If you have grown cannabis for any amount of time, you've undoubtedly dealt with bugs. If you haven't you will. With any crop grown in a monoculture, pests have figured out its a great host to survive with. There are pesticide options, but use caution with all.
Pesticides and Cannabis
The use of pesticides in cannabis cultivation is highly regulated, particularly in legal markets like the United States, Canada, and Europe. Different regions have established guidelines and testing standards to limit the types and amounts of pesticides that can be used. In legal states in the US, for example, cannabis cannot be legally sold if pesticide residues exceed allowable levels, which is why cultivators must be careful to use pesticides that are not only effective but also safe for human consumption. Pesticide levels also accumulate in oils, distillates, and isolates - so if you plan to make extracts your flower - beware. Overall, the vast majority should not be used while plants are in flower.
In addition, there are few pesticides actually labeled for cannabis use. The process takes time and money, and many companies don't bother. Oregon and Washington both have fairly comprehensive lists of what is currently approved for use on cannabis, and are great databases to check out if you are curious.
Integrated Pest Management
The best weapon against pests is prevention. Starting with clean seed stock, in a clean room or greenhouse, with fresh soil is a great way to prevent outbreaks. Keep visitors to your fields or rooms at a minimum, inspect plants regularly, promote beneficial insects, and rigorously inspect and test any new plants before introducing them to your environment.
If you find yourself in the midst of an infestation, here are some common treatments to look into. Above all, do your research and pay attention to the labels.
Common Pesticides in Cannabis Cultivation
The types of pesticides used in cannabis cultivation vary based on the pest problem being addressed, but they generally fall into a few categories: insecticides, fungicides, miticides, and organic pesticides. Here are some of the most commonly used pesticides in cannabis cultivation:
1. Pyrethrins and Pyrethroids
Pyrethrins are natural insecticides derived from chrysanthemum flowers, while pyrethroids are synthetic versions of the same chemicals. These pesticides are among the most commonly used in cannabis cultivation due to their broad-spectrum effectiveness in controlling a variety of pests, including aphids, whiteflies, and spider mites. Pyrethrins work by disrupting the nervous system of insects, leading to paralysis and death.
While pyrethrins and pyrethroids are effective, they can also be toxic to beneficial insects, such as bees, and can cause health concerns if not used correctly. In some regions, pyrethroids have been banned due to their potential to leave harmful residues on plants. Treated flower should not be used for extractions, as pesticide levels accumulate during processing. If insect populations are not totally eradicated after treatments, they can become tolerant to pyrethrins and pyrethroids over time. If you are a commercial cultivator, do your research before treating plants at any stage.
2. Bacillus Thuringiensis (Bt)
Bacillus thuringiensis is a soil bacterium that produces toxins that specifically target insect larvae. It is particularly effective against caterpillars, such as the ones that can damage cannabis plants during their flowering stages. This is the most effective treatment for pests such as corn ear worm which wrecks crops across the country. Bt is considered a natural and selective pesticide, meaning it targets specific pests without harming beneficial insects or the environment.
Bt is highly regarded in organic farming due to its safety profile, and can be used until days before harvest without effecting flower quality.
3. Insecticidal Soap
Insecticidal soaps are made from potassium salts of fatty acids, and they work by breaking down the outer protective layer of insects, causing them to dehydrate and die. These soaps are effective against soft-bodied pests such as aphids, whiteflies, and thrips. They are considered safe for most plants and are often used in organic farming systems.
Insecticidal soaps are also considered a low-toxicity pesticide option for cannabis cultivation, making them a popular choice for growers who want to avoid chemical residues on their plants. However, they need to be applied carefully, as they can harm beneficial insects and certain plant varieties if overused.
4. Sulfur
Sulfur is a widely used fungicide in both conventional and organic cannabis cultivation. It is effective in controlling fungal diseases such as powdery mildew and botrytis (gray mold), which can be especially problematic in humid climates. Sulfur works by inhibiting fungal growth and disrupting the life cycle of mold spores. Many cultivators also use it to aid in fighting hemp russet mites which can be devastating. Growers often put sulfur burners in their grow rooms for occasional treatments.
Although sulfur is generally considered safe when used correctly, it can cause plant damage if applied during high temperatures or if used excessively. Growers must be cautious and follow proper application guidelines to avoid harming the plants or the environment. Never treat during flowering.
5. Spinosad
Spinosad is a natural insecticide derived from soil bacteria. It is highly effective against a range of pests, including thrips, spider mites, and leaf miners. Spinosad works by disrupting the insect's nervous system, causing paralysis and death. It is considered a low-toxicity pesticide, making it a popular choice for organic growers. That said it is not considered to be safe when tested at any levels in cannabis plants, and flower with any residual Spinosad will fail many state testing protocols. If you are growing commercially, do not use Spinosad.
One of the benefits of spinosad is that it has a relatively short residual effect, meaning it degrades quickly and leaves little to no trace on the plant. However, some studies suggest that it can be harmful to beneficial insects, such as bees, if not applied properly.
6. Neem Oil
Neem oil is a natural pesticide extracted from the seeds of the neem tree. It is a broad-spectrum insecticide that works by disrupting the feeding and reproductive processes of pests such as aphids, whiteflies, and spider mites. Neem oil also has antifungal properties, making it useful for controlling mold and mildew.
One of the advantages of neem oil is that it is organic and generally considered safe for humans and animals when used in moderation. However, it has been shown to remain on flowers after harvest, and treated flower cannot be used for any form of extractions. It is essential for growers to follow application guidelines carefully, as neem oil can be phytotoxic (harmful to plants) if applied too heavily.
7. Bioinsecticides
Among the most popular for commercial cultivators are biologicals, or bacteria and fungi treated on plants than when consumed, kill insect populations. These are not considered toxic, and therefor not tested for - but work relatively well on a wide range of pests. Treatments can be expensive and must be applied frequently. Common bacterium's and fungal species are Chromobacterium subtsugae, Burkholderia rinojensis, and Beauveria bassiana.
