摘要 : The effectiveness, economic efficiency and environmental impact of pest management practices were compared in conventional, low-input and organic processing tomato and field corn [maize] systems in northern California in 1989-96. ... 展开 The effectiveness, economic efficiency and environmental impact of pest management practices were compared in conventional, low-input and organic processing tomato and field corn [maize] systems in northern California in 1989-96. Pests, including arthropods, weeds, pathogens and nematodes were monitored. Although both crops responded agronomically to the production-system treatments, arthropods, pathogens and nematodes were found to play a relatively small role in influencing yields. In contrast, weed abundance was negatively correlated with tomato and maize yields and appeared to partially account for lower yields in the alternative systems compared to the conventional systems. Lower pesticide use in the organic and low-input systems resulted inconsiderably less potential environmental impact but the economic feasibility of reducing pesticide use differed dramatically between the two crops. The performances of the organic and low-input systems indicate that pesticide use could be reduced by 50%or more in maize with little or no yield reduction. Furthermore, the substitution of mechanical cultivation for herbicide applications in maize could reduce pest management costs. By contrast, pesticide reductions in tomato would be economically costlydue to the dependence on hand hoeing as a substitution for herbicides. Based on the performance of the low-input and organic tomato systems, a 50% pesticide reduction would increase average pest management costs by 50%. 收起