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

In this episode of the Cannabis Cultivation and Science Podcast, host Tad Hussey welcomes back Julie Graesch, Technical Services Manager at Bioworks, to dive deep into the science and practical application of oil-based products in cannabis cultivation. The conversation explores the critical differences between horticultural mineral oils and essential oil-based 25B products, emphasizing their modes of action—including suffocation, desiccation, and behavioral disruption—and why these physical mechanisms make resistance development far less likely than with chemical pesticides. Julie stresses the dangers of using kitchen oils like olive or canola oil, explaining that DIY formulations lack proper emulsifiers, spreading agents, and precise formulations, increasing the risk of phytotoxicity and inconsistent results. She also clarifies the regulatory landscape, distinguishing between EPA-registered products and FIFRA 25B biopesticides, and underscores the importance of evaluating product data, formulation quality, concentration, and label claims. The discussion highlights key factors in product selection, including emulsification, surfactant use for better coverage, tank mixing compatibility with microbes like Beauveria bassiana, and the strategic use of both oil types to target different pest life stages—especially eggs—while minimizing plant stress and maximizing efficacy. A major takeaway is the importance of using formulated, label-compliant products over homemade alternatives, with Julie advocating for a dual-strategy approach: using horticultural mineral oils (like SUF oil) for broad-spectrum control including egg stages and essential oil-based 25B products (like EpiShield) for zero REI and targeted knockdown. The episode concludes with practical advice on dipping for new plant material, rotating treatments to prevent buildup, and leveraging resources like Bioworks’ tank mix compatibility guides and Julie’s article 'Oils: Myths and Magic' from Greenhouse Product News. Listeners are encouraged to identify pests accurately, test new products in their own operations, and prioritize safety and science over marketing hype.