Tag Archives: powdery

Building An Integrated Pest Management Plan – Part 5

By Phil Gibson
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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?

Figure 2: Thrip Evidence c/o UC ANR Publication 7429

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.

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

By Ingo Mueller
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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