Climate-related Risks on Agriculture in Demarcated Douro Region

The knowledge of the climate risks at small scales is yet essential for agricultural activities and production like vine growing, because of their serious economics impacts. We know that some meteorological processes operate over slightly restricted areas and may bring some risks to people due to their activity, like floods, fog and frost (Monteiro, 2003). This is what happens, for example in viticulture where the quality of the wine, the selection of the grapevines or even the characteristics of the farming soil, also depending from local soil features like topography, proximity of a river or water body, will act locally on the weather. Spring frosts are of significant concern to growers of many cultures crops such as winegrapes. Because of their high latitude and some altitude, the vineyards of the Demarcated Douro Region (DDR) are subjected to frost days, which cause serious damages. But the hazards of vineyard don't confine to the incidents of the fortuitous and/or meteorological character. The illnesses and plagues affect frequently the vineyards of DDR due, namely to the weather, to the high power of the regional stocks, to the dense vegetation badly drained and favourable to the setting of numberless fungi, viruses and/or poisonous insects. The gravepine is hostess to several enemies responsible for the appearance plagues or illnesses. These show disturbances which interfere with the normal structure, the physiological functions or the economic value of a plant visible through modified symptoms. At the level of developing factors concerning plagues or illnesses we have to notice the biotic causes (presence of insects, fungi or viruses) meteorological and cultural causes (used techniques). In the case of DDR it is worth noticing the meteorological conditions due to the weather characteristics. Although there are several illnesses and plagues the most important enemies for the vine in the DDR are the mildew, oidium, grey rottenness, grape moth,..., if the climatic conditions favour their appearance and development. The knowledge of frost and plagues occurrence allows one to decrease its risks not only by selecting the cultural species and varieties but also the places of growth and the planting and sowing dates.