Assessment of winegrape value in the vineyard-Survey of cv. Shiraz from South Australian vineyards 1992

In a previous survey of over one thousand individual vineyards (Gray et al. 1994), records of specified vineyard characteristics were compared during three years with assessments of potential value of the wines made at preliminary allocation to wine product ('Value Index' - 'VI'); significant relationships were infrequent and inconsistent. This paper reports the results from a more focused survey examining 148 cv. Shiraz vineyards in one year with an improved set of vineyard characteristics ('scoresheet'). Linear regression analyses showed small trends for lower 'VI' from vineyards with leafy, dense canopies, poor fruit exposure, lower anthocyanins, larger berries and higher yields. But the high variability of the data precludes reliance on these vineyard assessment methods, particularly as the assessments made at ripening were less successful than those made at harvest