If you just want to know what I used to kill fungus gnats successfully, and don’t need my whole long winded spiel on use case and situation, here you go! Captain Jacks Dead Bug Brew, by Bonide and Fungicide 3 by Garden Safe.
I had a recent outbreak of fungus gnats, beyond anything I’d ever seen before. My best guess is that a big box store ‘living Christmas tree’ brought them home in the soil. My dormant figs that were sitting in the corner of the living room became inundated with them.
Look at this evil bastard, as he awaits his fate.
Although I’ve never seen fungus gnats do anything extremely detrimental to a plant, perhaps I’ve just never let it get that far, they are a disgusting and incredibly annoying inside a household.
I’ve read and tried all the hippy dippy home remedy approaches to the problem. Use of a potato, a sand topsoil topping, apple-cider vinegar traps, etc. None of them work like a specific and liberal attack with organic plant safe bug spray, fungicide, and sticky traps.
What I used to get rid of them was a direct application of organic Spinosad spray, Captain Jacks Dead Bug Brew, by Bonide, to the surfaces of the pots. I made sure to scrape away the top surface of the soil and give a thorough spray to the soil as well. I paid particular attention to drainage holes.
This causes fungus gnats to die and flee. When they flee they are attracted to sticky traps, which are only good for catching adults, but aids in controlling the problem.
These two measures work directly on the adult and larval fungus gnats, but does not control the source of the problem, fungus growing in the soil. Fungus growing in the soil is what feeds the fungus gnat larvae. Maybe a bloom on one plant caused spores to spread like wildfire. Over-watering or warm temperatures could also have exacerbated the problem, which is something to be mindful of in the future. Regardless of why or how it happened, it needed to be controlled with a fungicide.
I used an organic Neem oil based 3 in 1 fungicide, insecticide, miticide spray, Fungicide 3 by Garden Safe. Its also highly effective on contact, and controls other issues, like Powdery Mildew, Black Spot, Rust, Spider Mites, Aphids, Whiteflies.
There is no question the combination of Spinosad, Neem Oil, and sticky traps gets the job done. Its also a completely organic solution, and in experience, these treatments don’t have negative or adverse effects on plant health.