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LEDWisdom Pest Management Articles #2 Fungus Gnats

Updated: Jun 27

As LEDWisdom, we continue our plant pests article series with fungal gnats. Fungus gnats are dark-colored, short-lived mosquitoes that look like small fruit flies. If your plants are infested, if you look carefully, you can see mosquitoes swarming the soil surface. Mosquito fungi, unlike some other pests, live in the soil and do not care much for the leaves or flowers of your plants. Instead, the fungus gnat larvae, which emerge from the eggs they place under the ground, feed on the roots of your plant and damage them in order to become adults. Because the root system is critical for healthy growth, a fungus gnat infestation can have devastating consequences. As LEDWisdom, we will share many solutions for you to get rid of fungus gnats in this article.


Fungus gnats are almost always an indication of damp conditions in your grow room and often appear when plants are overwatered. The problem may become permanent, as they are difficult to notice after they appear.


Fungus gnats go through four phases during their development; egg, larva, pupa and adult. In suitable warm and humid conditions, adult females lay hundreds of eggs in the soil. The larvae feed for about two weeks and then pupate near the soil surface. After 3-7 days in the pupal stage, adult gnats emerge and live for about eight days. Adult gnats take about 3-4 weeks to develop from eggs. So even if you get rid of the problem, you need to make sure you don't see mosquitoes for the next 3-4 weeks.


Because fungal spores are almost always in our environment, all the conditions gnats need to reproduce are water and organic matter. If plant growth media purchased at home and garden stores are not properly sterilized or stored properly, they may contain fungus gnats eggs.


Fungus gnats' favorite food is not the roots of your plants. They prefer to eat primarily fungal masses and decaying matter formed in the soil. However, when the organic matter in the soil is depleted, they start to cause problems for your plants. In this case, fungus mosquito larvae eat and damage root hairs and sensitive plant roots.


The fertilizers we use while feeding our plants can be organic and since we will apply these fertilizers continuously, the fungus gnat larvae may not harm the roots of your plants. However, if the problem is not intervened, the number of gnats and thus their larvae will increase significantly, and permanent and major damage may occur to your plant.


When roots are damaged during a fungus gnat infestation, plants may show various signs of disease, including yellow leaves, wilting, spotting and drooping. Symptoms of nutrient deficiencies (sick growth, leaf discoloration, etc.) may occur despite the correct pH and appropriate nutrients. Seedlings weaken, topple, wither or die. Slowed growth and low yield are observed.


A fungus gnat infestation is relatively easy to diagnose. They are very small, but you can see them if you get close enough to your plants. We can list several methods for diagnosing this infestation;


• Observing for tiny flies crawling or jumping in the soil around your plants.


• To check the white maggots, which are not easy to notice because they are very small and may be hidden in the soil, with the help of a lens.


• Numerous other unexplained symptoms, including pale leaves, spots, brown edges on leaves and drooping, can lead to incorrect intervention as these may indicate gnats and these symptoms may manifest as they do in other plant problems and diseases. For this reason, taking all necessary precautions before an infestation occurs is the most effective method to prevent infestation.


To approach the subject from another angle, fungus gnats can provide useful information as they alert you to problems with your watering routine. When they do occur, it's often because your plants have been overwatered. Let's move on to our list of solutions that apply to all grow media.


• Less frequent watering


The first and foremost thing to do is reorganize your watering routine. If soil is your growing media, allow the soil to dry completely between waterings. Most of the time, if you do this, the fungus gnat problem will go away on its own. If you're not sure how often to water, you can lift the pot to see if it's lighter than it did the last time you watered.


• Yellow sticky traps


Get yellow sticky traps from the garden shop and place them around your plants. These will help controlling the number of gnats as your plant grows.




- Irrigate from the table. Since fungus gnats live and reproduce in the soil, their reproductive cycle will be disrupted and they will disappear from your growing area only if their entry and exit from the ground(medium) can be prevented. Mulching with perlite or gravel may be a solution for small infestations, but may not provide a definitive solution for every infestation. Continuously spraying around your growing area and disinfecting the inside of your growing area will greatly reduce your chances of having problems. When you irrigate from the table, the surface of the material you use in your mulch application will always be dry and the application efficiency will greatly increase.


- Use diatomaceous earth. Watering from the header will leave your mulch layer dry. Thanks to the 0.2-0.5 cm thick diatomaceous earth that will be sprinkled on the 2 cm perlite layer you use, when adult gnats land on the soil to lay eggs, micron-scale diatomaceous earth will stick to them and will dehydrate them and destroy them. Similarly, pupae and larvae that try to get out of the soil or roam on the surface will perish. If the diatomaceous earth and perlite layer is kept dry all the time, you will not have a gnat problem. When transferring from small pots to large pots, the top layer must be constantly renewed. Bottom irrigation is a method that makes possible the only alternative solution that mosquito-prone people can use when they do not have access to bacterial products.


Fungus gnats are very stubborn and as we mentioned, there are few ways to get rid of them. As LEDWisdom, we have shared with you the methods we use in our test greenhouses to help you get rid of fungus gnat problems. In our next article, you can find similar diagnosis and solution suggestions on spider mites. If you want to be notified when our article is published, you can subscribe to our site.

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