Trends in pesticide use and efficacy during 26 years of changing agriculture in southern England.
We report on trends in agricultural pesticide use from 1970 to 1995 inclusive in arable crops on the South Downs, West Sussex, U.K. Information is given on the proportion of cropped area treated with pesticides, the percentage spray area, the number of pesticide applications per field, and the number of compounds applied per field for herbicides, foliar fungicides and insecticides. Compared to national published figures, our data are broadly representative of the national picture; they provide a complete and detailed time series whereas national figures are available for only 7 out of the 26 yr. In general, the area treated (fungicides, insecticides) and the intensity of use (all three types of pesticide) increased over the 26 yr. The spectrum of activity of the herbicides applied to arable crops increased from an average of 22 weed taxa susceptible in 1970 to 38 weed taxa susceptible in 1995. The odds on herbicide and fungicide use in break crops were, respectively, 93% and 99% lower than average; odds on insecticide use in spring cereals were 98% lower than average. Comparing winter wheat on the most traditional farm (grass/cereal rotation) with the most modern one (monoculture winter wheat), the proportion of fields treated with herbicides was similar, but the odds on being treated with fungicides were 129% higher on the modern farm. Insecticides were used in only 2% of the fields on the traditional farm, while on the modern farm over the same time period, 79% of the fields were treated. This fits previously observed differences in wildlife abundance on the two farms.