Small pest, big problem: innovative strategies to manage hemp russet mite in hemp

Cannabis sativa, or hemp, is quickly becoming a crop of global agricultural importance, yet pests associated with the crop and pest management needs are essentially undescribed. Among the most serious hemp pests is a microscopic mite, Aculops cannabicola, the Hemp Russet Mite (HRM). Due in part to its minute size, HRM can go unrecognized by growers and the extent of its economic impact is likely underestimated. This is compounded by the difficulty to eradicate this pest, particularly in indoor cultivation where it can proliferate across crop cycles. The current study is the first report of the life cycle of the HRM. We evaluated HRM populations in field plants treated with a variety of biological controls, and chemical controls compared to untreated plants. Our results showed varying levels of efficacy in reducing HRM population levels on treated plants. Experiments are underway to assess the impact of HRM on phytocannabinoids and yield. In a laboratory setting, we demonstrate that hot water immersion can eradicate HRM without causing phytotoxicity to hemp cuttings. Outcomes of this research will provide hemp producers and other stakeholders key pest management tools needed to produce hemp plants that are free of HRM.