Carrots are one of the more important foods in our diet providing a particularly high source of Vitamin A. Yet growing them successfully, to provide year round supplies, is beset with many problems. Stony ground or use of over ‑ fresh manures can cause forking; they are unhappy in soils outside the range ph 6.5 - 7. 5 and carrot fly (Psila rosae) often proves a persistent and damaging pest. This lays its eggs in the soil next to the plants, attracted both by sight and scent. Once hatched the thin, cream coloured maggots burrow into the ground and eat away the roots causing the carrots to rot if storage is tried. Attempts to control by chemical means have resulted in resistant strains of fly developing. At the same time harmful sprays can destroy the ground beetle which would otherwise eat up to 50% of the over wintering pupae. Birds to, eat large quantities from newly dug soil in the autumn. Supplies of the pest are constantly renewed from those living on cow parsley and hemlock common on uncultivated ground. Also other related plants (umbeliferers): celery, parsnip and parsley maybe attacked and acts as hosts to this carrot fly.
Research findings have led to improvements to older methods of cultivation aimed at beating the carrot fly. These are looked at more fully at our show but combinations of the following methods are proving most effective: sewing resistant varieties; physical barriers (fleece and screens); reducing scent by avoiding thinning; disguising scent by planting onions, garlic or aromatic herbs; taking note of carrot fly forecasts and of course encouraging the natural predators.
Members of H.D.R.A. are this year cooperating in testing Thompson and Morgan's new carrot variety `Fly Away'. Do come and tell us if you've tried it. Sewing dates, other varieties compared, barriers tried etc, will also be of interest.