Detecting and combating fungus gnats in indoor cannabis

## Introduction

Fungus gnats (Sciaridae) are common pests in indoor cannabis cultivation. The larvae of these small black flies live in the soil and feed on organic matter, but can also damage roots. This leads to growth problems and reduces the yield.

### Identify fungus gnats

- **Adult flies** are 2-4 mm in size, dark-colored and fly around sluggishly.

- Larvae** are white, approx. 5 mm long and have a black head. They live in the top layer of soil.

- Typical signs of an infestation are declining plant vitality and root damage.

## Preventive measures

- Improve air circulation**: Continuous airflow helps to keep the environment dry and reduce infestation.

- **Control watering**: Allow soil to dry out between waterings to make larval breeding conditions more difficult.

- **Insert yellow boards**: These help catch adult flies and monitor infestation levels.

### Biological control

- Nematodes (Steinernema feltiae)**: These microscopic worms attack fungus gnat larvae and are an environmentally friendly solution. They are applied with the irrigation water.

- Bacillus thuringiensis israelensis (BTI)**: A biological insecticide that kills the larvae in the soil.

## Chemical control as a last resort

If biological agents are not sufficient, chemical insecticides can be used. However, these should only be used as a last resort to minimize the environmental impact.

### Prevention and monitoring

- **Regular inspection**: Monitor your plants regularly for signs of fungus gnats.

- **Clean environment**: Keep the grow room clean and free of organic debris to prevent fungus gnats from colonizing.

## Conclusion

By combining preventative measures, biological control methods and controlled chemical application, fungus gnat infestations can be effectively controlled. Regular monitoring and good hygiene are crucial to prevent re-infestation.

## Pro Tips

- Use sterile soil to avoid larvae infestation.

- Keep the surface of the soil dry to make breeding conditions more difficult.

- Use nematodes several times per season.

- Avoid overwatering, as this promotes propagation.

- Change the gel plates regularly to maintain their effectiveness.