Are Biocontrol Solutions a Useful Tool for Cannabis Cultivators?
Cannabis is a relatively grey area when it comes to pesticide use. Just as the legality of cannabis cultivation in the United States differs at the federal and state level, so too does the legality of pesticide use on cannabis.
At the federal level, no pesticide product is registered for use on cannabis. But at the state level, a region with an internal legal cannabis industry can produce a list of pesticides that it deems safe to use on cannabis, which cultivators can then apply to their crop.
As these lists are continually updated, this system can get even more confusing. If a company were to operate several cultivation facilities in multiple states, there is no guarantee that it would be able to use the same pesticides in every facility.
Pesticide use also carries with it additional complications, such as the possibility that their use might affect the quality of the crop or harm the local environment. Some common pesticides in agriculture have been used to such an extent that insects have become immune to their effects. Pesticide residues can also be tricky to completely remove from cannabis plant material, and even small amounts of these residues may present a health risk to consumers.
In the face of so many complications, some cannabis cultivators are turning an alternative pest control method: biological pest control.
What is biological pest control?
Biological pest control, or biocontrol, does away with the use of chemical pesticides, and with it the risks of pest immunity and chemical contamination. Instead, pest infestations are treated with other organisms – such as insects, mites, or nematodes – that prey on the harmful pests while leaving the main crop undamaged.
“Biological control in cannabis, and also in all other crops, is making sure you grow your crop in a healthy way and control your threats as and when needed, with organisms that occur in the environment,” explains Sam Gui, an integrated pest management and pollination specialist at the Belgium-based crop management firm Biobest Group NV, to Analytical Cannabis.
“It’s residue-free. So for the consumer there’s a huge benefit because if people don’t need to use chemicals, or if people can use less chemicals for growing their crops, they will not have any chemical residue in their crops, which is a health benefit for the consumer.”
By avoiding the use of pesticides, Gui says, farmers may also find that their crops grow more vigorously.
Using fewer chemical products during cultivation is also better for the environment. The harmful effects of pesticides on the environment have been well documented through decades of extensive research and numerous studies have demonstrated that selected pesticides and insecticides are capable of adversely affecting the growth and diversity of the soil microbiome, and indirectly impacting the growth of some crops.
What biocontrol solutions are out there?
As biocontrol methods rely on exploiting the natural behaviors of organisms, a crop with multiple different types of pest infestation risks will need to employ numerous different biocontrol systems.
“There are groups of pests that we will find almost in every cannabis crop,” Gui explains. “Spider mites [are] one of them. There is also a series of thrip species we will find nearly in all crops. Frankliniella occidentalis is probably the most commonly found, but we find several ones.”
“There is a very good one-to-one biocontrol, Phytoseiulus persimilis, which is a specialized predatory mite for spider mite control. 'Specialized predatory mite’ means it will eat nothing else than that particular prey. So if that particular prey – if this spider mite is not present – it will rather die than switch its ‘menu’ to anything else,” Gui says.
Despite this selective diet, it’s still possible to use biological pest control methods as a preventative strategy, similarly to how many farmers use chemical pesticides. Instead of releasing a single wave of predatory mites at once, some biological pest control systems function as miniature rearing environments that can nurture predatory mites to maturity over the course of a number of weeks.
By spreading these rearing environments throughout a crop, farmers can release steady numbers of the predatory mites over longer periods of time – effectively acting as a preventative pest management system. Other mites are more generalist and will survive on other non-pest food sources. Inoculating crops with more generalized predatory mites is also an effective preventative pest control method. More generalist mites include Amblyseius cucumeris or Amblyseius swirskii, which are used for tackling thrips species.
Exactly which biocontrol solutions are most suitable for a cannabis cultivator will vary greatly from facility to facility; different cultivation environments can have different common pest risks, different environmental factors, and different cultivation practices.
“For cannabis, just like most other crops we make strategies for, it is very important for us to tailor a program. That is who Biobest is,” Gui says. “There is a roadmap of a program you would expect to follow, but this program is tailored to each grower. No two cannabis growers are going to get an identical pest management program from us."
