The Grower’s Guide to Integrated Pest Management • Grow Magazine

Whether you’re a large-scale commercial grower or a small-scale craft grower, protecting your valuable crops is usually the first thing on your mind. You can find lots of ways to protect your plants from bugs and other issues, but if they aren’t sustainable, it’s going to cost you in more ways than one in the long run. If it’s not an environmentally friendly method, you’re hurting your own growing environment. And if it’s not cost effective, you’ll quickly eat into your profit margins, making it hard to maintain your business.

That’s where integrated pest management (IPM) comes in. IPM is a holistic approach that is fundamental to pest and disease management in all facets of horticulture and agriculture. The strategy that focuses on long-term prevention and suppression of pest issues through a combination of techniques like biological control, habitat manipulation, and judicious use of pesticides when absolutely necessary. Rather than simply responding to pest outbreaks with heavy pesticide applications, IPM promotes proactive habitat management and monitoring to prevent pests from becoming a problem in the first place.

To find out more about why IPM is important, how it works, and how to transition to an IPM if you’re not already using one, I spoke with Mike Burns and Danny Murr-Sloat. Murr-Sloat is founder at AlpinStash Genetics & Consulting, with experience in grows from 2,500 to 480,000 square feet. Burns is cultivation manager for ARL Healthcare, a full production medical and recreational facility with multiple cultivation sites and dispensaries in Massachusetts. 

Think of IPM as a triangle, with the foundational practices as the base of the pyramid leading to the tip of the triangle which are the things you would do as a last resort.

Exclusion
Cultural Controls
Mechanical Controls
Biological Controls
Chemical Controls

Prevention: Exclusion & Quarantine

As with everything, prevention is key. A big part of exclusion is establishing the operational activities. “It all starts with a culture of cleanliness,” says Burns. Ensure that your facility is clean and sealed off. Establish protocols for cleanliness when people are leaving and entering the facility. Establish a sanitation protocol. You could have a high-pressure air shower that everyone walks through to remove any contaminants residing on clothing or hair. Floor-mounted sticky mats swipe contaminants from shoes. Shoe covers are another option. Everyone’s got a different standard and procedure and that’s ok. But establish your procedure and stick to it.

Keeping pests and diseases out of the grow environment or facility is the biggest first step. “Quarantine any new incoming plant material,” says Murr-Sloat. “At least three weeks and you might want to scale up depending on what phase of growth it is in. For example, my first choice is always to receive plants from a vetted tissue culture lab. If I receive cuts from another source, I always prefer to receive root cuts and root them myself because then I know I’m not getting any root-borne pests like root aphids, which are super gnarly. And if I have the luxury, I would require any incoming material to have gone through a disease screen with a certified lab to make sure you’re not getting any of the really scary diseases like HLVd.” 

Buy from trusted sources, but even then, quarantine. Even with the best of intentions, damage can still be introduced if you’re not careful. “It’s an ounce of prevention, which I think needs to be a hard and fast rule in a facility,” says Murr-Sloat.

For pests, beneficial insects are usually enough and Murr-Sloat doesn’t recommend preventative insecticide sprays if no known pest is present. “It’s a different story when it comes to fungal disease,” he says. “These can be devastating and go from a mild issue to a huge problem very quickly. I’m a big fan of regular use of biological controls such as Double Nickel (beneficial bacteria) and Regalia (beneficial fungus) and hydrogen peroxide–based products. I recommend only using foliar-based preventative sprays in veg and early flower.  I stop preventative applications when the buds begin to set, usually between day 11 and 14.”

Monitoring and Identification

Educate yourself on what pests are that you might have to combat, what they look like, what their symptoms look like, and how to deal with them. Yes, that is a lot to learn! But it’s knowledge that will pay dividends in the long run. Common cannabis pests like spider mites, fungus gnats, thrips, and aphids can cause devastating damage if left unchecked. Being able to quickly identify them, understand their life cycles, and recognize the first signs of an infestation is key. You need to know what pest damage looks like — whether it’s spotting on leaves, stunted growth, or other symptoms.

IPM requires an ongoing commitment to education and diligent record keeping. But determining which IPM methods work best for your specific cannabis cultivars and facility will ultimately result in a healthier, more sustainable crop.

“This means performing visual inspection on the plants, or using other detection methods,” says Burns. Sticky traps can be placed around the facility to catch pests. Computer vision technology uses algorithms and sensors that can detect pests and diseases. Apps can analyze a photo of a plant and tell you what the problem might be.

“Even with all of that, every grow operation should employ a level of visual inspection by human staff who cross check,” says Burns. “Technology can still fail at the end of the day. And, I think, the more honed in you are with your garden as a human, the more easily you will be able to identify problems with the naked eye.” 

Burns says it’s nice to have charts, posters, a book, or other visual reference guide to pests and molds in the garden for the people who are doing the daily checks to reference. It’s also helpful, Burns says, to invite someone on your staff who is more knowledge about pests to provide general coaching to other team members who are newer to the industry. “So everybody is on the same page and looking for the same things,” Burns says.

Controls

Once you’ve identified culprits you may have to face, having a comprehensive IPM plan will guide you on the appropriate cultural, biological, and if needed, chemical control methods to bring that specific pest under control. The IPM approach provides a full toolbox of tactics beyond just spraying pesticides.

For example, you may need to adjust environmental factors like temperature, humidity, or airflow to disrupt the pest’s life cycle. Or introduce beneficial predators like ladybugs, lacewings, or parasitic wasps as a biological control. IPM utilizes a variety of control methods to manage pests. These controls can be grouped into four main categories:

Cultural Controls
These are practices that prevent and reduce pest populations without relying on pesticides. Examples include proper sanitation, removing pest habitat, using pest-resistant cannabis cultivars, adjusting temperature/humidity levels, and maintaining optimal soil conditions. Crop rotation and strategic planting/harvest schedules also fall under cultural controls.

Physical / Mechanical Controls
These involve manually removing pests or using non-chemical devices to make the environment unsuitable. Hand-picking pests, using sticky traps or barrier films, and disrupting pests through temperature extremes or vacuum devices are some physical/mechanical options for cannabis.

Biological Controls
These involve the use of living organisms to control pests. For cannabis, common biological controls include beneficial insects like ladybugs, lacewings, and predatory mites that feed on pests like spider mites, aphids, and thrips. Insect-killing fungi and nematodes can also act as biological pesticides.

Burns’s facility uses only biological control methods, including beneficial insects. “We don’t have a pest issue but we use them for prevention,” he says. Massachusetts is a very strict state when it comes to using pesticides, but Burns’s facility in general also prides itself on growing naturally and being transparent with their customers about their grow methods.

“Many people now are looking for pesticide-free cannabis,” says Burns. “They want a reliable clean source and not something that is being sprayed with chemicals.”

Burns uses beneficial nematodes, which are microscopic worm-like creatures that will live inside of your media. These feed on flying insects such as whitefly larva. Some rove beetles feed on a variety of insects, while others target specific pests such as root maggots.Minute pirate bugs feed on thrips, aphids, spider mites, and whiteflies. 

Amblyseius swirskii is a predatory mite that is attracted to thrips and whiteflies. These mites can be purchased in bottles or “sachets.” The sachets or packets that are specialized controlled release systems that are hung or distributed around the crop canopy. As the fungus gathers on the bran inside the sachet, it allows the swirski mite population to establish itself while feeding on the mold mites and fungi. The fine mesh permits the mites to exit the sachet and disperse throughout the plant canopy to feed. 

There are different layers to knowing how the bugs work, also. For instance, the adult forms of ladybugs and green lacewings eat aphids, but the larval forms of both eat many more aphids. But, introducing larval ladybugs means that you will eventually have adult ladybugs that may find their way into other parts of your grow — maybe even into the buds of your plants — and then die. Hypoaspis miles are the soldiers of soil, feeding on soil-inhabiting insects, mites, and all stages of springtails, fungus gnat larvae, thrips pupae, pathogenic nematodes, and some weevils. There are many places online where beneficial insects can be ordered. 

Another biological method involves the concept of banker plants. Banker plants are plants that are not the same as your crop plant that are attractive to your beneficial insect. The plants support the beneficial insect so that they can protect your crop plant.

Chemical Controls
As a last resort, chemical pesticides may be used, with preference given to botanically-derived, biodegradable products over synthetic formulations. Even approved pesticides should be carefully rotated and applied judiciously to avoid resistance. Within IPM, chemicals complement and are minimized by the other control methods.

“There are definitely some nasty pesticides out there but there are also some fairly harmless things like the hydrogen peroxide–based fungicides,” says Murr-Sloat. “But even with that, you don’t want to get a faceful of it in its concentrated form.” Make sure your employees also have appropriate PPE and knowledge of the substances they are using. Insist that the directions for application be followed — doing so is a federal law.  Use the right control for the problem, pay attention to PPE requirements, return entry intervals, dosing, application methods, pre harvest intervals, and what to do if accidental exposure occurs.

There can be a tendency to overreact and go “broad spectrum,” throwing a bunch of things at a problem without completely understanding it. Take the time to get a correct identification or diagnosis. “Look under the microscope, look at the antenna structure,” says Murr-Sloat. “If you see a mite in the soil, be sure it’s not one of your predator mites that you released in the soil.”

Do Nothing
If the pest problem is not causing significant damage, it’s possible that no intervention would be required, although Murr-Sloat says he would never recommend doing nothing. 

“It’s important to know and understand pests and diseases so you know how to ramp up your approach,” he says. “And to know if the problem you are seeing is a sign or symptom of a pest, or something like mechanical damage, enviro damage, or funky genetics. With a proper ID, you can know when to go full nuclear on an issue and when to not overreact and do more harm.”

The core principle is using a balanced, integrated combination of these controls based on monitoring and record-keeping data. Allowable practices largely depend on cultivation regulations in each legal market. 

Key Word: Management

“The key word in IPM is management,” says Murr-Sloat. “It’s common, especially in a large-scale operation, to have an ideal of eradication or elimination, but management is the realistic goal.”

If you see a pest, an ideal approach would be to slowly ramp up your efforts against it and use chemical controls only if everything else hasn’t worked. Beneficial insects do a great job as a preventative and as a management tool if you have low-level infestations. But, says Murr-Sloat, if you have a more moderate infestation or something that is suddenly overwhelmingly present, and you don’t have a population of beneficials built up, using bugs alone might not be enough. “Within a couple of weeks of unchecked population growth, a lot of these pests can just explode,” he says. 

All the more reason to study up and know your pest. “If you identify the pest correctly and you understand its lifecycle, that gives you really good opportunities to specifically target it,” he says. One example is that of the common pest thrips, which have an instar stage that lives on leaves and a pupa stage that lives in soil. “So if you know that, you can target them not only on the leaf, but also in the soil, where they have to go to be able to migrate back up on to the plant,” Murr-Sloat explains. 

Another key concept of IPM is the “disease triangle.” This means that in order for a pest to really take hold, it has to find the right host and the environmental conditions that favor it. Exclusion is hard to achieve, so often the best chance for success is to focus on other things. “Keep your plant health tip top, and then keep the environmental conditions favorable to plant health and not favorable to the pest or disease,” says Murr-Sloat.

Getting Started

As you can see, while IPM is a straightforward concept, there is a lot involved with it. If you’re embarking on adding IPM to your facility, seek out a consultant to help you get started. Murr-Sloat, who offers this type of consulting, understands that working with a consultant is an investment, but it can also save a lot of headache and heartache. “A consultant can set you up with a really good IPM program that’s been proven in the commercial space,” he says. “When you consider saving the headache and money losses and the crop preservation that will come from it, it’s a great investment. Even if that wasn’t a service that I offered, I would still recommend that you work with someone knowledgeable because this is so fundamental to a successful facility that this is something you really want to make sure you’ve got right. In the end, it ends up being a trivial expense.”

In addition to that, start to think like a horticulturalist and gather scientific knowledge. Take pest and disease classes. Get to know the resources at your local Extension office.