Chapter 16

Get Your Pest Control

You need pest control products to both prevent and kill cannabis pests and diseases. Inevitably home growers encounter various pests and plant diseases when growing cannabis year round, so it pays to be prepared to handle it. Dealing with pests and disease is a big part of growing cannabis at home and shouldn’t be taken lightly. Crops can easily be obliterated by pests and no one likes losing a crop. You lose more than just your crop, you lose money and time, too. Do not worry though. A simple weekly application of preventative sprays will keep your home grow pest and disease free. More on that later. First, let’s go over the common cannabis pests and diseases to be familiar with.







  1. Fungus Gnats
  2. Powdery Mildew (disease)
  3. Spider Mites
  4. Aphids
  5. Thrips
  6. Mealy Bugs
  7. Whitefly
  8. Scale
  9. Rust (disease)
  10. Leaf Septoria (disease)
  11. Botrytis (disease)
  12. Hop Latent Viroid HpLVd (disease)


Fungus Gnats

Fungus gnats are the least harmful pest on this list, but they can be a big nuisance. Especially when you have a full blown infestation or see dead fungus gnats stuck to the trichomes on your flowers. Don’t worry though, you can use tweezers and pull the buggers off. You can also prevent a full blown infestation by dealing swiftly with them at the first sight of just a few fungus gnats.

Some people mistake fungus gnats for fruit flies. While they may look like fruit flies, they are not fruit flies. Enough about fruit flies.

Fungus gnats can be easily seen flying around your plants, but they actually live and breed in the soil. You see, fungus gnats survive and thrive in moist organic matter. They feast organic matter in the soil. How do they get there in the first place? They either show up in the soil you purchased, or they show up because the soil has been too wet for too long from overwatering. Overwatering always leads to fungus gnats when you’re growing indoors at home. To avoid brining home fungus gnats in new bags of soil, be sure to inspect the soil thoroughly before purchasing it. If you’re ordering soil online, there’s some risk involved, but the vast majority of quality bagged potting soil is not infested with fungus gnats.

There is a quite a difference between having a few fungus gnats and a full blown fungus gnat infestation. When you see a few fungus gnats, deal with the issue immediately and the problem will go away. If you ignore them, and continue to overwater, you’ll end up with an infestation. With a fungus gnat infestation, giant clouds of fungus gnats will swarm your plants and grow tent. To eradicate them, you can use a shop vac and suck the fungus gnats out of the air. Infestations are bad news because fungus gnats will eventually end up eating the roots of your plants causing severe problems for plants. This is rare however, because it’s quite near impossible to not see fungus gnats before they develop into a massive infestation. They are extremely easy to spot, unlike spider mites and thrips which hide underneath the leaves and often go undetected for weeks.

Fungus gnats are easy get rid of, if you act sensibly when you first begin to see them. As soon as you see a few fungus gnats, consider the fact that you most likely have been overwatering. Your first steps should be to stop over watering, spray the top soil with a pest killing spray, and then begin using Mosquito Bits in the soil. The Mosquito Bits product consists of small hard brown granules that can be added to your water and stirred, or it massaged into the top soil and watered in. This safe product kills the fungus gnat larvae in the soil and effectively ends the cycle of fungus gnats. To be clear, it doesn’t kill the adults flying around, it only kills the larvae. Mosquito Bits comes in bags and plastic bottles, and the label clearly states the product is designed to control fungus gnats (as well as mosquitoes.)


IMPORTANT: If you are already overwatering, don’t water again with Mosquito Bits right away. Instead, use Organocide or Trifecta Crop Control and spray the top soil with it. After a few days of the soil drying out, then use Mosquito Bits with your next watering.


Lastly, many growers like to hang yellow sticky traps to catch fungus gnats, but they are primarily used to help identify when fungus gnats are present in the garden. Since it is so easy to see fungus gnats flying around, using them as an identifier seems to be overkill to me.  I find that yellow sticky traps aren’t necessary for new growers to use, but they can be beneficial if you decide to use them. I personally don’t bother with any yellow sticky trap expenses, but some people really like to use them. They are a “get to,” but certainly not a “got to.”

Powdery Mildew

Powdery mildew tainted cannabis is unacceptable. Do not consume or smoke cannabis that has been contaminated with powdery mildew. Not only will it taste horrible, it is dangerous especially to those with compromised immune systems. Side effects of consumptions could include flu like symptoms. Licensed sellers of cannabis get their product lab tested to verify it is powdery mildew free for good reason. It is NOT safe to consume!

Powdery mildew is fungal disease that haunts home growers because it is quite difficult to eradicate once it becomes a problem. But it is preventable and much easier to prevent powdery mildew than kill it. So focus on prevention, prevention, prevention! Learn how to prevent powdery mildew and how to handle a powdery mildew outbreak in your home grow below. But first, how does powdery mildew get into your grow tent? Powdery mildew comes into your grow tent through the air. Subatomic powdery mildew spores ride air currents and eventually fall onto plants and infect them. A few days later, splotches of white powdery mildew on the plant’s leaves and branches will be visible to the naked eye. It’s all downhill from there.

You won’t know that you have a powdery mildew problem until it is too late when you aren’t spot-checking your plants daily. Be proactive with daily observation (inspect your plants!) and catch it early before it blows up and ruins your crop completely. In a matter of a week, powdery mildew can spread to every single plant easily. So stay vigilant with spot checking your plants.


Prevent powdery mildew:

To prevent powdery mildew from becoming a problem in your home grow, focus on two things: humidity control and preventative sprays. You can prevent powdery mildew simply by having a proper humidity % in your grow tent. Your ideal humidity target should be 50 – 55 % RH. If humidity is over 60% RH, then powdery mildew spores can easily survive and spread. Ensure you have 50 – 55% RH in all stages of growing (VEG, FLOWER and HARVEST) to help prevent powdery mildew outbreaks and infestations.

You can also use a safe preventative spray to prevent powdery mildew. There are many foliar sprays available to combat powdery mildew for use in VEG and FLOWER. Growers use them unwaveringly in VEG, however in FLOWER, not so much. Most growers do not spray flowers, or they only spray their flowers up until FLOWER weeks 2 and 3. This is because they don’t want their flowers to have any undesirable bad flavors on their final product, and they don’t want to damage or burn their flowers. Many sprays claim they can be applied up until day of harvest, but cannabis growers take this with a grain of a salt. If you aren’t smoking your final product, then you can spray the flowers until the day of harvest without hesitation.

The recommended sprays shared below are not only going to help with preventing and killing powdery mildew, they also are going to help prevent and kill bad cannabis pests, too.


What to do with Powdery Mildew in VEG:

If you see powdery mildew on your cannabis plants in VEG, follow these important steps below.


Step 1.

Immediately turn off all the grow tent fans. (The fans are only going to blow the spores around and hasten the infestation, so turn them off.)


Step 2.

Remove infected leaves! Grab a garbage bag, clean trim scissors, and put on plastic gloves. Cut away all the infected cannabis leaves and branches, but do so carefully so you don’t cause the powdery mildew patches to blow around. After you’ve removed all the infected leaves, tie up the bag and discard it as far away as possible.

How many leaves can be removed? A lot. Even if you have to remove ½ the leaves or a little more, your plant can still recover. If the powdery mildew covers more than 3/4 the leaves, I recommend chucking the infected plants out and focusing on cleaning your grow tent and the room your grow tent is in.


Step 3.

After you’ve removed all the infected leaves, generously spray the cannabis plants with sprays like Trifecta Crop Control, Organocide, as well as Neem Oil or Horticultural Oil. Be sure to spray under the leaves, on top of the leaves, as well as the branches and stalk.


Step 4.

Deep clean your grow tent with a bleach/water solution. It may take an hour to do it, but it is worth the effort. Since you’re using bleach, wear gloves, a mask and your grow glasses to be safe. Also be sure there is adequate air flow so that you, your family or your pets aren’t exposed to the hazardous fumes. Thoroughly wash the tent walls and wipe down the poles and fans, too. If you have dirty old fans, go ahead and upgrade a buy a new 6″ exhaust fan or new clip on fan.


Step 5.

Asses and reassess your humidity levels in your grow tent and try to achieve a 50 – 55% RH. If you can’t get below 60% RH, I wouldn’t be too worried. If you are between 65 – 70% RH, I would worry and take steps to lessen it with a strong dehumidifier, by opening grow tent doors, and using more exhaust fans or a stronger one.


Step 6.

Evaluate your airflow in the tent. The airflow goal is to make the leaves move lightly (dancing) from air flow. This means you should not blast the plants with strong winds from big fans. One or two clip-on fans, per 4 x 4 tent, is all you need. Have the fans at an angle pointing down towards the plants ideally.



What to do with Powdery Mildew in FLOWER:

Powdery mildew outbreaks in FLOWER phase are extremely hard to get rid of. It’s worse to deal with compared to getting it in VEG. Unfortunately there’s no silver bullet to eliminate the problem. Even when you try to mitigate a powdery mildew infestation with best efforts, success is not guaranteed. When you have powdery mildew in FLOWER, you can follow the  steps 1 – 6  outlined above with a few tweaks.

If you’re in FLOWER and powdery mildew is on every single plant, every leaf, and all over the flowers, then I recommend you trash them, clean your grow space, and start over fresh. In fact, if you see powdery mildew all over your actual flowers/ buds, you should throw them out. You can cut the infected flowers/buds away, but if you have to do this all over the plant (or plants), I recommend discarding them, cleaning, and starting over. Also, I absolutely do not recommend ever soaking powdery mildew contaminated flowers/buds in anything to kill the powdery mildew so that you can consume it later.

Sometimes when you try to salvage your garden from powdery mildew, you’ll think you’ve finally done it, but then it comes back. That’s why I said earlier on the powdery mildew haunts home growers. It really does!

If you keep getting bouts of powdery mildew after you’ve removed the infected leaves, sprayed the plants, and cleaned thoroughly, then it is time to step up your powdery mildew prevention game. Scrap the plants, re-clean everything, and search outside your home for close potential sources of powdery mildew infestations that might be infiltrating your home. If you have bushes or plant life outside with powdery mildew, then you need to work to remove them from the premises. Either chop it down, bag it up and discard it, or attempt to use powdery mildew killing sprays on them.

Next, get a powerful air purifier that uses photocatalytic oxidation to safely kill (explode) powdery mildew spores in the air. Nothing is as aggressive at killing airborne powdery mildew spores than AiroClean420 air purifiers are. Read more about using them in your home grow at the end of this chapter.




Don’t give these pests an inch or they’ll take a mile. Use pest control products regularly and you won’t even give them an inch. However, if you’re under attack and you see a bunch of bugs under a leaf, then remove that leaf and discard it ASAP. Don’t give those buggers a chance to survive your next spray down. Always remove any heavily infested leaves from the premises.

Whether you’re in VEG or FLOWER, all of these intrusive insects are very bad for cannabis plants. These pests should not underestimated. They are creepy, ugly, detrimental buggers and cannabis plants are their stomping grounds. Don’t say I didn’t warn you. There are actually many different types of spider mites and aphids out there, so depending on where you live, you’ll encounter different ones across the world. All of these pests replicate fast and would love to make a home in your cannabis garden. Look under the leaves to find these critters and their eggs. Feel free to pinch them, if you dare. Personally, I’ll pinch an aphid, or thrip, or whitefly, but if I see spider mites, mealy bugs or white flies, I’m not touching them. They are too creepy-crawly-gross for me!

But you don’t have to worry, you’ll be regularly preventing pests with ease with Organocide and Trifecta Crop Control, my two favorite pest control products. They both work very well, however Organocide costs less. Yet it smells pretty bad. Trifecta costs more, but smells quite nice (if you ask me.) I also recommend rotating pest control products like Horticultural Oil or Neem Oil in once a month. As a heads up, pests can develop resistance to pest control products. Using and rotating different pest control products is a recommended practice to prevent that from happening. At the very least, use one of the above products, if not 2 or 3. Never apply them at the same time and stick to a 1x a week regimen unless you’re battling an infestation, in which case you can apply and rotate sprays every other day to get results.




Rust, leaf septoria, and botrytis are common fungal diseases that commonly impact cannabis. Powdery mildew is the most common fungal disease, but all of these can wreak havoc on cannabis plants. As a hard rule, never consume cannabis flower in any capacity that has botrytis, bud rot or powdery mildew. Rust, leaf septoria, and botrytis are all difficult to eradicate and humid conditions allow these plant diseases to exist and spread rapidly. In VEG, if you eliminate the disease and the plant gets healthy again, you can confidently flip to FLOWER. It is not recommended to flip to FLOWER if the plant in VEG has rust, leaf septoria, or botrytis. Get the plant healthy first before flipping to FLOWER.

You can avoid these fungal plant diseases by keeping a low 45% – 55% RH in your grow tent. Maintaining a low humidity percentage in your grow tent can be a challenge, but later in the book you’ll learn how to raise and lower humidity.

If your plants have rust, leaf septoria, or botrytis, the first thing to do is to turn the fans off, then remove the infected leaves to help stop the spread of disease. If you’re in VEG phase, then you might be able to save your plants depending on the severity of the outbreak. If you’re in FLOWER phase, then you might be able to ride out a minor episode. However, if an outbreak affects your cannabis flowers, do not consume them.

Botrytis, often called gray mold, is the culprit behind gross “bud rot” on their flowers/buds. Bud rot starts inside the buds, but eventually the flowers/bud look dead and bruised. As soon as you see any dead, grey, brown, black, bruise-colored discoloration, you should trash the entire flower or branch the flower is on. Do this when you see even the slightest discoloring / bruising.

Rust is a fungal disease that will cause you plant to look like red rust has been coated and splattered on your leaves. The discoloration on leaves is noticeably rust-colored.

Leaf Septoria, or “Yellow Leaf Spot” as some call this fungal disease, causes your leaves to become spotted yellow and brown. Eventually the whole leaf turns splotchy yellow, then brown, and eventually it dies off completely.

Organocide and Trifecta Crop Control, as well as Horticultural Oil and Neem Oil, will help prevent and kill plant fungal diseases. Copper Fungicide is an additional fungicide product to assist in controlling plant fungal attacks. You don’t mix these solutions, or apply them at the same time. Rotate the products in between applications.




Trifecta Crop Control smells nicer than any of the others and it works very well. But Organocide also works very well and costs less, so if you’re looking to keep your expenses down, get Organocide. I also recommend neem oil and horticultural oil.

These products are available in concentrate form or ready-made sprays. The concentrate option is always the most cost effective, but you’ll have to purchase some empty spray bottles. Spray bottles break easily, so don’t be surprised when they do. Nevertheless, you save a lot of money by getting the concentrates and mixing the solution yourself. Just mix the solution with water, shake, and spray. Of course, follow the instructions on the label. Some instructions have specific dosage requirements for “prevention” and different recommendations for “infestations.”

The ready to spray option works great too, but you pay a little more.

When applying pest/plant disease controls like the above mentioned, use gloves as a precaution, and do not spray your plants while the fans are on. Also turn all the fans off before applying. This way you won’t accidentally get sprayed in the face by your pest control spray.

To store your pesticide, miticide or fungicide products properly, always keep them out of sunlight, and keep them away from food, including pet food. NEVER pour unused product down any indoor or outdoor drains.



Organocide ingredients include sesame oil, fish oil and soybean extract, and Organocide a recognized insecticide, miticide and fungicide. It works by smothering insects on contact. Once it dries, there is a film and residue left on the plant, which continues to repel and kill insects and their babies. Organocide is OMRI certified, and upon mixing can be stored for 30 days of ongoing use. As a preventative, you only need to use it every 10 – 14 days. It is available as a concentrate or ready to spray bottle.



Trifecta Crop Control is considered a contact pesticide, which means it will kill mites on contact. Trifecta Crop Control ingredients include thyme oil 14%, clove oil 10%, garlic oil 9%, peppermint oil 4%, corn oil 3%, geraniol 3%, citric acid 2%, rosemary oil 2%, as well as soap, water, soap, isopropyl alcohol, and vinegar. These essential oils acts as a repellent, a suffocant, a reproductive inhibitor, and a miticide and fungicide. Trifecta Crop Control is available as a concentrate or ready-to-spray. If you get the concentrate option, there are instructions for “prevention” and “infestation.” As a preventative, you only need to use it 1x – 2x a week.

Trifecta Crop Control meets the criteria for organic under USDA guidelines and most certifying organizations.








How To Apply Sprays:

Ready to spray options are the easiest. If you purchase the concentrate version, you’ll need to make sure you follow the label’s instructions when you mix it so that you don’t add too much, or not enough.

When you’re ready, pull your plants out of the grow tent to apply the foliar sprays. Hands down you’ll do a much more thorough job this way. An average house light will be OK to spray plants under since they are not high intensity grow lights. However, if you spray your plants in the grow tent, do not keep the grow light on because many grow lights will burn / bleach leaves coated with foliar sprays cooking in intense lighting. We don’t want that!

To spray effectively, spray thoroughly on the tops of the leaves, under the leaves, as well as on the the stems, branches and stalk, too. Most bugs live underneath the leaves, so do not forget to spray under the leaves. Coat your plant generously with your sprays. You can also spritz the top soil and the sides of your pot.

Air Cleaner by AiroClean420

Home growers can prevent powdery mildew like commercial indoor farms do with Airo Home Hobby, a proven air purifier made by AiroClean420. The Airo Home Hobby is a smaller model of the commercially sized AiroClean420 units. For several years, commercial grows across North America have been relying on AiroClean420 to prevent powdery mildew in their facilities. Today, home growers can too.

Although the investment up front is $995, the Airo Home Hobby will last 8 – 10 years with proper maintenance, plus it comes with a 3 year warranty. I have personally used Airo Home Hobby for years and it is truly a game changer for home growers who struggle with powdery mildew. I used to get powdery mildew frequently because my home is nestled in a tropical canyon ripe with plant fungal diseases. With the doors and windows open all the time, I got powdery mildew all the time, even with all the sprays. After hanging Airo Home Hobby in my room, I haven’t had powdery mildew since. It’s been over two years! I still do my preventative sprays, and try to keep the humidity down, but Airo Home Hobby was the missing link in my quest to be powdery mildew free.

As long as your tent is at least a 4 x 4, you can hang one in it. They also can be used in any bigger grow tent size, or any grow room up to a 12 x 10 x 10 space. You can also hang it in the room your grow tent is in. Ideally, you don’t want to exhaust air outside the room because that’s clean, purified air you’ve got when you’re running Airo Home Hobby. If you have to exhaust hot air because of heat issues, do it intermittently instead of non-stop.

Airo Home Hobby works by sucking in air and anything it is contaminated with like powdery mildew spores. PCO technology then goes to work inside the unit to explode and eliminate the contaminants. PCO stands for photocatalytic oxidation and is a truly remarkable invention. Subatomic fungal spores get exploded and turned it into water vapor with trace amounts of CO2. The technology is used in other applications such as hospitals, spacecraft, wineries, and more.

Airo Home Hobby is completely safe to use and only draw 100 watts. Once you hang one, just turn it on. A small green LED light will shine, but green LED lights do not affect your flowering plants, so don’t worry about that light if you’re hanging the unit inside your grow tent. When the unit needs yearly maintenance, you’ll get a reminder from the company. The maintenance involves changing a filter that protects the PCO technology, and changing inner the light emitting bulbs that work with the PCO technology.

Order Airo Home Hobby air cleaner today at and get a free surprise gift from Green Carpet Growing and AiroClean420.

Airo Home Hobby displayed in a grow tent




Marc Eden’s DIY Cannabis Cultivation Book For Beginners
Published by Green Carpet Growing, Inc.
San Diego, CA 92103
© 2021 Green Carpet Growing, Inc
All Rights Reserved

No portion of this book may be reproduced in any form without permission from the publisher, except as permitted by U.S. copyright law.

For permissions contact: marc(@)