Harvest and Post-Harvest

Caplan, Deron; Matzneller, Philipp; Gutierrez, Juan David

doi:10.1201/9781003150442-10

Cited by 4 publications

(12 citation statements)

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“…The overall increase in TYM levels can cause a product to fail to pass regulatory limits set by specific jurisdictions and cause the product to be rejected for sale. inflorescence leaves after drying (Caplan et al, 2022). In a previous study (Punja et al, 2019), wet trim was reported to cause injury to inflorescence leaves that resulted in a significant build-up of microbial populations post-harvest.…”

Section: Discussionmentioning

confidence: 94%

“…Pichia and Candida species were recovered at a much lower frequency from cannabis inflorescences in this study and their potential importance remains undetermined. Commercial drying of cannabis inflorescences is performed in specially designed drying rooms over a 5-7 day period at 21-23°C and 40-55% relative humidity (Caplan et al, 2022). These conditions ensure a slow removal of moisture to a final content of 12-14%, equating to a water activity of 0.65-0.7 (Caplan et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

“…Commercial drying of cannabis inflorescences is performed in specially designed drying rooms over a 5-7 day period at 21-23°C and 40-55% relative humidity (Caplan et al, 2022). These conditions ensure a slow removal of moisture to a final content of 12-14%, equating to a water activity of 0.65-0.7 (Caplan et al, 2022). Two general methods for handling cannabis inflorescences post-harvest are: (i) rack (screen) drying, where individual buds are mechanically removed from the stem followed by mechanical trimming of the inflorescence leaves (wet trim) and then dried, and (ii) hang-dry, where entire stems are hung upside down with leaves attached followed by trimming the A summary of the potential variables and factors which can cause a build-up of total yeasts and molds in cannabis inflorescences, many of which were confirmed in this study.…”

Section: Discussionmentioning

confidence: 99%

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Total yeast and mold levels in high THC-containing cannabis (Cannabis sativa L.) inflorescences are influenced by genotype, environment, and pre-and post-harvest handling practices

Punja,

Ni,

Lung

et al. 2023

Front. Microbiol.

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Total yeast and mold (TYM) levels in inflorescences of high THC-containing Cannabis sativa (cannabis) are regulated to ensure that medicinal and recreational users, especially those with immunocompromised systems, are not exposed to potentially harmful levels. In North America, the limits imposed range from 1,000–10,000 cfu/g of dried product to 50,000–100,000 cfu/g, depending on the jurisdiction. Factors affecting a build-up of TYM in cannabis inflorescences have not been previously researched. In this study, >2,000 fresh and dried samples were assayed for TYM over a 3-year period (2019–2022) to identify specific factors which can contribute to TYM levels. Greenhouse-grown inflorescences were sampled before and after commercial harvest, homogenized for 30 s, and plated onto potato dextrose agar (PDA) with 140 mg/L streptomycin sulfate. Colony-forming-units (cfu) were rated after 5 days of incubation at 23°C under 10–14 h light. PDA provided more consistent counts of cfu compared to Sabouraud dextrose and tryptic soy agars. The predominant fungal genera identified by PCR of the ITS1-5.8S-ITS2 region of rDNA were Penicillium, Aspergillus, Cladosporium, and Fusarium. In addition, four yeast genera were recovered. In total, 21 species of fungi and yeasts constituted the total cfu present in the inflorescences. The variables that significantly (p < 0.05) increased these TYM levels in inflorescences were: the genotype (strain) grown, presence of leaf litter in the greenhouse, harvesting activity by workers, genotypes with a higher abundance of stigmatic tissues and inflorescence leaves, higher temperature and relative humidity within the inflorescence microclimate, time of year (May–October), method of drying buds after harvest, and inadequate drying of buds. The variables which significantly (p < 0.05) decreased TYM in samples were: genotypes with lower numbers of inflorescence leaves, air circulation achieved by fans during inflorescence maturation, harvesting during November–April, hang-drying of entire inflorescence stems, and drying to a moisture content of 12–14% (water activity of 0.65–0.7) or lower which was inversely correlated with cfu levels. Under these conditions, the majority of dried commercial cannabis samples contained <1,000–5,000 cfu/g. Our findings indicate that TYM in cannabis inflorescences are the result of a dynamic interaction between genotype, environment, and post-harvest handling methods. Some of these factors may be altered by cannabis producers to reduce the potential build-up of these microbes. Among the 21 fungal and yeast species recovered from greenhouse-grown cannabis inflorescences, a few could pose a potential threat to human health, while many do not and they could provide beneficial interactions within the cannabis plant. The currently recommended plating methods onto agar media and enumeration of total cfu are unable to distinguish between these two groups.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Total yeast and mold levels in high THC-containing cannabis (Cannabis sativa L.) inflorescences are influenced by genotype, environment, and pre-and post-harvest handling practices

Punja,

Ni,

Lung

et al. 2023

Front. Microbiol.

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“…Following the harvest of cannabis inflorescences, they undergo a phase of drying to reduce the moisture content to levels that would minimize the development of microbes [ 19 , 20 , 52 ], following which they are trimmed and prepared for packaging and stored prior to shipment. During each of the post-harvest processing stages, there is the potential for microbial contamination to be increased, primarily consisting of total yeasts and molds (TYM), total aerobic microbial count (TAMC), and bile-tolerant Gram-negative count (BTGN).…”

Section: Cannabis Pathogens: Symptoms and Management Approaches At Di...mentioning

confidence: 99%

“…Detailed studies are lacking regarding at which specific stages the levels of microbes may build-up to cause the final product to potentially fail to meet regulatory standards. However, pre-harvest, it has been shown that cannabis genotype and growing conditions can significantly influence TYM build-up; in addition, post-harvest drying methods and handling practices can affect TYM levels [ 19 , 20 , 52 ]. A number of commonly encountered fungi have been identified on dried cannabis products pre- and post-harvest ( Figure 15 ), and they contribute to TYM levels [ 19 ].…”

Section: Cannabis Pathogens: Symptoms and Management Approaches At Di...mentioning

confidence: 99%

Integrated Management of Pathogens and Microbes in Cannabis sativa L. (Cannabis) under Greenhouse Conditions

Buirs,

Punja

2024

Plants

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The increased cultivation of high THC-containing Cannabis sativa L. (cannabis), particularly in greenhouses, has resulted in a greater incidence of diseases and molds that can negatively affect the growth and quality of the crop. Among them, the most important diseases are root rots (Fusarium and Pythium spp.), bud rot (Botrytis cinerea), powdery mildew (Golovinomyces ambrosiae), cannabis stunt disease (caused by hop latent viroid), and a range of microbes that reduce post-harvest quality. An integrated management approach to reduce the impact of these diseases/microbes requires combining different approaches that target the reproduction, spread, and survival of the associated pathogens, many of which can occur on the same plant simultaneously. These approaches will be discussed in the context of developing an integrated plan to manage the important pathogens of greenhouse-grown cannabis at different stages of plant development. These stages include the maintenance of stock plants, propagation through cuttings, vegetative growth of plants, and flowering. The cultivation of cannabis genotypes with tolerance or resistance to various pathogens is a very important approach, as well as the maintenance of pathogen-free stock plants. When combined with cultural approaches (sanitation, management of irrigation, and monitoring for diseases) and environmental approaches (greenhouse climate modification), a significant reduction in pathogen development and spread can be achieved. The use of preventive applications of microbial biological control agents and reduced-risk biorational products can also reduce disease development at all stages of production in jurisdictions where they are registered for use. The combined use of promising strategies for integrated disease management in cannabis plants during greenhouse production will be reviewed. Future areas for research are identified.

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Integrated Management of Pathogens and Microbes on <em>Cannabis sativa</em> L. (Cannabis) under Greenhouse Conditions

Buirs,

PUNJA

2024

Preprint

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The increased cultivation of high THC-containing Cannabis sativa L. (cannabis), particularly in greenhouses, has resulted in a greater incidence of diseases and molds that can negatively affect the growth and quality of the crop. Among them, the most important diseases are root rots (Fusarium and Pythium spp.), Botrytis bud rot (Botrytis cinerea), powdery mildew (Golovinomyces ambrosiae), cannabis stunt disease (caused by Hop latent viroid), and a range of microbes that reduce post-harvest quality. An integrated management approach to reduce the impact of these diseases/microbes requires combining different approaches that target the reproduction, spread and survival of the associated pathogens, many of which can occur on the same plant simultaneously. These approaches will be discussed in the context of developing an integrated plan to manage the important pathogens of greenhouse-grown cannabis at different stages of plant development. These stages include maintenance of stock plants, propagation through cuttings, vegetative growth of plants, and flowering. The cultivation of cannabis genotypes with tolerance or resistance to various pathogens is a very important approach, followed by the maintenance of pathogen-free stock plants. When combined with cultural approaches (sanitation, management of irrigation, and monitoring for diseases) and environmental approaches (greenhouse climate modification), a significant reduction in pathogen development and spread can be achieved. The use of preventive applications of microbial biological control agents and reduced risk biorational products can also reduce disease development at all stages of production in jurisdictions where they are registered for use. The combined use of promising strategies for integrated disease management on cannabis plants during greenhouse production will be reviewed. Future areas for research are identified.

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Harvest and Post-Harvest

Cited by 4 publications

References 0 publications

Total yeast and mold levels in high THC-containing cannabis (Cannabis sativa L.) inflorescences are influenced by genotype, environment, and pre-and post-harvest handling practices

Total yeast and mold levels in high THC-containing cannabis (Cannabis sativa L.) inflorescences are influenced by genotype, environment, and pre-and post-harvest handling practices

Integrated Management of Pathogens and Microbes in Cannabis sativa L. (Cannabis) under Greenhouse Conditions

Integrated Management of Pathogens and Microbes on <em>Cannabis sativa</em> L. (Cannabis) under Greenhouse Conditions

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