The cropping system with winter wheat has changed considerably during the past fifteen years in the Netherlands. Crop biomass has been increased by use of new cultivars and higher levels of fertilizers and pesticides. The question which arises is to what extend the level of fertilization affects epidemics of pests and diseases, compared to the well‐known effects of pesticides and cultivars. Epidemics observed in the winter wheat fields of the Development Farming System project (DFS) at Nagele, in 1984 and 1985 provided data for this analysis. Higher levels of fertilization stimulated epidemics of yellow rust, mildew, snow mould, leaf miners and cereal leaf beetles in the fields. The magnitude of the effect was comparable to those of the pesticides used and the cultivars sown. The level of fertilization showed no effect on five other species. How these interrelations between cropping practices and the associated development of pests and diseases can be used to design an integrated approach towards cereal cropping and breeding is discussed.

In the Netherlands integrated arable farming systems (IFS) are being developed at three regional experimental farms, with region-specific crop rotations and cropping systems. Most pesticide and fertilizer inputs appear to be replaceable by non-chemical methods and organic manure, with economic results similar to conventional systems. The targeted reductions in pesticide use in the Netherlands' Multi-Year Crop Protection Plan for the year 2000 can already clearly be met. Further improvements of the prototype systems are considered. Recently started farming systems research for outdoor horticulture is briefly discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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EPIPRE is an integrated pest and disease management system for wheat based on on-line calculations of costs and benefits of pesticide treatments. It is field-specific and utilizes disease and pest incidences which are collected by the participating farmers. Incidences are transformed to severities through pest-specific relations with which a prediction of the epidemic is made according to an exponential development model. Integration of the epidemic over time, with multiplication by a pest-specific damage factor, delivers the expected damage till the end of the season, expressed as a fraction of the expected yield. Chemical control is only recommended when benefit of control exceeds total costs, including those for pesticide(s), labour, machinery and wheel-track damage. The current model needs improvement especially for the forecast of septaria blotch diseases, the field-specific quantification of the relative growth rates used and the damage relations of Puccinia striiformis and Mycosphaerella graminicola/Leptosphaeria nodorum. Also the cost-benefit analysis of the model can be improved, and it therefore, in the near future, needs contributions from research topics such as phytopathology, crop physiology, farm economics and information management. Using the model during the last 10 years has led to a reduced input of pesticides, which in its turn results in a lowering of production costs and a marked decrease in environmental pollution. Therefore future efforts to improve the model seem to be worthwhile. Historical contextEPIPRE, an acronym for EPidemic PREdiction or PREvention, is a computer-based advisory system for supervised control of pests and diseases in spring and winter wheat. Its development started in 1977 as a project of the Department of Phytopathology of the Agricultural University of Wageningen (NL) and the Netherlands Grain Centre. Initially its aim was to generate recommendations on chemical control of stripe rust (Puccinia striiformis) on individual fields of winter wheat. Later, the Department of Theoretical Production Ecology of the Agricultural University, the Research Institute for Plant Protection (IPO, Wageningen) and the Research Station for Arable Farming (PAGV, Lelystad) joined in. From 1982, further development of the system and support of the participants was achieved by the ]oint efforts of fundamental and applied research organizations and the extension service. The advisory model which resulted from the collaboration was tested and used on a routine basis by voluntarily participating wheat farmers.The system was introduced when cropping practice in wheat was changing considerably. New systemic fungicides were made available for control of diseases in wheat. Concomitantly, 417

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