other materials. The cassette is sent to a laboratory for analysis, where they will physically count and identify what was captured using a microscope.

Spore trap results can show the entire picture of a facility’s mold concerns. This tool is also fast, able to be read on your own or sent to a third party for quick and unbiased review. The information yielded is a useful indicator for mold load and which types are prevalent in the facility.

Spore Trap Results: A Story Told

What’s going on inside of a facility has a direct correlation to what’s happening outside, since facility air comes infromthe outside. Thus, spore traps are most effective when you compare a trap inside with one set outside.

When comparing the two, you can see what the plants are doing, view propagating mold, and understand which of the spore types are only found inside.

Similar to its use in homes and businesses for human health purposes, monitoring can indicate the location of mold growth in a particular area within a facility.

These counts can be used to determine the efficacy of cleaning and disinfecting a space, or to find water leaks or areas that are consistently wet (mold will grow quickly and produce spores in these areas).

Using Spore Traps to See Seasonality Changes, Learn CCPs

Utilizing spore traps for regular, facility-wide mold monitoring is advantageous for many reasons.

One example: Traps can help determine critical control points (CCP) for mold.

What does this look like? If the spore count is two times higher than usual, mitigating action needs to take place. Integrated Pest Management (IPM) strategies like cleaning and disinfecting the space, or spraying a fungicide, are needed to bring the spore count down to its baseline.

For example, most facilities will see a spike in spore counts during the times of initial flower production/formation (weeks two to three of the flower cycle).

Seasonal trends can be determined, as well, since summer heat and rain will increase the mold load while winter cold may minimize it.

Using Fungal Monitoring in an IPM Strategy

Fungal monitoring – especially using a spore trap – is a critical upstream step in a successful IPM strategy. But it’s not the only step. In fact, there are five:

  • Identify/Monitor… Using a spore trap.
  • Evaluate…Spore trap results will indicate if an action is needed. Elevated spore counts will be the action threshold, but it can also depend on the type of spores found.
  • Prevention…Avoiding mold on plants using quality disinfection protocols as often as possible.
  • Action…What will be done to remedy the presence of mold? Examples include adding disinfection protocols, applying a fungicide, increasing air exchanges, and adding a HEPA filter.
  • Monitor…Constant monitoring is key. More eyes monitoring is better, and will help find Critical Control Points.

Each step must be followed to succeed in the battle against mold.

Of course, in the battle, there may be losses. If you experience a failed mandatory product testing result, use the data from the failure to fix your facility and improve for the future.

The data can be used to determine efficacy of standard operating procedures, action thresholds, and other appropriate actions. Plus, you can add a spore trap analysis for pre- and post- disinfection protocols, showing whether the space was really cleaned and disinfected after application. This will also tell you whether your products are working.

Leveraging all of the tools available will ensure a safe, clean cannabis product for consumers.


References

  1. ASTM D8219-2019: Standard Guide for Cleaning and Disinfection at a Cannabis Cultivation Center (B. Lorenz): http://www.astm.org/cgi-bin/resolver.cgi?D8219-19
  2. Mycotoxin, Aspergillus: https://www.who.int/news-room/fact-sheets/detail/mycotoxins
  3. State of California Cannabis Regulations: https://cannabis.ca.gov/cannabis-regulations/
  4. Asexual Sporulation in Aspergillus nidulans (Thomas H. Adams,* Jenny K. Wieser, and Jae-Hyuk Yu):  https://pdfs.semanticscholar.org/7eb1/05e73d77ef251f44a2ae91d0595e85c3445e.pdf?_ga=2.38699363.1960083875.1568395121-721294556.1562683339
  5. ASTM standard “Assessment of fungal growth in buildings” Miller, J. D., et al., “Air Sampling Results in Relation to Extent of Fungal Colonization of Building Materials in Some Water Damaged Buildings,” Indoor Air, Vol 10, 2000, pp. 146–151.
  6. Zefon Air O Cell Cassettes: https://www.zefon.com/iaq-sampling-cassettes