I’ve seen quite a few sources that say cannabis plants are rarely attacked by pests and plant diseases. People even say that they are “easy” to grow using organic methods, but the facts outweigh these opinions. Pesticides and fungicides are routinely found in medical cannabis, a situation that could make sick people even sicker. Most ironic of all, a lot of pesticides and fungicides are actually carcinogenic.
What are the pests and diseases that people spray?
No grower in his or her right mind is going to spray pesticides unless they have to. After all, pesticides cost money, and one doesn’t do work just for work’s sake. But when your crop is being threatened, you take the next step, and quite often, the easiest solution is toxic pesticides.
Spider mites are among the most dreaded pests to attack cannabis. They’re very hard to control, because what kills the adults doesn’t kill the eggs and vise versa. The life cycle is very rapid, and effective control could mean spraying every second or third day for a few weeks.
Growers know their plants are being affected when they see white stipple markings on the leaves. The mites themselves are difficult to spot with the naked eye, but they make fine webs on the undersides of leaves, and if you look closely, you might be able to see the tiny mites, like specks of dust on the undersides of foliage.
There are several organic approaches to controlling spider mite, but using predatory mites is a good solution. That means there will always be some spider mites and some predators, with numbers see-sawing. When the predators munch enough of the mites, there isn’t enough food for them, so numbers dwindle. Now the spider mites begin to breed again, but the predatory mites notice there is more food, and begin to breed too. Predatory mites look similar to spider mites, but are a little larger and much faster and more active.
There are two problems with aphids: Firstly, they suck sap out of the plant, reducing its vigour. Secondly, and more damagingly, they excrete a sugary substance that turns into a black mould called sooty mould. It can’t be rinsed off, and turns everything into sticky mess.
Aphids can also be controlled with predators such as lady-bugs, but there are several natural oils that will suffocate them if spray coverage is good enough. Once the plant begins to flower, the oils might not be suitable, but organic insecticidal soaps can be used.
Once again, good coverage is important, and since aphids tend to hide away, many people opt for systemic pesticides that enter the plant’s sap, killing the pests from the inside out. That’s fine if you aren’t planning to eat the crop, but the pesticide residues aren’t good if you plan to eat it, and especially not if you are going to make a concentrated extract.
By now, you’re starting to realize that insect love cannabis, and caterpillars are no exception. One particular type hides away in the buds, eating them from the inside out! As usual, there are organic control methods, but they are more difficult than chemical ones. One of these is Baciliis thuringensis (BT), a common bacterium that doesn’t affect people but does kill off insects. However, some believe that BT can cause inflammation in humans, so it’s not the best solution for a medicinal crop.
Again, insecticidal soaps and oils will work if coverage is good enough, and natural pyrethrum, which breaks down completely within 24 hours offers an additional option.
Fungi are particularly fond of the buds during wet weather and after harvest. A lot of the residues that are picked up in cannabis come from chemicals applied post-harvest to control these moulds. The moulds themselves also create mycotoxins or fungal toxins.
The answers here are trickier. Cultural control, in other words, growing the plant in such a way that it doesn’t get infected in the first place, and taking care that material isn’t overcrowded after harvest is the best solution.
Growing organic cannabis isn’t as easy as you might think!
Growing cannabis organically isn’t all that easy. If your fields have been cultivated using organic practices for years, there’s a good chance that natural predators will deal with pests, and if conditions are favourable, fungal infections are less common.
Organically grown cannabis is a valuable crop that will provide many health benefits, but pesticides and fungicides can ruin this. That’s why we’re so careful about the material we choose to make our cannabis products.
Author: Andrea Durrheim