Weeding carrots and carrot fly
We have grown carrots for a number of years now and we always have carrot root fly grubs in them. We have tried covering the seed bed with both fleece and enviromesh for the whole growing season. We only take the covering off to enable us to thin and weed, only for a matter of less than an hour at any one occasion. This year the infestation has been particularly bad and the grubs seem to go on eating their way into the carrots all through the winter. What is the answer to this problem?
It is possible that the flies are gaining access to the crop during these weeding sessions. Carrot fly are attracted by the scent released from bruised foliage. If you have to weed carrots, do it on a dry evening with no wind when the scent of the carrots will not spread so far. Pull carrots for eating in the evenings too, for the same reason.
Earth up and mulch
Try earthing up around the tops of the carrots and also applying a 2cm layer of grass clippings around the plants. This prevents flies gaining access to the surface of the soil where they lay their eggs.
Garden Organic members can see our factsheet about Carrot fly for more information.