Assessment of four biological control agents on the suppression of Fusarium proliferatum on vegetative cannabis plants in a soilless system

The advancement of Cannabis sativa production for medical and recreational use has led to new reports of various pathogens and diseases that are challenging to control with current management practices. High quality, medicinal cannabis is typically grown indoors for its uniformity and consistent properties. Currently, there are very limited-registered pesticides for use on cannabis in Canada to protect these high value crops from pathogens. Additionally, high use of pesticides can have adverse effects on human health and the environment, making alternatives to chemical pesticides highly sought after. Biological control agents provide an alternative to pesticide use. However, there has been minimal work dedicated to evaluate the ability of beneficial microorganisms to suppress endophytic pathogens such as Fusarium on cannabis plants. The objective of this research was to assess whether biological control agents containing different microbial species can reduce the incidence and severity of Fusarium proliferatum on infected Cannabis plants grown in a soilless cultivation system. Two cultivars of Cannabis sativa, ‘Duke Nukem’ and ‘Royal Goddess’, were used in this trial. Transplants were dipped in one of four biocontrol agents (Rootshield WP, Jumpstart WP, Actinovate AG and Quickroots) before being inoculated with a liquid spore suspension of F. proliferatum. Control plants received either no biological control agents and no pathogen, or no biological control but with Fusarium inoculation only. No positive plant growth promotion was observed in this trial, while Actinovate AG and Rootshield WP significantly reduced the disease spread up to 35 and 49 days post inoculation. This study provides efficacy results of biological control agents on controlling F. proliferatum in a soilless system.