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To quarantine a cannabis plant means to place it in isolation in a separate location because it is assumed that plant potentially has been exposed to contagious diseases or pests.

In multiple articles over the years, I’ve mentioned the need to quarantine new genetics, clones and various inputs before introducing them to the cultivation environment. But what does it really mean to quarantine a cannabis plant? How can you ensure plants are properly isolated until they are ready to be introduced into the growing environment?

As it turns out, it’s not that different from what humans have been doing for the better part of 16 months.

To quarantine a cannabis plant means to place it in isolation in a separate location because that plant potentially has been exposed to contagious diseases or pests. All new genetics, even if plants are from trusted and reliable sources and suppliers, should be quarantined before introducing them into a grow environment. 

Designate a Space

Quarantining agricultural products and some plants or plant material is a standard practice in commercial agriculture that is enforced by the U.S. Department of Agriculture. Whether the products are imported fruits and vegetables or fresh cut flowers, all are inspected either before export or after import, and sometimes both. In some instances, goods or products must be quarantined prior to distribution.

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In a perfect world, a cannabis cultivation facility would have a designated quarantine facility off-site, nowhere near the cultivation environment. At this separate location, clones, plants and seedlings could be thoroughly inspected and tested to make absolutely sure the plant is pest- and disease-free.

But few of us live in a perfect world and can afford a standalone quarantine facility. Therefore, a designated quarantine environment can be built within the cultivation facility as far away from other plants as possible. A highly trained employee should also be responsible for the quarantine area, where they exclusively work and avoid walking past or through other cultivation areas. 

Get the Right Equipment 

The quarantine area should be a completely sealed environment and employees should have access to:

  • a separate entrance whenever possible, not shared with other environments;
  • a negative-pressure environment so that any pest or disease proliferation is minimized;
  • separate ventilation ducting with air sterilizing capabilities for both incoming air as well as exhausted air to prevent cross-contamination via ventilation from another environment;
  • designated employee clothing and footwear (e.g. Tyvek suits and hairnets);
  • a decontamination booth/blow-off booth (BOB) that uses powerful jets of air to remove potential contamination particles from employees’ clothing, shoes and hair;
  • foot washing/sterilization mats at the door.

Additionally, protocols should be in place to prevent employee cross-contamination, including, but not limited to, preventing departments (such as the propagation team or the flowering team) from interacting.

The Quarantine Process

A typical quarantine lasts for four weeks, depending on how thorough and proactive the technicians are in their observation, inspection and testing. Quarantine periods should be at least four weeks to ensure any symptoms manifest themselves before the plants are moved into the main facility.

While the plants are in quarantine:

1. Visually inspect all aspects of the plant and monitor regularly.
    Look in the crevices of all new vegetation, and look at all the undersides of leaves to search for pests, eggs or feces from pests such as spider mites and aphids. Visually inspect plants for signs of powdery mildew or other undesirable aspects, such as symptoms or signs of Hop Latent Viroid (HpLVd), which include curled leaves, yellow streaks and other anomalies. Also, consider using a magnifying device during inspections to get a closer view of small pests.
2. Conduct a photo inspection.
    Growers should photograph and log all aspects of the plant, including the topsand bottoms of all leaves. The photos then can be inspected further on a computer by zooming in on questionable areas. Pests such as broad mites or russet mites that may not be visible to the naked eye become visible on a monitor.
3. Use video, too.
    Just like photo inspections, video recordings also can and should be used to track progression and be available to reference later should a problem arise.
4. Constantly and thoroughly inspect all media.
    Visually inspect growing media for pests such as fungus gnats and or fungus gnat larvae. Whenever possible, utilize a microscope to inspect the media for pests or root disease such as pythium or root rot. Take both photos and videos of the growing media so they can be reviewed at a later time.
5. Preventively test for viral infections.
    While the plants are quarantined, consider performing tests for viral infection. There are multiple test kits for HpLVd, as well as tobacco mosaic virus test strips and Sunn-hemp mosaic virus detection kits. Unfortunately, there are very few scientific test kits available to test cannabis diseases, and these are some of the very few that exist. As of now, researchers are not positive how many viruses cannabis and/or hemp plants are susceptible to and which ones growers should test.
6. Clean and sanitize the space between quarantines.
    Disinfection and sterilization whenever possible also are paramount. After each quarantine cycle, the quarantine environment must be disinfected utilizing hydrogen peroxide and UV light sterilizers (the UV treatment ensures all surfaces that come into contact with the light are disinfected, while the peroxide can get into table undersides and areas that the light can’t reach). All related materials must also be disinfected or sterilized between cycles, if not more often.

Anytime new genetics are destined to be incorporated into your grow, they must always be properly and thoroughly quarantined, regardless of whether you’re cloning your plants yourself, buying clones from another nursery, purchasing tissue cultures or starting from seed. Skipping this vital step can be detrimental to your crop. Isolating new, potentially infected seedlings and/or clones is the best way to ensure that you’re not accidentally bringing a potentially devastating pest or disease into your grow.

Kenneth Morrow is an author, consultant and owner of Trichome Technologies. Facebook: Trichome Technologies Instagram: Trichome Technologies k.trichometechnologies@gmail.com