A column soil elutriator (the Wye Washer) for extracting cyst nematodes and other small invertebrates from soil samples is described. Laboratory tests have shown the new equipment to achieve extraction rates equal to or better than existing techniques and to offer operational advantages also. Soil in quantities of up to 1 kg may be processed without drying or subsampling, the equipment can be left unattended once set to work, and can be used to extract a range of target organisms. There is only one working part (a valve) and no electrical parts, but water use and price is high. The Wye Washer is now used in the advisory entomology laboratory at Wye as the standard equipment for extracting cysts of Heterodera and Globodera, for eggs of cabbage root fly (Delia radicum) and for cocoons of black currant leaf midge (Dasineura tetensi).

During 1958–60, replicated insecticide trials were carried out in East Anglia in an attempt to assess seed losses on Trowse mustard (Brassica juncea) caused by larval infestations of the cabbage stem weevil, Ceutorhynchus quadridens (Panz.). The overwintered adult weevils invade the young growing crops during April and May, and the eggs are laid in the petioles over a period of weeks, depending both on temperature and crop stage, until about mid-June. Egg-laying began on mustard when the plants had produced six to seven broad leaves, but the actual time at which the first eggs were laid seemed to depend mainly on temperatures during May. In the insecticide trials, infestations averaged up to 26 larvae per plant, and none of the untreated plants entirely escaped attack.High rates of γ BHC (5 or 10 per cent, of the weight of seed) gave some control of stem-weevil larvae when kerosene was used as the sticker for the insecticide; 3 per cent, or 5 per cent, phorate and 5 per cent. Telodrin (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-methanophthalan) gave no control. The control by seed dressing was unreliable and is considered unsuitable for assessing yield losses caused by stem weevil.A single emulsion spray of dieldrin applied during May when the first adult feeding holes were found in the petioles, gave a good control of stem weevil and prevented egg-laying, and this technique seems promising for future work on damage assessment. It is thought, however, that sprays specifically directed against stem weevil would seldom be justified economically on commercial crops of Trowse mustard, but on April-sown crops the first dieldrin spray against blossom beetle, Meligethes aeneus (F.), may give some protection against stem weevil.The damage-assessment experiments gave no reliable indication of the effects of the stem weevil on yields of seed, in spite of their being sited in localities known to have a high weevil population. It was clear, however, that sowing date greatly influenced yields of seed; plants sown in March outyielded those sown in April or early May.

539 Field observations on the control of blossom beetles (Meligethes ueneus F.) and cabbage-seed weevils (Ceuthorhynchus ussirnilis Payk.) on mustard-seed crops in East Anglia . 540 A. L. WINFIELD briefly reported by Winfield & Gough (1959). The work was done mainly on the brownseeded Trowse mustard (Brassicu juncea Coss), and the choice of insecticides and the timing of the treatments have been based on the conclusions of the continental authors.In 1958 several insecticides were tested, and further field trials on spray timing were carried out in 1959. -41~0 in 1959 a small survey was carried out on several commercial crops of Trowse mustard in Norfolk, the Isle of Ely, and the Holland division of Lincolnshire.

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