All cannabis growers will face pest challenges at some point. This is true no matter where the crop, what region, outside in the elements, or inside, under cover. The type of pest may be somewhat different by region, but more or less the same suite of controls are available to the grower. Some growers may opt for synthetic, chemically derived pesticides which will likely work fast and take care of the problem. But, there are a host of reasons why cannabis cultivators should opt for naturally derived pesticide solutions.
All-natural pesticide solutions and those derived from natural sources are often just as effective as synthetic ones. They may take longer to deliver their effect and can be more expensive than synthetics, but most conscientious cannabis growers would agree the additional sunk costs will pay dividends that make it worthwhile. Cannabis treated with natural pesticides does not have chemical residue which can then be consumed by the end user. Naturally-derived solutions are usually (not always) less harmful for the user and applicator as well in the case of accidental exposure. Pests treated with some form of all-natural pesticide are also far less likely, or even unable in most cases, to develop any sort of resistance to the treatment that they can then pass down to subsequent generations. This is one of the main reasons why synthetic pesticides lose efficacy over a short period of time when used repeatedly to control a pest situation.
Another reason for all-natural pesticides is to pursue or maintain organic certification status. While this is a practice not officially recognized widely yet, it is slowly starting to happen in states and regions where cannabis can be legally grown. Many health-conscious consumers want to know that the same level of care goes into the growing of their cannabis as goes into their locally-grown vegetables found at farmer’s markets. It should be noted there is no legal definition of “all-natural” and all-natural does not mean it is automatically appropriate or safe to use as a pesticide.
The following sections cover naturally derived sources of several types of pesticides and will be useful in identifying which available pesticides are indeed “all-natural.”
Botanically Derived Pesticides
Many plants themselves, through evolution or happenstance, produce compounds, oils, or other substances with the ability to repel or kill insects. Many products have been manufactured that make good use of these substances to recreate their stopping power on crops that don’t have the ability to generate their own pesticides.
Pyrethrin — Pyrethrin(s) is a naturally occurring, insect-killing compound found in a species of Chrysanthemum found in Africa. It is so effective as a pesticide that there are synthetic compounds, called pyrethroids, that have been created to kill pests using the same modes of action. It should be noted that while pyrethrin is organic, pyrethroids are not.
Neem — The neem tree in India has been known for centuries as a source for controlling insect pests. The oil from the tree is used around the world as an insecticide, an insect repellant, and it even has some antifungal properties as well, making it a dual-purpose pesticide.
Herb oils — Dozens of fragrant plants, most commonly herbs, comprise the main constituency of many all-natural insect repellants. Pesticides containing the oils of plants such as rosemary, lavender, and mint are often used preventatively on cannabis to keep several species of pests at bay. The same principle exists for repellant products containing capsaicin (the compound in hot peppers that makes them spicy) to keep larger animals such as deer and rabbits from eating other outdoor crops.
Sugar/molasses — Pesticides are sometimes formulated with various sugars. The intent with these sweet and heavy mixes is to kill pests by smothering them. This is not a preventative product but can be used effectively as an all-natural insecticide if the pest outbreak is caught soon enough and is relatively small.
Plants are not the only source of raw materials for all-natural pesticides. Living organisms from the microscopic to the ancient can be used as pesticides on cannabis.
Diatomaceous earth — Diatomaceous earth (DE) has several applications but is commonly used as a pesticide for both treatment and prevention on cannabis crops. It is most effective on insects and pests with moist bodies as it is intended to control some pests as a desiccant, causing them to dry up and die. Because the source of DE is ground, fossilized organisms, there are many rough edges on the individual grains of DE. A sprinkle around plants prone to attack from slithering pests such as snails and slugs can also be performed as it will cut open any such pest that crawls over diatomaceous earth, often resulting in death to the pest.
Bt — On the other end of the spectrum is an all-natural pesticide that is very much still alive. Bacillis thurengiensis, or Bt, is bacteria that is harmless to humans, but lethal to the larval stage (caterpillar phase) of many pests. In many cases, the larval stage is the most damaging to plants as the larvae must consume copious amounts of foliage to store enough energy to pupate. Because it’s alive, Bt applications should be used very soon after purchase. The longer it sits on a shelf unused, the less effective that particular bottle or dose becomes.
Beneficial Insects For Cannabis
In nature, almost every single creature can fall prey to another. In horticulture, this isn’t always true, especially in greenhouse environments or other indoor or tented setups. Pest species arrive and their population grows exponentially because there is not a natural predator population. An all-natural solution is to release beneficial insects to predate or parasitize the pests. Some beneficial insects work by directly consuming pest species (predation); other do their job by injecting their eggs directly into the living bodies of pests. Their eggs then hatch inside their host and feed off of the pest until they emerge as larvae, having killed the pest (parasitism). There are dozens, if not hundreds, of species available but a few of the more common ones follow:
Nematodes — Nematodes are a microscopic worm species (there are many) that play the part of both predator and parasite. They live in the soil and feed on the larvae of other soil dwelling pests and also lay their eggs inside soil dwelling pests. There are beneficial and harmful nematodes. The beneficial species are commercially available as an all-natural pesticide.
Ladybugs — Ladybugs will eat just about any soft-bodied pest, but especially love to munch on aphids. Their offspring, ladybug larvae, have an insatiable appetite for aphids and other pests that puts their parents’ output to shame.
Aphidoletes — Aphidoletes are a predatory wasp species that also seek out aphids. They use them as hosts for their developing eggs, not as a food source for the adults. They inject their eggs into unsuspecting aphids which then are fed on from within until their young emerge from a hole they create in the aphid’s carcass. These parasitized aphids that they leave in their wake are known as aphid mummies and are easily identifiable by the exit hole left behind by the wasp. Several other parasitic wasps exist as well, seeking a wide range of pest hosts.
Predatory mites — Mites (like spider mites) can be a tough pest to remove from cannabis, especially if an all-natural solution is sought. They are not true insects, and as such are not always susceptible to insecticides, regardless of their formulation. One of the more effective solutions are beneficial mites. These predators will seek out and consume the plant-damaging spider mites that can harm your crop. There are several types of predatory mites. The kind you use will be dependent on the pest species you are dealing with.
There are a lot of products out there with various claims to their ingredients’ origins. Do not pay as much attention to the product name as much as the active ingredients. These will tell you if you are indeed in possession of an all-natural pest solution. If unsure if a product is suitable for pest control and is naturally derived, check with the professionals at your local cooperative extension, local garden, or hydroponic stores, or by performing your own research online. Any product that has been approved for use on organic crops in the US, must be certified by the Organic Materials Review Institute (OMRI).