GRAPE LEAF DIAGNOSIS IN THE PIEDMONT REGION

In Piedmont, North-Western Italy, about 90% of the wine grape (Vitis vinifera) production is obtained from vineyards managed by integrated production methods. Reference standards for leaf diagnosis that take into account soil, climate and genotype (cultivar and rootstock) conditions more frequent in the Region are lacking. The two main cultivars grown in Piedmont, ‘Nebbiolo’ and ‘Barbera’, which are providing the raw material for several kind of wines, were selected for a general survey of the nutritional status of vineyards. One hundred and twenty vineyards have been selected considering vegetative growth, yield, quality of must and absence of evident nutritional deficiency symptoms. The vineyards were located in different growing areas of Piedmont. Standard leaf analyses have been carried out on samples gathered at fruit set. These data were combined with those from the databank of the “Settore Fitosanitario” of the Piedmont Region and analysed statistically to determine a leaf reference standards for these cultivars in the Piedmont conditions. Standards were developed and are presented for three main wine growing areas, Albese, Astigiano and Alessandrino, characterised by different pedo-climatic conditions. A comparison with other standards is also discussed.