The cannabis industry has exploded since many states have legalized it partially or fully. Whether growing commercially or privately, you might have discovered how difficult it can be to maintain quality control compared to other plants.
Beyond the need for proper lighting, feeding, and environmental conditions like transplant shock, cannabis is prone to pest infestations, especially spider mites.
These pests can wreak havoc on your crop if not dealt with swiftly, but just how do you eliminate them without further damaging these plants?
The Problem Of Spider Mites
Spider mites are tiny arachnids that feed on the sap of various plants. Often the first sign of a spider mite infestation is the presence of messy webbing between leaves – an ability that led to their name.
Spider mites use these webs to travel between leaves and for protection. It’s usually only when an infestation becomes out of control that you notice any additional signs.
Due to their tiny size, spider mites look like little specks on the underside of your plant’s leaves.
When they infest a leaf, they’ll pierce it and feed upon the sap.
This can eventually lead to yellow or brown spots on the top surface of the leaves as they dehydrate the plant and cause a loss of chlorophyll.
But there are two other reasons to fear a spider mite infestation.
First, a single female can produce hundreds of eggs, quickly producing more spider mites that continue the cycle.
Thus you could face a massive population explosion in just a couple of months.
Even worse, the eggs are often shielded from pesticides, and adults can quickly become resistant to pesticides if they use the same product too often.
This means you can seemingly eliminate an infestation only to have it spring back as the new eggs hatch, bearing superbugs.
How To Get Rid Of Spider Mites On Weed
Getting rid of spider mites isn’t as difficult as it first seems, but only if you deal with them quickly.
Here’s what you need to know to keep your cannabis crop safe.
Chemical vs. Organic Methods
As we mentioned already, chemical pesticides can be risky business.
If you intend to use a chemical method, get different products with different active ingredients specified for use on spider mites.
Alternate between the different products to reduce the risk of the spider mites becoming resistant.
Follow all instructions carefully and do at least one treatment after the infestation appears to be gone to catch any hatching eggs.
You will also need to remember that pesticides are toxic, so you must take extra steps to ensure the cannabis is safe for consumption.
Organic methods are a completely different matter.
Spider mites are unable to build resistance to natural methods.
However, these methods take longer to produce results, so they might not be able to handle a severe infestation fast enough to prevent major crop damage.
In such extreme cases, it might be necessary to use a chemical option, then follow up with natural remedies.
The following methods are highly effective and can be used together for added impact.
Even better, these two methods can be used as a preventative without having any negative effects on your plants, unlike some other natural options out there.
Alcohol
Isopropyl alcohol (and rubbing alcohol, for that matter) can kill spider mites on contact.
The general suggestion is to mix 1 part alcohol with 9 parts water and place in a spray bottle or mister.
However, simply spraying the plants will only kill those spider mites that get hit by the spray. We suggest taking a very soft cloth (such as microfiber) and gently wiping the leaves after spraying to ensure you get all the spider mites.
This method shouldn’t harm your cannabis and can help bring an infestation under control, although it can be difficult to get every last spider mite using this method alone.
Natural Predators
Mother Nature doesn’t create a pest without providing a predator to keep the population under control.
Ladybugs are not only cute but also have a voracious appetite, and spider mites are one of the many foods they absolutely love.
When working in a greenhouse or enclosed space, it’s easy to keep a ladybug population, although you’ll need to add plants the ladybugs are attracted to if you plan on using them in an open-air environment.
Another effective predator is actually another kind of mite – predator mites, to be precise.
These mites are also tiny, but they won’t harm your plants. Instead, they’ll patrol the leaves looking for spider mites and other pests to munch on.
Both ladybugs and predator mites can be ordered online, and keeping a population of both will drastically reduce the risk of pest problems.
Neem Oil
WARNING: While neem oil is a very effective method, you should avoid using it when your cannabis is flowering, as it may alter the flavor of the buds.
Neem oil is a natural plant extract that kills hundreds of different pests, including spider mites.
When the clarified neem oil is used as a foliar spray, it can kill on contact, although it has the same drawback as alcohol sprays.
The good news is that it dissipates without leaving behind a residue in about an hour, so you can treat your plants at dusk or dawn with minimal risk to beneficial insects.
Meanwhile, pure neem oil can be made into a soil soak that kills more slowly but will only harm pests that chew or pierce the treated plant.
In this form, the oil mimics the natural hormones of the target, causing nymphs to be unable to reach adulthood, leaving bugs sterile, and can even make them think they’re full – causing them to starve to death.
Foliar sprays need to be applied every other day for 14 days or until the infestation is completely gone and can be used every two weeks as a preventative.
Meanwhile, soil soaks last up to 22 days and can be applied every 3 weeks as a preventative.
Again, please remember to only use neem oil after harvesting the buds or before the buds begin to form if you don’t want to risk the buds smelling or tasting off.
A good rule of thumb is to stop using neem products 3 weeks before your estimated harvest time so there are no residual traces in or on the plant by the time you’re ready to remove the buds.