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This video features Kristin Nevedal, Director of American’s For Safe Access Patient Focused Certification Program, who gives insight on pesticide use in cannabis cultivation. She explains the current landscape of pesticides regulation, pest management, and the need for further research. Thank you to Care By Design for helping to sponsor this video series.


Project CBD: Today we’re talking to Kristin Nevedal, the director of Americans for Safe Access Patient Focused Certification program. Kristin is one of the co-founders of the Emerald Growers Association, now known as the California Growers Association. And also, I want to get this exactly right, you’re the chairperson of the American Herbal Products Association Cannabis Committee’s Cultivation Working group.

Kristin Nevedal: That is correct.

Project CBDFor cannabis cultivators pest management is a crucial issue. We’ve had reports out of Colorado recently, and other states, grappling with the fact that they’re finding high residue levels of pesticides in the plant matter from the cannabis growers. How extensive a problem is this actually?

Nevedal: You know, I think it’s kind of hard to gauge how extensive of a problem it is, and I think really the issue is a lack of education on this topic, frankly. So, currently all pesticides in the United States are subject to tolerance thresholds, which is what determines the appropriate spray ratios. And so, what I mean by that is: Can the pesticide be used on an ornamental crop only or is it approved for use on a crop that’s produced for human consumption? And at what rates can you use it on a crop produced for human consumption? This is why we see on pesticide labels different spray protocols for say strawberries versus a squash or an ear of corn. But that has not been established for cannabis. So what we currently have are cannabis farmers who are utilizing pesticides based on how they work on other crops or successes that they might be hearing or reading about on forums. And really, the only legal pesticide products out there are those that are deemed so safe by the Environmental Protection Agency that they don’t require a tolerance to be set. They’re part of the tolerance exempt list.

Project CBDSo when you say “tolerance exempt,” what do you actually mean? And who sets the standards, who regulates pesticides? Is this a federal issue? Is this a state issue?

Nevedal: It’s a little bit of both. The Environmental Protection Agency sets pesticide standards and tolerances nationally, right. And then each state has the ability to take that list or those – say, an intolerance exempt product, the EPA will create a federal list and then each state has the ability to, say, narrow that list down. It can’t make broader exemptions to what the EPA regulates. So, in California the Department of Pesticide Regulations has reviewed the Environmental Protection Agency’s tolerance exempt list, and they’ve taken a couple of products off of it, such as sulfur. So, federally the EPA would consider that a tolerance exempt product. However, the Department of Pesticide Regulation in California doesn’t see it the same way. They see it as having more risk than what the Environmental Protection Agency sees.

Project CBDHas there been, then, standards set for cannabis cultivators by the state of California? I know they’re trying to do this in Oregon and Washington, Colorado as well.

Nevedal: Yeah, I mean there aren’t currently. What the Department of Pesticide Regulation in California has determined or stated is that only the products that qualify as tolerance exempt products should be appropriate for use on cannabis. So, anything not – it’s interesting because on labels we have signal words, right, and they’re arranged in five different categories. So, when a cannabis product doesn’t have a signal word on it, then we know it’s tolerance exempt. Signal words are, something that might say ‘warning’ or ‘caution’ or ‘danger.’ But in tolerance exempt products, there’s no signal word on it, which is supposed to tell the user that that product is safe for all crops produced for human consumption. And that the spray periods in that crop’s life cycle don’t need to be considered necessarily. So those are the products that cultivators should be sticking with, are those tolerance exempt products.

Project CBDSo a product like Eagle 20 or Avid, which I know that sometimes cannabis growers are utilizing at different phases of the grow cycle, is this – these should be avoided.

Nevedal: Always. Always. So these are pretty toxic pesticide products. In California, both Eagle 20 and Avid, are restricted pesticide products, so they do require a applicators license in order to legally obtain and utilize commercially. So, they are – they’re illegal. No matter how you slice it or look at it, both of those products are illegal for use on cannabis. And that’s true in all states.

Project CBDSo, if a pesticide is considered tolerance exempt does that mean that a farmer, it’s okay for that person to utilize that product at any point in the plant’s life cycle?

Nevedal: That’s a tricky one, because there’s so much that we don’t know, because none of these experiments have been done with cannabis. But, let’s take a product like Bacillus Subtilis, for example, which is what we see in Serenade, which is an over-the-counter tolerance exempt product. Because cannabis, once it starts to produce flowers, the pesticide product will kind of hide in between the stem and that new flower production, and it’s a bacteria-based pesticide product – it’s alive, that’s how it works, it eats up the mildew spores, that’s what the bacteria does. So if you’re spraying that product late, once the flowers are developing and you don’t have sunlight coming into contact with that product, that live bacteria is allowed to proliferate and then you’re likely going to fail a microbiological exam.

Project CBDSo ordinarily the sunlight would break down this type of pesticide. And do the pesticides ever become systemic, not just simply stay on the leaf or whatever, that they actually get in the plant itself so that if one extracts oil, for example, essential oil of the cannabis plant, are you also extracting the pesticide?

Nevedal: It depends on the pesticide product. So tolerance exempt pesticides don’t tend to be systemic. They tend to work on the surface of the plant. But, if you have that residue on the surface of the plant, there is – it’s likely that you could concentrate it through an extraction process. And again, some of that is unknown without having these experiments from the EPA. There’s just a lot that we don’t know.

The very best time to handle the risk associated with disease and pest on this crop is going to be early on in the vegetative state of the plant’s life. And the goal here is to never have the disease show up. So it you’re not acting preventatively, and I don’t mean just with pesticides, I mean preventatively as far as how are you treating your soil, is your soil alive, is it full of microbes, is it full of beneficial bacteria, what kind of precautions are you taking with your clothing, are you walking into a contaminated site and then walking through your garden? Are, you’re bringing that disease with you on your clothes, on your shoes? So, we really as cultivators need to be very mindful about how to not bring the disease home – and then, how to use very safe products and treatments to make sure that we’re preventing its onset. The entire reason why we have disease outbreaks is because, as cultivators, we’ve created a very friendly environment for that disease. So we have to mind our environmental controls, we have to mind all points of contamination, whether that’s soil, plant matter we’re bringing in, clothing, compost. So it’s really about the preventative components. That’s what’s going to result in success.

Project CBDAnd that would underscore the importance of this integrated pest management concept, which entails more than just simply the pesticides one would use, whether they’re natural or safer, to deal with bugs or whatever is going on with the plants.

Nevedal: Right. I mean, if we’re in an environment outdoors or in a greenhouse, what kinds of plants are around our ventilation, around our garden, and even focusing on planting plants such as lavender, yarrows, that are going to bring in beneficials will really help to balance our environment. You know, one of my favorite things has been to, say, release praying mantises. They are vicious little buggers and they eat all sorts of pests, and they will stay in your garden and feast year after year after year.

Project CBD: In essence, you’re kind of augmenting what the plants already do, because plants release terpenes that will attract certain kinds of animals or insects that will then attack their predators or that will repel predators and so forth. So you’re basically working with the essence or the energy of the plant and augmenting what it needs.

Nevedal: Absolutely – and finding that environmental balance. You know, if we’re say in a row cover and we notice that we have some spider mites starting, just take the cover off that row cover and you’re going to see these beneficials come in, eat up your spider mites, and not ever have to treat. It can really be that simple. But it takes a very watchful eye. And you have to really garden year-round; think about what kinds of pests. Like right now is a great time to be spraying beneficial Nematodes.

Project CBD: “Now” being, we’re talking, middle of the winter in Northern California.

Nevedal: Yes, absolutely, because cucumber beetles are going to hatch out as soon as it starts to get warm, right, thrips are larvaeing in the soil right now. So if we are mindful and we’re thinking about issues maybe we experienced last year, we can – over the course of the winter when we’re dormant – we can treat for those issues with beneficials. So, it’s really kind of changing the way you look at pesticides and making a plan to act very preventatively.

Project CBD: Thank you Kristin Nevedal. That’s good advice. I appreciate you joining us today on Cannabis Conversations.

Nevedal: Thank you so much for having me.

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