Episode 162: Dips, Sprays, & Phytotoxicity: Mastering Oils in Cannabis Cultivation with Julie Graesch

Cannabis Cultivation and Science Podcast

Tad Hussey.

Grow, Leisure, Natural Sciences, Cannabis, Science, Cultivation, Gardening, Weed, Organics, Home & Garden, Growing, Marijuana

4.7 • 716 Ratings

🗓️ 7 April 2026

⏱️ 56 minutes

🔗️ Recording | iTunes | RSS

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Summary

In this episode, Tad Hussey welcomes back Julie Graesch, Technical Services Manager at BioWorks, to demystify one of the most common yet misunderstood tools in a grower’s IPM toolkit: Horticultural and Essential Oils. While many growers reach for oils to "suffocate" pests, the science behind their efficacy—and the risks of phytotoxicity—is far more complex. Julie breaks down the critical differences between EPA-registered mineral oils and 25B essential oil products, explaining how different modes of action like desiccation, paralysis, and behavioral repellency work together to bypass pest resistance. They also dive into the "why" behind professional formulations, discussing how emulsifiers and surfactants make the difference between a clean kill and a scorched crop.

Transcript

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0:00.0	Welcome to the Cannabis
0:03.0	Welcome to the Cannabis Cultivation and Science Podcast.
0:23.1	I'm your host, Tad Hussey of Kiss Organics.
0:27.7	This is the podcast where we discuss the cutting edge of growing from a science-based perspective and drawn top experts from around the industry to share their wisdom and knowledge.
0:32.0	Just a friendly reminder to folks who enjoy the podcast content and want to support the podcast,
0:36.7	we have a Patreon where we do a book club,
0:38.9	hangouts, and share private content that I don't share on social media. With Patreon, you also get
0:43.8	access to a private Discord channel and I upload the raw podcast interviews immediately. Sometimes
0:48.8	it can be weeks prior to the public release. We also offer a wide range of products ranging from
0:54.0	living soils,
0:54.8	beneficial insects, organic fertilizers, and professional consulting on our Kiss Organics website.
1:01.7	Now my guest this week is a returning guest. Julie Gresh works for Bioworks as a technical
1:06.6	services manager. Julie has 18 years of experience as a biological scientist, practiced in
1:12.1	laboratory, greenhouse, and field research, as well as technical service support for the
1:16.4	integrated pest management industry. She has been with Bioworks for over five years and had
1:21.1	previously held positions at BASF, Becker Underwood, and Iowa State University. Now on to the
1:27.2	show.
1:45.3	Hey, Julie, welcome back to the show. Thanks, Tad. It's great to be here. Yeah, I'm so glad we got to connect again. And I'm really excited today to learn all about oils. And I thought we could start off this conversation with just a really simple question, which is why would I want to use an oil? And then the follow up to that is like, why can't I just go
1:51.7	use canola oil or olive oil out of my kitchen? What are those differences and what are the oils
1:58.2	really doing for my plants? Great questions. So why would you use
2:05.2	an oil over something else? Oils, whether that is a horticultural mineral oil or a essential
2:12.3	oil product, have the mode of action is, there's multiple modes of action. But the main mode of action with, say, a horticultural mineral oil is suffocation. And when we're talking about these physical modes of action, we are also talking about or can talk about things like resistance. And if you're
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