Plant Pest Series: Fungus Gnats
An adult fungus gnat. Image courtesy of Planet Natural Research Center.
This month, we are featuring a series of articles that will teach you how to prevent, detect and eradicate common houseplant pests. Up this week: FUNGUS GNATS
Prevention
Fungus gnats thrive in moist, warm soil. Fungus gnats also spread very quickly, so it’s important to quarantine any plant(s) you suspect may have an infestation as soon as possible. This will help keep it from spreading to your other plants.
Correct watering and air circulation is the best way to prevent fungus gnats. Keeping your plants clean and free of debris is also key. As you do your watering routine, check your plants for abnormalities and/or bugs and remove any dead foliage. Learn more plant housekeeping tips here.
Fungus gnat larvae thrive in consistently damp soil and humidity trays. Image courtesy of University of Nebraska.
Detection
Fortunately, fungus gnats are usually easy to spot. Unfortunately, they are one of the most annoying of all houseplant pests. The small, black, adult insects that fly around the plant (similar to fruit flies) are actually harmless. However, they lay their eggs in the damp soil and the maggots the eggs produce can be harmful to your plants. The maggots normally feed on organic matter in the soil but they will occasionally devour young roots.
Eradication
Water with hydrogen peroxide.
Hydrogen peroxide helps encourage healthy roots because of its extra oxygen molecule. This extra bit of oxygen better enables the roots to absorb more nutrients, which means faster, healthier, and more vigorous growth. And as a bonus, hydrogen peroxide can help discourage unwanted bacteria/fungi/bugs that may be lurking in the soil. To give plants an added boost of oxygen for pest control using the 3% solution, add 1 teaspoon per cup of water in a spray bottle or watering can and apply to plant.
Use neem oil.
Neem oil is an organic oil derived from the neem tree. Use according to label instructions.
Try beneficial nematodes.
Beneficial nematodes are microscopic insects that seek out and destroy over 230 kinds of soil dwelling and wood boring insects but will not affect humans, animals, or plants. This method is particularly useful for severe infestations. Be sure to follow the directions on the packaging. Get yours here.
Repot as a last resort.
If all else fails on your eradication front, you can repot your affected plants. Follow our guide to repotting, and be sure to use fresh soil and a clean pot with adequate drainage.