Pests & Diseases > Fungus Gnats

Cause

Are associated with damp, poorly drained soils. The adult flying insects lay larvae that will hatch from eggs laid in soil and feed on the new roots of plants, causing wilt. Watering regimes and techniques must be checked. Potting mixes may be altered to create better drainage using sand or perlite mixes instead of peat. 

Prevention

Ensure that potting mix is not too wet or over-fertilized. Ventilation during cool, wet weather is essential. 

Cure

Reduce numbers of adult Gnats by hanging sticky traps in the growing area. These are easy to make using yellow cardboard covered in Vaseline or can be purchased from Horticultural Suppliers. Stop over-watering.