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The Benefits of Bio-control for Growing Cannabis Plants

By Amanda Brown
Published: August 1, 2016 | Last updated: May 11, 2021
Key Takeaways

​When it comes to pest control and your cannabis crop, it pays to arm yourself with good bugs before the bad bugs take over. Crop protection specialist Amanda Brown provides an anecdote and helpful insight on how to ensure the good bugs win and why bio-control is beneficial.

I walked into the room looking pretty cool with my sunglasses over my glasses, decked out in a Tyvek suit four times too big, and braced for the worst. What I saw was even worse than that. A sea of spider mite webbing covered the entire crop, flowers and all. The entire facility was infested and sprays that had long ago stopped being effective were being applied every two days. Needless to say, this was not the best time to start a bio-control program, but the growers were left with no other option. So we began strategizing. It’s the quintessential Good Bug vs. Bad Bug conflict, and we had to be sure that good would prevail.

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Bio-Control Tips for Cannabis Plants

Bio-control for cannabis makes perfect sense. It reduces the time required for spraying and exposure to employees, it eliminates the need for chemicals on a medicinal crop, it’s affordable and it works. A bio-control program involves releasing beneficial organisms that will feed on or kill the pests threatening your crop. With a preventative approach, growers know that the good bugs are in their crop working hard before anyone, even an experienced scout, has spotted a pest yet.

(Read also: Lock Up the Biosecurity of Your Grow Op)

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Bio-Control Agents for Cannabis Plants

Bio-control agents can be predatory mites, parasitic wasps, or entomopathogenic nematodes, just to name a few. They are your warriors, and it is always wise to build your army before the pests build theirs. Some bio-control agents can feed on other food sources, and so can be released with this alternate food before any pests are present in the crop. Other bio-control agents are so specific that they will only feed on spider mites, for example. In this case, we sometimes release them preventatively, knowing that they will die if they don’t find food, but that they will save you from headaches later if they do find their food source.

Spider Mites Bio-Control

You’re wondering what happened to that spider mite infestation, aren’t you? The webbed crop was vacuumed and much of it damaged, but we immediately implemented a preventative bio-control program in all the up-coming veg plants and clones. Four weeks later I returned to the facility and the plants in that same room were literally spotless. Within three months the entire facility was clean and spider mites were no longer an issue.

How Did We Do It?

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Californicus is a predatory mite that feeds on spider mites, but also feeds on other small mites and pollen. These mites come in small waterproof packages called sachets which can be hung from the branches. Californicus sachets were hung one per plant as soon as clones were transplanted. This means that the californicus has enough food in the sachet to stay alive and reproduce for up to six weeks, providing a protective army during that time.

(Read also: The Best Pest Control for Cannabis)

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For extra precaution we also hung a small box from each plant in veg (called bioboxes) and filled it with a small amount of Phytoseiulus persimilis (a.k.a. persimilis) each week. Persimilis is a bright orange predatory mite with a voracious appetite for spider mites, and only spider mites. Since they refuse to feed on anything else, we assume that they die within five days of not eating, and thus, release more in small amounts each week. Since the rooms and mother plants were infested with mites, we were quite safe in assuming there was food for them, at least initially.

We also made sure to sprinkle persimilis over the canopy of the clones as well, to make sure they were protected from the start. The weekly persimilis applications into the bioboxes were all the way through veg and flower, initially, but once control is achieved and the sources of contamination have been cleaned up, you can back off.

Keys to Success

Bio-control is exciting, fun to watch and can be incredibly successful. It does, however, require some patience and problem solving occasionally to determine exactly which strategies work best for your facility and growing style.

In the best case scenario, a plan should be in place before you even have plants in plugs. In the worst case scenario, you need to persevere until things have cleaned up and then implement a proactive and preventative approach. It also helps to have someone who loves bugs and is willing to look for them and release them, and you need to be patient with them when they occasionally spend an entire 10 minutes watching a predatory mite devour a spider mite. It comes with the territory, extreme bug nerds need apply!

(Read next: Keeping Bugs Off Your Nugs)

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Written by Amanda Brown

Profile Picture of Amanda Brown
Amanda Brown works with Biobest Canada as a crop protection specialist. She has 10 years of experience in the integrated pest management (IPM) industry working with food, medicinal, and ornamental crops. Amanda strongly believes that using biological control is a safer, more effective method of pest control over chemical procedures and views it as the way of the future. Biobest products are available in the USA as well as Canada, through its American distributors, Urban-Gro.

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