Agent against fungus gnats and fruit flies in potting soil

If small black flies frolic in the potting soil, this sight puts the hobby gardener on the highest alert. As a rule, fungus gnats have made themselves comfortable in the substrate to lay their eggs here. The larvae extract valuable nutrients from the soil and nibble on the roots, so that the plant is extremely threatened. Only rarely is it an infestation by fruit flies. This species of insect looks very similar to fungus gnats, but it targets ripe fruit. Bring your knowledge up to date on which means work against the plague.

Matches as an immediate measure

If you spot the first specimens of the sciarid gnats buzzing around the potting soil, an immediate countermeasure will prevent the brood from spreading explosively. Without further ado, stick a few matches upside down in the substrate. The released sulfur immediately kills the larvae. In addition, the adult mosquitoes are prevented from laying further eggs. Replace the matches every 2 days as the low sulfur content is quickly used up.
Tip:

Yellow stickers provide more information about the infestation pressure, as the adult fungus gnats stick to the glued boards. If a yellow sticky trap is covered with the 2-4 mm small, black two-winged birds, matches are no longer sufficient to combat it.

Insert a layer of quartz sand

The tiny flies and their larvae feel particularly at home in the moist environment of potting soil. Since letting the substrate dry out is out of the question, the following strategy corrects the problem:

• Repot the plant affected by fungus gnats
• Remove the infected substrate from the roots as much as possible
• Ideally, rinse off the root ball with lukewarm water
• Plant up to two thirds of the height of the pot in fresh, disinfected substrate
• Paste a 0.5 to 1 cm thick layer of quartz sand
• Spread the rest of the substrate over it

The quartz sand acts as a barrier for the voracious larvae. If you water the plant from below from now on, the upper substrate layer may remain very dry, so that it is no longer suitable as a breeding site for fungus gnats.

Nematodes

Nematodes have earned a good reputation in ecological pest control. These are tiny roundworms that are invisible to the naked eye. SF nematodes of the species Steinernema feltiae are very fond of the larvae of fungus gnats. The roundworms invade the brood to give off a deadly bacterium. How to apply the remedy:

• Put the nematodes supplied in clay mineral into water according to the instructions
• Pour the infested potting soil with the mixture
• Note the minimum temperature of 12 degrees Celsius
• Do not use in direct sunlight

As a result, the plant can be watered and fertilized organically or minerally according to the normal care protocol. Only the administration of lime affects the effectiveness of nematodes.

Predatory mites

If you are dealing with a die-hard generation of fungus gnats, the nematodes receive reinforcement in the form of predatory mites. Especially with the species Hypoaspis miles, the larvae are at the top of the prey scheme. The little predators first go through a few stages of development so that they do not act as immediately as nematodes. The mites compensate for this disadvantage by actively hunting down the pests for many weeks. This is how the application works:

• Predatory mites are delivered in an envelope with a peat-vermiculite mixture
• On the day of delivery, moisten kitchen paper and spread the predatory mites on it
• From the kitchen paper, sprinkle the granules with the mites on the potting soil
• Do not work the beneficial insects into the substrate

Leave the damp kitchen paper in the pot until the next day so that the remaining mites can migrate to the plant. Under optimal conditions of 18 to 25 degrees Celsius, they keep the earth slightly moist.

Mosquito-free

In the biological control of mosquitoes, a bacterium is used that does not spare the larvae of sciarid gnats either. The Bacillus thuringiensis israelensis concentrates only on the brood and leaves the plant undisturbed. In addition, it is safe for humans, pets or beneficial insects.

Proven home remedies

Environmentally and health-conscious hobby gardeners favor the use of traditional home remedies in the event of a pest infestation in the early stages. To effectively control fungus gnats and fruit flies in potting soil, the following approaches can be considered:

• Enrich the irrigation water with 20 drops of tea tree or lavender oil per liter
• Sprinkle the potting soil with cinnamon or baking powder
• Put garlic cloves in the infected substrate

Plagued gardeners cover the pot up to the root neck of the plant with a nylon stocking, which is closed as tightly as possible. In this way, the mosquitoes can no longer get to the potting soil and hatched larvae cannot come out. The escalating cycle of reproduction is thus interrupted. However, this measure takes 5-6 weeks, during which you have the not very decorative appearance of an ornamental plant in mind.

Chemicals

Although fungus gnats pose no threat to human health, an infestation of potted plants in the room prepares Conservatory, greenhouse and on the balcony great discomfort when clouds of pests emerge at the slightest vibration Raising potting soil. If all natural control methods fail, insecticides offer the last resort. These preparations will take the plague off your throat:

• Insect-free neem from Compo
• Pest-free Lizetan AZ from Bayer
• Organic pest-free Neem from Bayer
• Organic pest-free neem by nature

All preparations are based on azadirachtin, a chemical compound with the main component from seeds of the neem tree. Please use these insecticides strictly according to instructions, especially indoors.

Preventive measures

You can take the following precautions beforehand to ensure that sciarid gnats don't attack the potting soil of your plants in the first place:

Substrate

disinfect

Regardless of the manufacturer's promises on the packaging, commercially available potting soil can very well be interspersed with eggs and larvae of fungus gnats and fruit flies. You can be on the safe side by converting the oven into a sterilizer. That is how it goes:

• Pour the potting soil into a fireproof bowl
• Put the lid on loosely
• Heat in the oven at 150 degrees for 30 minutes

Microwave small amounts of substrate for 10 minutes at 800 watts. Also treat your own mixtures according to these instructions to ensure that there are no pests in them.
Tip: The sowing and propagation of cuttings is explicitly threatened by insatiable larvae. Therefore, subject every potting soil to a meticulous disinfection in the oven or microwave.
Mulching with sand

To prevent the female insects from getting into the potting soil, cover the surface with a 1 centimeter thick layer of quartz sand. In order not to have to renew the sandy mulch after every watering process, water the plant from below. To do this, place the pot in a bowl with a water level several centimeters high for a few minutes. Due to the capillary force, the water pulls up into the root ball so that the surface can remain dry.

Prefer hydroponics

Almost all house and container plants are suitable for hydroponics. In this variant, the plant thrives in an inorganic substrate such as expanded clay or seramis and water. Since no soil is used, fungus gnats and fruit flies have no chance to settle here and lay their eggs. Since switching from potting soil to hydroponics is not always successful, hydroponics should be preferred when purchasing young plants.

Carnivores

The use of carnivorous plants has been shown to be extremely effective in keeping sciarid gnats and fruit flies away. If you place at least 1 carnivore per window sill, the chances are that the potting soil of the neighboring house plants will remain free of pests.

Conclusion
The next time a swarm of tiny insects rises from the potting soil, you are now equipped to put a stop to the nefarious goings-on. The remedies against fungus gnats and their larvae presented here have proven themselves to be excellent in releasing a besieged plant in good time before it suffers significant damage. Moreover, those who follow the recommended methods of prevention do not even have to deal with fighting them. As a rule, they are not fruit flies. Although these insects look very similar to fungus gnats, they do not benefit from potting soil.