(1)Haldor Fykse, professor Norwegian Crop Research Instituter,
e-mail: haldor.fykse@planteforsk.no

(2)Kirsten Semb Tørresen, researcher Norwegian Crop Research Instituter, e-mail: kirsten.torresen@planteforsk.no

Fykse, H., K. Semb Tørresen & E. Romstad (2004): "Production Systems and Plant Protection Requirements in Cereals: a Model Analysis of Long-term effects", Acta Agriculturae Scandinavica, Section B: Soil and Plant Science, 54:149-160.

Abstract:
The main models within the MILDRI modelling network for studying plant protection, PVNOR, a dynamic model which simulates the development of weeds and diseases in cereals, and FARMNOR, an economic analysis model for choosing and evaluating management practices, were used to predict the effect of different production systems on the need for plant protection measures, and the resulting yield and economic output in different climatic situations. The simulations were run for 22 years using historic weather data. The study showed that PVNOR reflected fairly well the changing plant protection problems and agricultural consequences which emerged during the simulation period, and that the model handled the interactions between the large number of variables involved in such perennial systems. The combination of PVNOR and FARMNOR proved to be a valuable analytical tool, which in addition to predicting plant protection problems and consequences, also allows the prediction of resulting economic outcomes arising from different cereal production systems.

Key words: Crop rotation, diseases, economics, reduced tillage, weather conditions, weeds

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