SUMMARY Counts of Aphis fabae Scop, eggs in winter and of the active stages in May on the spindle bush, Euonymus europaeus L., are used to predict the need for chemical control of the black bean aphid on spring‐sown field beans, Vicia faba L. For the purposes of forecasting, most of England south of the Humber is divided into 18 areas for which separate forecasts are made. A level of 5 per cent of plants colonized on the SW. headlands of fields in early to mid‐June is used as an economic threshold above which control measures are justified. From 1970 to 1975, area forecasts of the probability of attack were successful. According to the sampled fields there was considerable annual variation in the size of infestations, ranging from widespread, potentially damaging populations in 1973 and 1974 to very small populations in 1975. There was also considerable variation between areas: for example, in East Anglia and the East Midlands treatment was justified only in 1973 and 1974, whereas in Hampshire and Worcestershire/Herefordshire treatment was justified in all years except 1975. It was estimated that, from 1970 to 1975, control based on forecasting would have led to a gain of £11·4/ha over no treatment, and £3·8/ha over correctly timed routine preventive treatment applied annually irrespective of the aphid situation.

SUMMARYField trials in south eastern counties of England over the period 1967‐72 have been carried out on sites infested by the cereal cyst‐nematode, Heterodera avenae. In the main, spring barley was the cereal used, since this is the dominant cereal grown, and during this period resistant cultivars became available. Behaviour of soil populations of this nematode was erratic, but resistant cultivars from the Welsh Plant Breeding Station, based on Rika/Proctor, consistently lowered the nematode population in the soil, and outyielded more modern susceptible cultivars on infested soils. Evidence was found, in 1972, of a reduction in viability of cysts, associated with disease.

S U M M A R YSurveys in 1974-75 in which 20 plants were examined in each of 105 fields showed that cabbage stem weevil was widespread on spring oilseed rape in the south of England, the larvae sometimes infesting a large percentage of plants and reducing vigour and yield. In replicated field trials during 1974-77, infestations were reduced by seed treatments of gamma-HCH or sprays of gamma-HCH, azinphos-methyl, azinphos-methyl + demeton-S-methyl sulphone, chlorpyrifos or triazophos. In some experiments treatments significantly improved plant growth or yield, or both. Granules of carbofuran or phorate also reduced larval infestations and damage, but both thiofanox granules and dimethoate sprays were ineffective. Sprays of

SUMMARY Following several cases of serious damage to winter oilseed rape by cabbage stem flea beetle in eastern and south‐eastern England, surveys and obsei‐vations throughout England from 1974 to 1979 showed that infestations occurred mainly in Buckinghamshire, Cambridgeshire, Huntingdonshire and Northamptonshire; the heaviesl attacks also occurred in these areas. Minor infestations were recorded locally in 13 other counties. No attacks occurred elsewhere in England.

SUMMARYDisulfoton or phorate granules or demeton‐S‐methyl, menazon and vamidothion sprays, applied once in early June as preventive treatments before heavy aphid colonies developed, gave good control of Aphis fabae Scop, on field beans. Phosalone gave relatively poor results and DDT was ineffective. Applications in June to crops sown in February and early March were made with minimal wheel damage to the crop and are known to be less harmful to bees than sprays at flowering time. Eradicant treatments with demeton‐S‐methyl and dimethoate sprays or with disulfoton or phorate granules on heavily infested plants during flowering were also effective, but menazon was less satisfactory. These eradicant sprays are likely to be harmful to bees, and wheel damage in late June reduced yield by 1–2 cwt/acre (125–250 kg/ha).Peak populations of 3000 aphids/plant in early July reduced yield by 6 cwt/acre (750 kg/ha) in one trial.