Emerging diseases of Cannabis sativa and sustainable management

Abstract

Cultivation of cannabis plants (Cannabis sativa L., marijuana) has taken place worldwide for centuries. In Canada, legalization of cannabis in October 2018 for the medicinal and recreational markets has spurned interest in large‐scale growing. This increased production has seen a rise in the incidence and severity of plant pathogens, causing a range of previously unreported diseases. The objective of this review is to highlight the important diseases currently affecting the cannabis and hemp industries in North America and to discuss various mitigation strategies. Progress in molecular diagnostics for pathogen identification and determining inoculum sources and methods of pathogen spread have provided useful insights. Sustainable disease management approaches include establishing clean planting stock, modifying environmental conditions to reduce pathogen development, implementing sanitation measures, and applying fungal and bacterial biological control agents. Fungicides are not currently registered for use and hence there are no published data on their efficacy. The greatest challenge remains in reducing microbial loads (colony‐forming units) on harvested inflorescences (buds). Contaminating microbes may be introduced during the cultivation and postharvest phases, or constitute resident endophytes. Failure to achieve a minimum threshold of microbes deemed to be safe for utilization of cannabis products can arise from conventional and organic cultivation methods, or following applications of beneficial biocontrol agents. The current regulatory process for approval of cannabis products presents a challenge to producers utilizing biological control agents for disease management. © 2021 The Author. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genome-Wide Characterization of the MLO Gene Family in Cannabis sativa Reveals Two Genes as Strong Candidates for Powdery Mildew Susceptibility

“…Fungicides are widely used to prevent and control this disease in agricultural settings. However, a scarce amount of such products are currently approved by Health Canada as the presence of fungicide residues in the inflorescences raises concerns ( Punja, 2021 ). Besides, they are costly, and fungicide resistance in PM has been observed and documented in other plant species in recent years ( Vielba-Fernández et al, 2020 ).…”

“…Besides, they are costly, and fungicide resistance in PM has been observed and documented in other plant species in recent years ( Vielba-Fernández et al, 2020 ). Alternative approaches to managing this disease have been described, such as the use of biological control (e.g., Bacillus subtilis strain QST 713), reduced risk products (e.g., potassium bicarbonate, knotweed extract), and physical methods (e.g., de-leafing, irradiation) ( Punja, 2021 ). Nonetheless, some of these methods increase production costs, are labor-intensive, and necessitate further research.…”

Root-TRAPR: a modular plant growth device to visualize root development and monitor growth parameters, as applied to an elicitor response of Cannabis sativa

“…These infections suppress plant growth, reduce yield and product quality in both outdoor elds and greenhouse settings [21]. However, the pathology underlying the different infections is currently poorly understood and disease management programs have not been fully established [22]. The growers may apply inorganic agents, for example potassium bicarbonate, hydrogen peroxide, boric acid, orthosilicic acid or synthetic fungicides such as uopyram to moderate or eradicate fungal pathogens [23].…”

Genome-wide characterization of the MLO gene family in Cannabis sativa reveals two genes as strong candidates for powdery mildew susceptibility

“…The copyright holder for this preprint (which this version posted July 16, 2021. ; https://doi.org/10.1101/2021.07.16.452661 doi: bioRxiv preprint risk products (e.g., potassium bicarbonate, knotweed extract), and physical methods (e.g., deleafing, irradiation) (Punja, 2021). Nonetheless, some of these methods increase production costs, are labor-intensive, and necessitate further research.…”

“…Besides, they are costly, and fungicide resistance in PM has been observed and documented in other plant species in recent years (Vielba-Fernández et al, 2020). Alternative approaches to managing this disease have been described, such as the use of biological control (e.g., Bacillus subtilis strain QST 713), reduced risk products (e.g., potassium bicarbonate, knotweed extract), and physical methods (e.g., deleafing, irradiation) (Punja, 2021). Nonetheless, some of these methods increase production costs, are labor-intensive, and necessitate further research.…”