So what do you do when you’re facing an all-out, full-scale insect invasion? What if the attack is of microscopic proportions and you can’t even see your enemy? There are a lot of answers out there, but in the end the simpler the solution the better off your buds will be. You might even be surprised by some of our answers...

Enemy Forms

Growroom pests can take many forms. First up is the omni-present fungus whose spores are constantly floating throughout the air just waiting to settle down and nestle in. Once the right environment forms in the growroom the powdery white mildew creeps up the stalk and begins spreading onto branches and leaves.
Next there’s the microscopic bacteria, even more stealthy than spores, these particles are carried into your lab via shoes, clothes, hands or anything else transported from the outer world into the sterile confines of your grow space. Like the flu for plants, disease will wilt your crop. Branches drop, entire plants lean and as you tie up plants for support you slowly suspect these ladies are something other than healthy.
And then, of course, we have the big boys, less covert than the others, these heavy hitters cannot hide their presence for long. To growers’ dismay, these schadenfreude-ian little freaks feast on gardens relentlessly, day after day, until entire crops are destroyed. Plant after plant, bud after bud – gone. Covered by webs, cocoons, and slimy slug streaks, plants become stippled with insects ranging from mites to beetles. If your garden gets to this point, get ready for war.

Preventive Strategies

Start simple. The best way to defeat the pot pests is to prevent them from ever getting into your growroom. Seems obvious, but it is a lot tougher than you might think to deny access to microscopic organisms which you can’t see or feel. To start, you need to create the best sterile environment possible. This means sealing off your growroom to all air exchanges except for those you choose to allow (i.e., exhaust and intake fans).
Next, you need to make sure you keep your grow space clean. This means sweeping and mopping regularly, keeping stagnant water off the floor and table tops and wiping stray spray off walls and Mylar. Even more important is removing shoes upon entering the room and, if possible, wearing a shirt or overalls that you use solely for working in your garden. And, of course, wash your hands every time you go in to work or play.

Done all that and still got infiltrated?

Well, now you have some choices to make. First, identify the problem. Is it mold or disease? Are leaves rotting or fungus forming? Are there bugs and, if so, what kind? In trying to assess the situation a magnifier of 30x or higher is usually the best tool for getting a closer look. Once you know the problem you can move forward in containing, controlling and removing the culprits.

Contain & Control

This is where we begin to fight back. Prevention didn’t quite work but that’s OK, it happens to all of us. The decision on how to proceed is now based upon the exact problem. For example, if you have mold or fungus the first step is to take a look at the climate of the growroom. High humidity and poor air circulation make it easy for these problems to arise. Adding a small in-room charcoal filter will help keep the quality of air in the room sterile, especially if it is timed to sync up with the intake intervals bringing fresh air in from the outside.
Taking atmospheric control one-step further, a popular alternative these days is to install clean air generators in growrooms. These generators, sometimes referred to as UV or Ozone generators, serve two primary purposes. First, using the device as an ozone generator can be very effective in cleaning air and removing particles that may carry pathogens and other bacteria. Secondly, the UV light utilized by the generator is emitted at such a frequency (approx. 253 nm) that it will serve as a bug and pathogen zapper.
It should be noted, however, that these machines do produce ozone (O3). O3 will kill bacteria and fungi and will try to give up its third oxygen atom by oxidizing anything it can find. Therefore, when flowering or drying buds it is a bad idea to have an UV generator running anywhere nearby.
In some instances it may be a good idea for growers to examine the grow medium as well. Some mediums retain moisture and don’t drain very well, encouraging fungi to grow. Aeration of soils or Rockwool that may have compacted over time is a good idea as well.

Biological Warfare

But these solutions will only contain the problem and stop it from recurring. We still need to control the problem by removing any traces. To remove fungus, mold, disease or small amounts of bugs its best to wipe down and remove by hand. If a large problem exists you may have to bring in commercially manufactured sprays, misters or oils.
Anti-fungal sprays for plants come in all forms, including organic. If you can’t use an organic application make sure that a day or two after using chemical products you go back into the growroom and spray, flush and wipe off your plants with purified water.
An excellent homemade concoction that is easy to make consists of hydrogen peroxide (H2O2), an all-natural solution that is readily available at any drug store. Hydrogen peroxide is simply a water molecule (H2O) that has an extra oxygen atom (O2) attached. This extra atom makes H2O2 a powerful weapon because at the first chance it gets this atom will spring free and oxidize with any organic compounds it can find. This oxidation, or “fizzing”, eradicates almost all molds, fungus and bugs and is completely safe for cannabis. Still, wiping down the plants an hour or two after use is always a good idea. Never leave residue on plants longer than you have to.

For insects, applying neem oil to leaves is a great way to remove pests and prevent recurrence without harming the plants. Neem oil is a naturally occurring vegetable oil, pressed from the fruit or seeds of Neem, a type of evergreen tree from the Indian subcontinent.
Neem oil is generally sold as 100 percent organic, biodegradable and free from additives. Some growers prefer to apply the liquid by hand to individual leaves or infected parts of the plant, though many will mix the oil with warm water a spray it over entire gardens. Neem oil is an extremely powerful insect repellent and is effective in combating mealy bugs, beetles, nematodes and aphids (minute, plant feeding insects). Conversely, it is fairly harmless towards beneficial bugs such as honey bees and lady bugs.

Hand-to-Hand Combat

Speaking of beneficial bugs, sometimes your enemies’ enemy can be your greatest ally. Believe it or not, some insects are good for your growroom. Predator bugs are often released into gardens as natural carnivores, feasting on a myriad of smaller insect pests.
Ladybugs, or hippodamia convergens, are a favorite among beneficial insects because they eat over 5,000 aphids and other soft-bodied insects over the course of their one-year lifespan. Spider mites, greenflies and other types of plant lice can be treated with one release.
In addition to ladybugs, there are dozens of other insects that prey on cannabis parasites and most are easily accessible these days. Numerous websites and agricultural suppliers carry beneficial insects and can ship them to customers worldwide in a matter of days. Most varieties will become dormant during the shipping to be easily awakened by some water and warm sunlight. Conveniently, this makes for storing unused predators very simple by placing the bug container in a refrigerator where the cool temperature will again turn them dormant. These insects can live a few weeks in storage, so staggered releases during one crop are possible.
While some beneficial bugs are pretty or fun (like a lady bug or praying mantis) to have in garden, others are less appealing but still get the job done. Fungus-gnat predators, aphid parasites and green lacewing larvae are excellent front-line soldiers. Lacewing larvae attack anything they get a hold of, while parasites lay their eggs inside aphids, which then develop into leathery cocoons. The adult parasite then flies out of a round hole cut out of the mummy. Gnarly stuff, but it’s a war and in your growroom it’s a bug-eat-bug world, or a bug-eat-bud world.

Going Nuclear

We all wish it didn’t exist. We never want to resort to nuclear warfare, but the bomb is the last line of defense and dropping it in your garden is never pleasant. Yet, when all else fails, a non-conventional tactic for total annihilation of a particular growroom nemesis is bug bombing.
Bug bombs, the atomic bombs of cultivation warfare, come in many forms and have different uses. Some bombs are equipped with pesticides while some are designed for the more elusive molds and fungi. While bug bombs, or insect foggers, suffocate and kill insect pests, sulfur bombs are used to rub out powdery mildews or molds growing in gardens. Although extremely smelly and annoying, sulfur bombs are an ultra-effective solution for dire situations.
Most growers prefer to use non-toxic pesticides or chemicals when resorting to bombing. However, it is critical not to overkill and to be sure that what is being released into the air is safe for humans. A good exhaust system must be available as well.
Remember, as always, gentler natural solutions are always best for any garden or large crop. Sometimes the benefits of using something harsh to treat your plants seems very tempting, but in the end the best buds will be the ones kept as close to their natural processes as possible and that have endured little stress.


Reach out to nico@hightimes.com.