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Fusarium Species Infecting Greenhouse-Grown Cannabis (Cannabis sativa) Plants Show Potential for Mycotoxin Production in Inoculated Inflorescences and from Natural Inoculum Sources

Summary

Researchers found that certain fungi called Fusarium species can infect cannabis flowers growing in greenhouses and produce harmful toxins called mycotoxins. These toxins, which can accumulate in dried cannabis buds, come from both direct infection and from nearby tall fescue grass plants growing outside the greenhouse. The study shows that high humidity conditions in greenhouses can promote fungal growth and toxin production, potentially affecting cannabis safety. Different cannabis varieties showed varying levels of toxin accumulation despite similar fungal infection rates.

Background

Several Fusarium species are reported to infect cannabis inflorescences in Canadian greenhouses, causing bud rot symptoms. The primary concern is potential mycotoxin accumulation that may go undetected in cannabis tissues destined for medicinal and recreational use. Previous studies have documented Fusarium infections on cannabis but not the associated mycotoxin production.

Objective

To confirm Fusarium species present on infected cannabis inflorescences and determine mycotoxin content using HPLC-MS/MS analysis. To conduct artificial inoculation studies demonstrating pathogenicity and mycotoxin production. To investigate potential external sources of Fusarium inoculum infecting greenhouse cannabis.

Results

F. graminearum produced 3-acetyl DON, DON, and zearalenone at levels of 0.13-0.40, 1.18-1.91, and 31.8-56.2 μg/g respectively. F. sporotrichiodes produced HT2 and T2 toxins at 13.9 and 10.9 μg/g. F. avenaceum produced enniatins A, A1, B, and B1 at varying concentrations. Tall fescue plants near the greenhouse harbored both F. avenaceum and F. graminearum, suggesting external inoculum sources.

Conclusion

Infection by F. graminearum and F. avenaceum from both artificial inoculation and natural inoculum sources can lead to mycotoxin accumulation in cannabis inflorescences under high humidity conditions. Tall fescue and other grasses adjacent to greenhouses represent potential reservoirs of Fusarium inoculum. Development of management strategies including buffer zones and cultivar selection may reduce mycotoxin contamination risk.
  • Published in:Journal of Fungi,
  • Study Type:Experimental Study,
  • Source: 10.3390/jof11070528, PMID: 40985446
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