Early Pathogen Detection
With DNA-based pathogen detection assays from Medicinal Genomics, cannabis and hemp cultivators can identify plants infected with a number of molds, mites, viruses, and viroids, including powdery mildew, botrytis, russet mites, fusarium, hops latent viroid, and lettuce chlorosis virus. Cultivators who use this preventive strategy can reduce their risk of suffering costly pathogen outbreaks and improve yield.
Hop Latent Viroid
Hop latent viroid (HLVd) is a single-stranded, circular infectious RNA that completely depends on the metabolism of the host plant. As the name suggests, HLVd was first identified in the hop plant, but it can also infect cannabis, which is a relative of hops. In fact, some experts claim the effects of the disease are even more serious in cannabis, causing stunted plants with small, loose buds that have fewer trichomes. Once infected, plants can only be saved via a lengthy tissue culture process that will produce a new viroid-free plant.
Lettuce Chlorosis Virus
Lettuce chlorosis virus (LCV) is a linear, single-stranded positive-sense RNA virus and a member of the Crinivirus family. Cannabis and hemp plants that are infected early will suffer stunted growth, but may not show visual signs until a few weeks into flowering. Those visual signs of LCV infection include yellow, rolling, brittle leaves. While the infection does not kill cannabis and hemp plants, it significantly affects yield and potency. The plant will produce smaller flowers with fewer trichomes, cannabinoids, and terpenes.
Cannabis Cryptic Virus
Cannabis cryptic virus (CCV) is a double-stranded RNA virus and a member of the Partitiviridae family. Researchers detected CCV in leaves showing signs of hemp streak virus; however, the presence of CCV alone did not cause streak symptoms. It’s possible that CCV interacts with other fungal pathogens to produce disease symptoms in cannabis and hemp plants, which is why monitoring the presence of CCV could be valuable. Furthermore, CCV can be vertically transmitted through seeds, which means breeders may want to screen plants before crossing.
Tobacco Mosaic Virus
Tobacco Mosaic Virus (TMV) is a positive-sense single-stranded RNA virus that infects a number of different plants, most notably tobacco. Although there are no documented cases of TMV infecting cannabis or hemp plants in the literature, many growers suspect TMV in plants that develop a mosaic-like pattern of discoloration on the leaves that cannot be attributed to nutrient deficiencies. Our team has screened several suspected TMV plants only to find Hop Latent Viroid. While this does not rule out the possibility of TMV infecting cannabis and hemp plants, we have not been able to confirm an infection, yet.
Powdery Mildew
Powdery Mildew is arguable the most destructive Cannabis pest. It is an obligate biotroph that can vascularize into the plant tissue and remain invisible to a grower. It tends to emerge and sporulate 2 weeks into flowering thus destroying very mature crop with severe economic consequences. It is believed to travel in clones and its is not known if it travels in seeds. Other stressful events like cloning can trigger Powdery Mildew spore formation.
Botrytis
Botrytis cinerea is a systemic mold infection in Cannabis. This mold is often called “Bud Rot” or “grey mold”. It can remain cryptic or dormant for long periods of time before it sporulates. The infection starts within the bud, making it difficult to detect in the early stages of infection. Peer-reviewed papers have also demonstrated that Botrytis is a systemic infection that can be passed to future generations via seeds.
Russet Mites
The microscopic Hemp Russet mite infects cannabis and can result in significant crop loss and chronic infestations. Russet mites are 200um x 45um and are thus invisible to the eye until late infection when their numbers begin to discolor the plant.
Russet mites are resistant to most pest treatments and thus care must be taken to screen incoming material to a grow. Visual detection of mature mites is possible with 14X objective loupe but eggs and nymphs likely escape convenient optical detection. They are believed to be hosts for other plant viruses.
Fusarium
Fusarium is a soil-dwelling fungus that causes yellowing and wilting of cannabis leaves and stems. The fungus can sit dormant in soil for years before becoming active and infecting a viable host plant. There is no effective treatment against fusarium. Cannabis plants that are infected are a lost cause, as well as any seeds they produce.
Two Options for Pathogen Detection
Use the youPCR® Plant Screening Platform to test 4mm biopsy of the plant leaf. If the sample contains DNA of the target pathogen, a chemical reaction will turn the pink solution yellow, indicating a positive result.
Use the PathoSEEK® Microbial Safety Testing Platform to test 4mm biopsy of the plant leaf. If the sample contants DNA of the target organism, the assay will emit a fluorophore signal that the qPCR instrument will display on a computer screen.
Prefer to Outsource Testing?
Cultivators who don’t have enough volume, lab experience, or start-up cash to test plants in-house can outsource to one of our partner labs. Fill out the form below and we will connect you with one in your area, if available.
Available Pathogen Detection Products
| Item # | Name | Reactions | |
|---|---|---|---|
| 420507 | PathoSEEK® Cannabis Virus Multiplex Assay A Starter Bundle | 200 | Buy Now |
| 420121 | PathoSEEK® Cannabis Virus Multiplex Assay A (HLVd, LCV, and Cannabis Cryptic Virus) | 200 | Buy Now |
| 420123 | PathoSEEK® Hop Latent Viroid Positive Control | 60 | Buy Now |
| 420124 | PathoSEEK® Cannabis Cryptic Virus Positive Control | 60 | Buy Now |
| 420125 | PathoSEEK® Lettuce Chlorosis Virus Positive Control | 60 | Buy Now |
| 420128 | PathoSEEK® Tobacco Mosaic Virus Detection Assay | 200 | Buy Now |
| 420132 | PathoSEEK® Tobacco Mosaic Virus Positive Control | 50 | Buy Now |
| 420115 | PathoSEEK® Powdery Mildew Detection Assay | 200 | Buy Now |
| 420216 | Powdery Mildew Positive Control | 50 | Buy Now |
| 420211 | youPCR® Solution B – Powdery Mildew | 50 | Buy Now |
| 420222 | Botrytis Positive Control | 50 | Buy Now |
| 420221 | youPCR® Solution B – Botrytis | 50 | Buy Now |
| 420224 | Russet Mites Positive Control | 50 | Buy Now |
| 420223 | youPCR® Solution B – Russet Mites | 50 | Buy Now |
| 420146 | PathoSEEK® Russet Mite Detection Assay | 200 | Buy Now |
| 420219 | youPCR® Solution B – Fusarium oxysporum | 50 | Buy Now |
| 420220 | Fusarium oxysporum Control | 50 | Buy Now |
| 420117 | PathoSEEK® Fusarium oxysporum Detection Assay | 200 | Buy Now |
Still have questions? Don’t hesitate to reach out to us.
Frequently Asked Questions
No. Although we have done some initial research into using youPCR® to test seeds, we have not done enough to confidently say it works as well as testing leaf. We recommend sampling a seedling’s first set of true leaves when using youPCR®.
youPCR® assays provide a positive/negative result. When using youPCR® to screen for CBDA or THCA synthase, a positive result means there is an active CBDA or THCA synthase allele. Unfortunately, that result can’t be used to predict what percentage the plant will ultimately produce. However, if you combine the CBDA and THCA tests you can determine the plant type.
- Type I Plant (THCA-dominant) = THCA(+) CBDA(-)
- Type II Plant (THCA:CBDA hybrid) = THCA(+) CBDA (+)
- Type III Plant (CBDA-dominant) = THCA(-) CBDA(+)
- Type IV Plant (CBGA-dominant) = THCA(-) CBDA(-)
No. Plants that test negative for THCA or CBDA may still produce low percentages (<2%) of either compound.
No. Cannabis plants typically hermie as a response to stress. Although there may be genetic markers that determine if a plant is more likely to hermie, we have not found them, and we do not target them with our gender test. The youPCR® Gender Assay specifically looks for a Y chromosome.
The youPCR® Starter Kits do not include PCR Thermal Cyclers. We recommend the following models:
- miniPCR. Use Promo Code “MGC” to receive a discount off list price.
The youPCR® Starter Kits also do not include chemical reagents: Solution A, Solution B, Solution C, and Positive Control. Those must be purchased separately on the Medicinal Genomics web store.
In order to successfully test with youPCR®, you should have experience with the following laboratory techniques/best practices:
- Liquid handling with a pipette
- Benchtop sterility techniques
- Proper disposal of tips, punches, strip tubes
All of the chemicals and reagents we sell in our webstore are manufactured in facilities that are certified to ISO 9001 and/or ISO 13485 standards.