How to Get Rid of Fungus Gnats on Tomato Plants

How to Get Rid of Fungus Gnats on Tomato Plants

Have you ham-handedly tried to get rid of gnats on tomato plants without success? I got you covered. Fungus gnats cause many threats to tomato plants that can be a stumbling block to your tomato farming. Thankfully, here’s how to get rid of fungus gnats on tomato plants.

Avoid gnats on your tomato plants by setting up simple traps in your garden. Also, apply biological control methods to keep gnats off your tomatoes naturally. Better still, ensure there are no larvae on the seedlings when transplanting to prevent gnats from attacking your tomatoes.

Getting rid of fungus gnats in your tomato garden is not rocket science. This article shows you easy tricks to control and prevent fungus gnats in tomatoes.

How to Get Rid of Fungus Gnats on Tomato Plants

Setting up fungus gnats is an essential way of getting rid of fungus gnats on all tomato plants in your garden. 

First, purchase a local cider vinegar or any other soft beer and follow the following steps. 

  1. Fill a shallow container, for example, a bottle lid, with 5 drops of apple cider vinegar. You can also add a scoop of protein shake before adding the cider vinegar to attract the fungus gnats.
  2. Add 3 drops of peppermint oil and a similar amount of dish soap.
  3. Stir the liquid using a spatula and leave the mixture out beside your tomato plants.
  4. Keenly observe the fungus gnats’ activity in the trap solution.
  5. Replace the trap solution after three days to ensure that all the gnats are trapped.

The trap method is best used for killing adult fungus gnats. Therefore, it prevents them from laying more eggs and multiplying.

However, some untrapped adult and larvae gnats may remain on the plants.  That calls us to explore other methods to prevent and control fungus gnats.

How Do I Keep Gnats off my Tomatoes?

To keep gnats off your tomatoes, you must destroy them both in the adult and larvae stages. That’s because gnats have a very short lifecycle (2 weeks). Also, one fungus gnat reproduces up to 300 eggs making it easy for them to multiply and infest your tomato garden quickly. 

To destroy fungus gnats larvae, you can use neem oil and pyrethrin spray on tomato plants.

Neem oil is a cheap solution to kill adult gnats larvae. First, dilute it in the manufacturer’s ratio and drench it near the base of the plant. Then spray the oil on the tomato plant to destroy the adult gnats on the leaves and the stems.

Neem oil is safe for both indoor and outdoor tomato gardens. It’s also great for greenhouses as well as hydroponic use.

So spray a thin mist of pyrethrin spray lightly on your tomato plants and in the soil around the base of your tomatoes. If the larvae are highly concentrated in the soil, spray larger amounts of pyrethrin into the ground directly. The critical thing here is to avoid overwatering your soil even when applying these compounds to the soil.

Then, ensure that the soil dries to a depth of two inches after applying the spray. Finally, spray the pyrethrin again after four weeks to ensure the insects are no more. Also, you can use neem oil and pyrethrin spray interchangeably to avoid the fungus gnats mutation that can make it difficult to eliminate them.

How Do You Control Fungus Gnats on Tomatoes?

You can control fungus gnats on tomatoes by ensuring that you don’t transfer them from external sources into your garden. That’s by scrutinizing the seedlings for any fungus gnats larvae before transplanting them into your garden. 

So, you can change the potting mix or spray the old potting mix with pyrethrin spray. That prevents you from bringing fungus gnats, larvae, and eggs into your garden.

To the tomatoes in the garden, ensure that you don’t overwater them. Too much water in the soil causes decay and rot, creating a breeding space for fungus gnats. That makes it difficult to control them.

If you do indoor or greenhouse tomato farming, seal all the crevices or cracks on the walls and doors. Also, dispose of old garbage from the sheds to prevent the gnats from finding their way into the greenhouse.

How Do You Get Rid of Fungus Gnats Naturally?

To avoid fungus gnats naturally, you can try some biological methods. A form of bacteria called Bacillus thuringiensis var. Israelensis helps kill all fungus gnats in a short time. Although it’s not available in many spray types, you can find them in commercial products, such as fertilizers.

Another way of applying the bacteria in the soil is by spreading mosquito dunks and bits on the surface, then leaching them into the ground by watering them. You can use the bacteria both indoors and outdoors.

These mosquito dunks and bits can also be effective for killing other larvae types in the soil. As they decompose, they release the Bacillus thuringiensis var. Israelensis bacteria into the ground. 

However, you can’t use mosquito dunks to kill fungus gnats instantly since they are large and take longer to decompose.

Some nematode species also play a part in fungus gnat larvae eradication. These microorganisms control soil gnats and other thousands of soil-dwelling pests. Mix the nematodes with water for easier spreading if your tomato garden is enormous. 

Note that these beneficial nematodes and bacteria can’t be applied simultaneously with hydrogen peroxide or other compounds that can kill them. If you, therefore, use hydrogen peroxide in your soil, wait a couple of weeks before adding nematodes and bacteria. 

Also, if your tomato garden is outdoors, avoid applying nematodes at too high temperatures as they can kill them before accomplishing their purpose.

How to Prevent Fungus Gnats From Attacking my Tomato plants

You can prevent fungus gnats from attacking your tomato plants by using cinnamon. As a natural fungicide, cinnamon destroys the fungus that the gnats larvae feed on, making it difficult for them to survive. Fortunately, it also creates an inhospitable environment for the fungus, keeping them away from your tomato garden.

Sprinkle a uniform layer of cinnamon on your soil two times a week. Cinnamon is a chemical-free method of eradicating fungus gnats, and it leaves behind a pleasant smell in your garden.

Does Hydrogen Peroxide Get Rid of Fungus Gnats?

Yes, hydrogen peroxide kills all fungus gnats, larvae, eggs, adults, and pupae. Hydrogen peroxide is a good option when eradicating fungus gnats since it’s easy to work with, readily available, and doesn’t harm your plants.

Even so, ensure you use moderately concentrated hydrogen peroxide in your garden, not concentrated industrial one! You can dilute the hydrogen peroxide in a ratio of 4:1 before leaching it into the soil—for example, 1 glass of hydrogen peroxide to 4 glasses of water.

Before applying the solution, ensure that the soil is dry. Then spray the solution on the soil’s surface and ensure it reaches a few inches down. The deeper it soaks, the more effective it is. Also, you can wash the whole tomato plant in hydrogen peroxide to eradicate the fungus gnats on the leaves.

Although it fizzes and foams, don’t worry since it’s not harmful to the plants. That’s because it breaks down into water and hydrogen molecules that are harmless to plants.

What Else Can I Spray on My Plants to Get Rid of Gnats?

If these tiny insects are still invading your tomato plants, spray a soap solution on them to get rid of the remaining fungus gnats.

Put a few drops of liquid Castile soap or liquid dish soap in a water-full cup and shake the mixture to ensure the soap dissolves. Put the solution in a spray bottle and spray it on the soil containing larvae or over the tomato plant. Respray the solution after five days to ensure that all the gnats are dead.

Even though some people prefer using vinegar traps and other methods, spraying soap solution is better and more effective for killing both adults 1and  larvae. However, vinegar traps are better for killing adult fungus gnats.


What Is the Best Gnat Killer?

When choosing the best gnat killer, we consider their price, effectiveness, and safety. Therefore, the best gnat killers are effective, affordable, and discreet.  

Other than homemade gnat killers, some commercial gnat killers such as Fenun fly traps, Faicuk 20-Pack Dual-Sided Yellow Sticky Traps, and Katchy Indoor Fly Trap stand out.

Can Tomato Plants Recover From Fungus Gnats?

Yes, tomato plants can recover from gnats infestation. But if you’ve planted your tomatoes in kitchen pots, isolate the infected plants from the rest to avoid spreading the gnats.

Then, give the plants tender care to regain their health. Finally, remember to put the control measures we’ve illustrated above to ensure they are gnat free.

Bottom Line

Having fungus gnats in your tomato garden can make your tomato plant grow in an unhealthy manner or even cause death. The fungus gnats lay eggs that hatch into larvae, creating havoc on your emerging tomatoes and tomato seedlings.

Thankfully, this article covers some brilliant ways to cut them off, such as applying vinegar traps, pyrethrin sprays, and neem oil. These methods will help you eliminate fungus gnats at all stages of their lifecycle.

I hope these tips will help you and your tomato plants thrive happily, healthy, and pest-free.