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Tractor spray applications of a pyrethroid insecticide combined witha fluorescent tracer were applied to cereal field edges on four separate occasions in the autumn. Spray drift measurements were made in field boundaries adjacent to conventionally sprayed and 6-m-wide unsprayed "Conservation Headlands," which act as buffer zones designed to keep the outermost edge of the crop unsprayed with certain pesticide groups. The volume of drifting spray reaching field boundaries was dependent upon wind conditions and was significantly reduced by the useof these buffer zones. Comparisons of spray drift are made with comparable experiments carried out in summer cereals (reported in an accompanying paper). In a separate experiment, high mortalities of Spodoptera littoralis Boisd. larvae were recorded when they were exposed tograsses collected from hedge bottoms adjacent to conventionally sprayed headlands, and from additional spray applications made with a hand-held sprayer (used to simulate the levels of drift recorded in field trials). Larval mortalities were reduced, but still detectable, when grasses contaminated with drift adjacent to Conservation Headlands were bioassayed. In light of these findings, the current recommendation of these 6-m-wide buffer zones in cereals is discussed. [ABSTRACT FROM AUTHOR]

The drift of fluorescent tracer in water and formulated pesticide sprays was measured at different heights and distances within 6-m-wide buffer strips ("Conservation Headlands") and field boundaries surrounding mature winter cereal fields. Spray deposits were taken from artificial collectors. There was a diminution in deposition at the hedgerow, where a 6-m-wide buffer strip of unsprayed crop was employed between the sprayer and the hedgerow compared to where the entire crop edge was fully sprayed. There was some evidence that a mature crop would absorb some of this spray drift, reducing deposition on the hedge flora below crop level and, therefore, the nature of the buffer strip as well as it's width were thought to be important in determining hedgerow deposition rates. Frequency distributions of deposition along strips of hedgerow revealed that the unsprayed buffer zone also servedto reduce the peaks in drift that might occur as a result of the pitch and yaw of travelling tractor booms. The vegetational complexity of the hedge bottom was also shown to determine spray deposition within field boundaries. Larvae of the cabbage white butterfly (Pieris brassicae [L.]) showed higher mortalities when exposed to hedgerow grasses adjacent to conventionally sprayed headlands compared to those adjacent to a Conservation Headland. A simple methodology for spray deposition studies is outlined, and implications of pesticide drift into field boundaries discussed. [ABSTRACT FROM AUTHOR]

The effects of pesticides on beneficial predatory arthropods have been widely studied; this paper however deals with their effects on Heteroptera, an important beneficial insect group and food source for farmland birds. Field trials were used to evaluate pesticide effects under realistic conditions of application on a commercial arable farm and compared with previously published laboratory findings. Fungicideswere found to produce very low levels of mortality, not significantly different from control treatments. Aphicides varied in their impact, producing non-significant to highly significant mortality levels. The likely ecological impact of pesticides on various heteropteran groups found within the field and field boundary is discussed. [ABSTRACT FROM AUTHOR]