What Are Fungus Gnats & How to Kill Them?

What Are Fungus Gnats & How To Kill Them? – WeedSeedShop

Most gardeners are familiar with fungus gnats and these little pests really love to feast on indoor cannabis plants. They can cause havoc in your root system and your final harvest. The good news is getting rid of them is relatively quick and easy. To learn how to deal with a gnat problem, keep reading

The fungus gnat is one of the most annoying pests in your cannabis garden. In fact, these little things can cause huge problems for your indoor plants, whether the gnats are larval or adults. If fungus gnats are left to feast on your plant and soil for too long, then you risk losing your plant to a whole bunch of fungal diseases.

The best way to deal with this is to try and get them early! This article is all about how to identify if you have a gnat problem and how to attack it efficiently.

What Are Fungus Gnats & How To Kill Them? – WeedSeedShop

What are fungus gnats?

Fungus gnats are known scientifically as Mycetophilidae or Sciaridae. They are tiny little insects that are almost invisible to the naked eye. These little guys love to feast on fungi (hence their name), which means they are particularly attracted to indoor plants, especially when the moisture is high. They live at the soil base and feast on fungi in the soil.

Fungus gnats can lay up to 200 eggs per week at the base of your cannabis plants, meaning that things can get ugly very quickly. Dealing with them is a two-stage process, because you have to attack both the larvae and the adults.

How fungus gnats affect your plants

Firstly, fungus gnats attack the soil of your plant by leaving droppings and laying eggs in there. This creates a drainage problem in the soil, which weed doesn’t deal with very well. As a result, the soil becomes vulnerable to fungal diseases. Once they have finished eating all of the fungus in the soil, they begin eating the root system of your plant. This can lead to stunted growth, discolouration of the leaves and can destroy the stems and branches of your plants.

Ultimately, if you realize you have fungus gnats, you have to take action immediately or your final harvest could be compromised.

What Are Fungus Gnats & How To Kill Them? – WeedSeedShop

Checking for fungus gnats

To check for fungus gnats, purchase some yellow sticky cards. You can buy them at most gardening stores because gardeners know that gnats love the colour yellow. If you have a gnat problem, there will be more than a few gnats on the sticky cards after leaving them in the soil for a couple of days.

To see if the gnats have been leaving larvae in your soil, cut an inch-thick piece of raw potato. Put it inside your soil and take it out after eight hours. You know there are gnat eggs everywhere if there are maggots feasting on your potato.

Dealing with them

So you’ve identified that there are some nasty gnats feasting on the soil of your cannabis and you need to get rid of them. The good news is that getting rid of the adults is easy. Those yellow sticky cards you used to check for gnats can be stuck around the soil, pots and outside of your plants. They will stick to the yellow cards and die.

Larval gnats can be poisoned with hydrogen peroxide, and that is the only way to really handle them. First you should delay your watering cycle for a few days to let the soil get really dry on the top. Using one part of 3% hydrogen peroxide and four parts water, really give your top layer of soil a soaking. Distributing the mix thoroughly over the top layer of soil will make sure all the larvae die.

Don’t panic, this won’t have any negative consequences for your plants, and you can even use this as a preventative measure to make sure the gnats don’t come back in the future!


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  • Author_profiles-WSS-Sera Jane Ghaly

    Sera Jane Ghaly

    I like to call myself the traveling gypsy wanderer of the world. Born in Melbourne Australia, but reborn just about everywhere else in the world. I have a healthy obsession with words and languages, using them as a vehicle to navigate this multi-dimensional human experience. My enthusiasm for marijuana started in the USA, and since then I’ve been traveling the world with the herb as my inspiration. Sweet Mary Jane has led me to shamanic ceremonies in the Amazon all the way to smoking ganja with the Babas in India.
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