Grubs/Maggots

[BrianMc]

Sciarid fly are attracted to rotting or decaying organic material, whether that is the plant or the compost it is growing in. I remember peat based composts were always a problem when wet, but the problem could be alleviated by using John Innes composts with its reduced peat levels. Allowing compost to dry out in between watering disrupts the life cycle of the sciarid fly, but does not prevent it entirely. The major problem I always found was seed raising. Allowing the compost to dry out to a point where sciarid are not a problem usually impacts on the growth of the seedlings, often causing them to be stunted or worse!
For a good number of years, using JI compost with added grit I haven’t had much of an issue with Sciarid fly. However, this year, with the dramatic decline in the quality of available shop bought composts and basically the disappearance of ‘real’ JI compost I have found a massive increase in the sciarid fly population in my greenhouse. My feeling is that the materials being included in composts now are not properly composted, so there is a large proportion of decaying material in our plant pots. I have also noticed an increase in fungi fruiting bodies. I assume all this is probably down to the quick turn around time in the process to maximise profits. It’s a disappointing situation that I don’t see being resolved easily.