A Perfect Paring: Cannabis and IPM

Current cannabis growing norms are ideal for practicing Integrated Pest Management (IPM). Whether they are motivated by the desire to grow healthy, clean plants, or purely by regulatory constraints, the end result is the need to minimize impacts on people and the environment. IPM begins with getting your soil or soil medium right and moves on to pest prediction, trapping and monitoring; using cultural, biological and (carefully vetted) chemical controls and, throughout it all, conscientious observation and record-keeping to plan for the future (for more on all this see our IPM page here). All of which works perfectly for a well-run grow.

A good portion of IPM practices are pretty straight forward and easy to initiate, even for beginners to the field. The biological controls part, however, can be daunting (if not downright confusing) even for seasoned growers. Here at ARBICO Organics, our mission is to guide growers towards these best practices and help them maintain smooth and efficient biological control using the proper beneficials for the job.

Any IPM program no matter the crop or growing style, works best when it’s started before you even touch a plant. Soil/soil mediums should be pathogen-free, yet full of microbial life, before any plants go into it. The introduction of beneficial nematodes and/or Stratiolaelaps scimitus (Hypoasis miles), for instance, can offer early, pro-active protection from a long list of insect pests. Hypoasis miles specifically preys on the dreaded fungus gnats. A little bit of pre-emptive treatment early on can save you financial and emotional hardship later.

Another necessary step to be taken from the start is close monitoring of the grow environment. Not only to ensure that plants are in optimal growing conditions, but also to spot pests and pathogens as soon as they appear. Biological controls work best over time, so it is important to apply them at the first sign of trouble. This is often the stage where growers who are new to biological control falter. We have been conditioned to reach for a killing spray as soon as we see a bug, so there is sometimes a learning curve and a change in expectations that needs to happen. Instead of squishing the bug instantly, observe and identify it, discover where it came from, and determine if there is a population living in your plants. Armed with the specific knowledge of what you’re up against, you can move on to your
next step – choosing the beneficial to use - with confidence.

Knowing the pest you need to control is important, but when choosing the right beneficial agent for your specific needs your growing environment needs to play a role in your choice as well. Certain beneficial insects have specific temperatures and relative humidity requirements to perform their best, while for other insects the amount of light can affect their biological functions. Outdoor growers are restricted in their choices by their environment, whereas indoor growers have more options, including modifying their conditions to ensure that the beneficials thrive. There are some biologicals that can work indoors and out for most situations, but for optimal control, you’ll want the best beneficial for the specifics of your grow. This does not mean that the “all-purpose” biologicals are no good, only that they are but one part of a multi-tool IPM approach.

There is a wealth of beneficial/predatory insects and organisms that work extremely well to control pests in cannabis cultivation. Some of these include predatory insects and mites, parasitic wasps, microorganisms, and the afore-mentioned beneficial nematodes. Amongst the predatory insects, there are generalists (non-selective) predators and specialist (targeted) predators. The generalists aren’t picky eaters and go after lots of different insects in various life stages. They include Assassin Bugs (Zelus renardii), Green Lacewings (Chrysoperla rufilabris), Minute Pirate Bugs (Orius insidious), and even Ladybugs (Hippodamia convergens). The specialist predators have specific dietary proclivities and either consume or parasitize particular prey. They include Mite Predators (Phytoseiulus persimilis), Aphid Wasps (Aphidius colemani), and the Fungus Gnat Predator Hypoasis miles that I mentioned earlier. Unless you have used beneficial insects before or you are a professional in the good-bug field, it is perfectly normal to not know what to choose. That’s what we are here for. Likewise, if you can't identify the insect plaguing your plants, take a picture of it and give us a call (our specialist will tell you where to send it). Armed with the picture and your input, it is usually very easy for our pros to figure out your problem.


Once you have determined which beneficial to use, it is essential that you treat with the right amounts at the right time and keep it up. Continuity and scheduling should be your mantra at this point. Most pest insects reproduce at an energetic pace; you will need to outpace that reproduction with scheduled applications of sufficient amounts of predatory insects. Additionally, some specialist insects require a lead time in order to receive them, so you will need to plan to cover that time frame. Using beneficial/predatory insects is very much like taking antibiotics – do not stop your treatment just because the condition seems better; it is essential to complete the prescribed course.

If you have questions (and why wouldn’t you?), I encourage you to dig into our website. A good place to start would be our Hemp/Cannabis page. We also have a Cannabis Catalog with products that have been hand-picked for the industry. We have worked hard to provide comprehensive content to inform and guide any visitors, and I feel confident that you can begin your road to IPM through our pages. But, for those of you who prefer a person-to-person exchange, our Bio-Control Specialists are also available for free consultations Monday-Friday from 8:00-4:30 pm. (we are on Mountain Time). Let them help you figure out what will work for you. For more on cannabis and IPM, you may also be interested in reading “5 Questions with Arianna Weisbly Taylor” in the July 2020 issue of Cannabis Business Times.

Take Care.
Submitted by Pam