GEZI is a fine meshed crop protection cover designed to keep small insects such as carrot root fly and cabbage fly off crops. It is manufactured from high quality UV stabilised polyethylene which will last for more than 8 seasons. GEZI is placed directly on the seed bed and the plants push the insect-proof net up as they grow. As such, it is important to allow 40-50cm of spare insect netting either side of the bed to allow space for the growth of the crop, e.g. a bed of 1.4m width would require the 2.6m wide netting. These garden net sized sheets are complete with hemming on all sides to prevent fraying. Can be held in place with stones, sandbags or pins.
The main threat to carrots is the Carrot Root Fly
The carrot fly (Psila rosae) is a serious and widespread pest. Adult flies are about 8mm long, shiny black with reddish head, orange legs and transparent wings. The larvae are 8-10mm long and creamy-white in colour. Carrot flies lay their eggs between late April and August - two to five times per season. The eggs are placed beside the young carrot. Out of those develop grubs which burrow into the carrots causing tunneling. Sometimes the foliage turns reddish brown. The crop is inedible and will rot in storage.
What can be done
Try and sow as lightly as possible to reduce the amount of thinning. Carrot fly operates by smell so be careful not to bruise the foliage. They are most active during the day so do your thinning/harvesting preferably in the evening.
They aren’t great flyers so a windswept site is ideal.
Vertical barriers are a good idea for single rows of carrots as the fly doesn’t travel more than 40cm above the ground. However gusts can carry them over the barrier.
Covers are very effective as the carrot fly is prevented from placing the eggs beside the carrots.
Mulching with grass cuttings can make it harder for the female flies to lay their eggs in cracks in the soil.
Never leave infected carrots in the soil overwinter as the pest can live on over the winter ready for your next sowing of carrots.
Avoid growing related plants like parsnips and celery near carrots, as they also attract carrot fly.
Crop Rotation will also help to keep the problem under control.