Experiments on the Control of Carrot‐willow Aphid in South‐west England 1961–1964

SUMMARY Six trials were carried out in Gloucestershire and Wiltshire on the control of Cavariella aegopodii Scop, on carrots between 1961 and 1964. The results of these trials are given and discussed. In each year, except 1962, the first alatae occurred on carrots during May and built up to a peak in June or early July. April sowings of carrots were more subject to attack than May sowings whereas June sowings mainly escaped attack altogether. Two to four sprays of demeton‐methyl and a single spray of demeton‐methyl plus a later spray of menazon gave effective aphid control. Granular apPl.ications of disulfoton and of menazon used as a top‐dressing to seedling carrots also gave good control, though their initial action was slower than with the spray treatments. Menazon granules applied below the seed gave good aphid control, but produced no corresponding yield increase. In 1962, aphid infestations were much later building up, with the first alatae only appearing on the crop in mid‐June. Consequently, early sprays of demeton‐methyl and menazon applied on 1 June were ineffective, so that the combined results of the two sprays gave poorer control than in other years. Carrot motley dwarf was only present to a small degree and so was unlikely to have any effect on yield.