[Early warning systems for epiphytes caused by Septoria in Europe]
1990
Silfhout, C.H. van (Instituto de Investigaciones para la Proteccion de las Plantas, Wageningen (Netherlands))
After the introduction in Western Europe of chemicals for protection against diseases of wheat around 1970, farmers increased their demand for advice on how to use these chemicals. Since at first recognition of diseases by European farmers was limited, recommendations, although based on factorial trials over a number of years, were simple and of a general nature. They proved quite satisfactory when circumstances in which they were applied remained stable. Sometimes, however, these circumstances (i.e. crop, disease and weather) change; in that case, the farmer's and the advisor's knowledge and experience should also be used. In recent years warning systems to integrate existing knowledge and available data have been developed by research groups in Europe, especially in Great Britain, France, Germany, and the Netherlands. The main goal of warning systems is to predict the possibility and severity of the development of an epidemic of one or more diseases. In addition, some systems also predict the expected loss and compare it with the cost of applying fungicides. To facilitate the use of more complicated warning systems by farmers and advisers, simple methods have been developed to identify and score diseases. Most systems now used in Europe are briefly explained in this paper. In general thresholds are used to predict the development of an epidemic. These thresholds are calculated from data over a number (6-12) of years and are related to rain or humidity and temperature
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