Fungus Gnats, what a pest!
If I ever had to choose a pest in the garden it certainly would not be fungus gnats. When you see the first gnat flying around you already have a problem. I remember when I saw the first few flying around and I thought to myself, just a couple little gnats, not too intimidating I can take care of that easily. At that point I thought they were just harmless little gnats. And that’s when I unintentionally let the problem get out of control.
At first I hung a few fly tapes believing that would be a sufficient solution. It wasn’t, and therein lays the problem. You see when fungus gnats arrive and you see them for the first time, they have already hatched their larva in the soil and the larva is an even bigger problem than the gnat itself. The larva feed from the roots of the plant consuming the nutrients that would be used by the plant for growth and development and the gnats feed by poking holes in the leaves and drinking from them.
Once I learned how devastating these larva and gnats can become I went to work on the problem. I purchased an OMRI listed bug spray and doused the plants. No change. A friend told me that predatory nematodes would take care of the issues so I purchased a million of those but that didn’t work either. I thought maybe I could just flood the root system with CO2, I took the plants from their pots placed them in a bag and tied it tight then filled it with co2. I thought I had something that time but to no avail.
After all these attempts I discovered a two part solution that worked extremely well and finally solved the problem.
The larva that resides in the soil seem nearly impossible to control, but when I finally found the answer it was not only affordable but simply and effective. Hydrogen peroxide is the answer.
Here’s how to use Hydrogen peroxide to completely rid the soil of Fungus gnat larva.
First allow the soil to dry out somewhat thoroughly, not entirely. The larva reside in the top two and bottom two inches of the pot.
Mix one part 3% hydrogen peroxide to three parts water.
I filled the sink with about two inches of solution to cover the drain holes at the bottom of the pot then set the potted plant in the solution. The solution will be drawn in via the holes in the pot, at the same time water the plant with the remaining solution making sure that the top two inches of soil are completely saturated. The soil will begin to fizz and bubble just like when place peroxide on a cut. Don’t worry because the plant doesn’t mind at all. Hydrogen peroxide breaks down to oxygen and water both of which the plant enjoys, meanwhile the larva are destroyed on contact. This process also aerates the soil. You will find that the soil has actually risen in the pot due to the added air in the soil.
The fungus gnat larva is now gone, gone, gone! I follow this up about an hour later with a fresh water and nutrient solution which will resettle to soil back to its original depth and offer much needed nutrients to the plant.
As I mentioned this is a two part solution to the fungus gnat problem. While researching on the web I found a product called “AzaMax” by General Hydroponics. The product is a derivative of the neem seed but it is not neem oil. AzaMax does not kill on contact but instead alters their ability to feed on the plant’s leaves while at the same time inhibits them from reproducing. Due to these actions the gnat population soon dies off leaving your plant free to grow and thrive.
Congratulations you have now successfully rid your plants of the fungus gnat infestation.