Fungus gnats are one of the more annoying pests you may potentially encounter when growing cannabis. While these small black flies are harmless to people, they can prove to be quite lethal to your cannabis crop if left unchecked.
Fungus gnats are small flies that pretty much live for the sole purpose of reproducing. While adult flies are harmless to humans since they don’t bite or spread human pathogens, they can be a big problem for your plants.
Adult fungus gnats can be vectors for plant diseases like Botrytis, Fusarium, and Pythium. But even worse for your plants are the larvae of fungus gnats which can kill or stunt the growth of seedlings and young plants as well as severely weaken a more mature cannabis plant by feeding on roots, root hairs, and the organic matter in your growing medium.
If you start noticing fungus gnats around your plants, it’s almost a surefire indicator that you’ve been overwatering your plants.
A few indicators that can signal that you have a fungus gnat infestation:
Still unsure whether you’re dealing with a shit ton of fungus gnats? You can try the following:
If you want to get rid of fungus gnats and minimize your chances of having to deal with a future infestation then you’ll want to take measures to kill the current fungus gnat population as well as take steps for prevention.
To kill your fungus gnat population, you’ll want to take a two-prong approach that deals with both the adults as well as the larvae.
Yellow sticky traps are a great first step in helping to control the problem. The gnats are attracted to the yellow color allowing you to easily capture the flying mature ones that will end up stuck to the trap.
I would suggest having at least one trap for each plant. Even though fungus gnats don’t typically fly very far, they can still easily end up in a neighboring plant.
There are several products that you can try to make use of to help with reducing and eventually killing off the larvae. As far as research shows, these products are nontoxic to people.
The best way to avoid a fungus gnat problem is to ensure that you don’t provide a hospitable environment for them in the first place. As we mentioned earlier, fungus gnats are attracted to moist soil near the surface so let your soil dry between watering as much as your plants will tolerate. Furthermore, look to bottom-water your plants as this will make it easier to keep your surface layer dry.