OBJECTIVE

To evaluate the phytotoxicity risk of a novel biopesticide product applied by dipping four Cannabis sativa cultivars.

CHALLENGE

Plant Products Inc. (Plant Products) delivers focused technical support and consumable goods to the specialty horticulture industries in Canada and the USA. They’re a leading distributor of fertilizers, synthetic and biological pesticides, biological control, substrates, seeds, and other innovative products.

The mantra in Integrated Pest Management (IPM) is to start clean. This includes good sanitation practices and starting crops from cuttings that are free of pests. However, this is a challenge for cutting producers worldwide due to increasing pesticide resistance and difficulties in targeting all life stages, and insects/mites on stock plants. Consequently, many cuttings arrive from offshore facilities carrying significant numbers of pests. When this happens, every tool in the IPM arsenal (including chemicals) often don’t stand a chance, and crop and revenue losses are inevitable.

Over the past 10 years, Canadian researchers have tested both the phytotoxicity and efficacy, of dipping incoming plant cutting material (fully submerge for 30 seconds). The dipping technique proved to be more efficacious at killing pests on incoming cuttings than foliar sprays and allows ornamental grower to start clean. However, there is always a risk that the product, or its concentration can cause irreversible phytotoxicity. Thus, every crop, and each cultivar, need to be tested separately. To date, no such studies have been performed in commercial cannabis, which sadly often experiences crop failure due to early infestation of hitchhikers arriving to new facilities on incoming cutting materials.

Plant Products’ novel biopesticide product could have higher mortality against target pests, while having less or no phytotoxicity in cannabis plants. Taking examples from the ornamental industry, dipping incoming cannabis cuttings in such a product could kill the pests without having any negative impact on the plants, which would drastically improve pest management in the cannabis industry overall.

SOLUTION

Using robust scientific protocol, Plant Products and the Horticultural and Environmental Sciences Innovation Centre (HESIC) combined their efforts to evaluate the phytotoxicity risks of this novel product, at various concentrations, to cannabis plant cuttings as a dip. Our results showed that the novel product did cause mild phytotoxicity at all concentrations tested, especially the two highest concentrations of 0.7 and 1.0 ml/L. Phytotoxicity presented mostly as leaf tip burn and yellowing leaves and was more pronounced for ‘Karel’s Haze’ and ‘Whiteshark’ cultivars. The product negatively impacted powdery mildew infestation as well. For future work, we suggest more trials with more repetitions at lower than 0.2 ml/L product concentrations.

This novel biopesticide was registered in the US in fall 2023 under the name EpiShield™ by BioWorks.