Grape quality

A welcome side effect of treating fungi (e.g. peronospora plasmopara viticola) with iron blue is the fertilizing of vines in soils that give rise to chlorosis. Leaf color is intensified, ageing of the leaves is retarded, and wood quality ( ripeness ) is also improved [3.196]—[3.198]. Iron is necessary for chlorophyll synthesis, which improves grape quality and yield. Other iron salts do not have this effect [3.197]. 

Abstract Wine quality strongly depends on the grape quality. To obtain high-... 

Leonard, O.A. and L.A. Lider (1961). Studies of monuron, diuron, simazine and atrazine on weed control, grape quality, and injury to vines. Amer. J. Enol. Citic., 12 69-80. 

The selective use of CM depends on the intentions and quality percepts of the producer. However, realizing its benefits depends on grape quality (appropriate ripening stage, state of health, etc.). 

Mildew and Botrytis Control. Control of mildew is the major fungicide problem in North Coast vineyards. Occurrence of mildew and botrytis affects the grape quality, and mildew has been shown to have a negative effect on wine quality (4). Mildew is controlled by sulfur applications, and nearly all North Coast vineyards receive four to six sulfur applications each year. The North Coast has less mildew and insect problems than does the San Joaquin Valley, attributable to a cooler climate and shorter insect seasons. 

Differences in microclimates, soil types, and general climatic conditions are difficult to measure and relate to grape quality. Most of the advancements in adapting the right grape to the right location have come about by... 

Our results have led us to suggest a role for L-ascorbic acid in phloem transport (9) in which ascorbic acid is translocated from its biosynthetic site in the leaf to a catabolic site in the fruit cluster where C4-C5 cleavage of the carbon chain produces tartaric acid and a putative C2 precursor of carbohydrate biosynthesis. The sugar/organic acid balance that influences grape quality in winemaking may well be determined by the role of ascorbic acid as the precursor of tartaric acid. 

Day, R.E. (1981) Juice preparation procedures. Proc. Grape Quality Assessment from vineyard to juice preparation. Aust. Soc. Vitic. Oenol. Adelaide, pp. 57-65. 

R.G Dambergs, D. Cozzolino, W.U. Cynkar, L. Janik, and M. Gishen, The determination of red grape quality parameters using the LOCAL algorithm. J. Near Infrared Spectrosc. 14(2), 71-79 (2006). 

Clary, C. D Wang, S. J., Petmcd, V. E 2007. Improved grape quality using microwave vacuum drying associated with temperature control./. Food Sci. 72(1) E23-E28. 

Temperature is one of the most important parameters of grape maturation and one of the essential factors that triggers it. Temperature affects photo-synthetic activity, metabolism and migration intensity in the vine. Its action is not limited to the period of grape development. Its influence on bud bmst and flowering dates also has important indirect consequences on grape quality. It is easy to... 

Most high-quality wines are produced in areas where annual precipitation does not exceed 700-800 mm. Evidence indicates that high rainfall and excessive irrigation are detrimental to grape quality. 

Thus the cUmate/quality relationship can only be represented approximately. The sum of the temperatures, rainfall or length of light exposure does not have the most influence on grape quality, rather, it is their distribution in the course of the vine growth cycle. 

In northern vineyards, climatic conditions favoring a forward growth cycle permit grape maturation dming a warmer and sunnier period, thus benefiting grape quality. Recent years have permitted the verification of this simple observation in the Bordeaux region (France). 

Choosing a variety for a given area depends greatly on its ability to reach a sugar concentration of 180-200 g/1 during maturation, but ripe grape quality is also affected by other chemical constituents. 

Vine management and growing are characterized by severe measnres limiting vegetative development and the amount of fruit. A certain canopy surface is required for grape alimentation and a relationship exists between this snrface and grape quality. 

The development of the canopy surface to fruit weight ratio can be used to evaluate grape quality. In an example with Tokay, Kliewer and Weaver... 

In a warm and sunny climate, increasing canopy surface and improving sun exposure combined with controlled irrigation will often increase yields without lowering grape quality (Bravdo etal., 1985), but several consecutive abundant crops can lead to depletion of vine reserves. 

Diverse causes can result in more or less severe vine defoliation. Maturation is difficult due to insufficient grape alimentation. A late downy mildew attack can cause total leaf loss in certain very sensitive varieties, such as Grenache. Similarly, leaves infected with powdery mildew always lower grape quality. Parasite development leads to significantly reduced crop yields, and very late attacks hinder grape maturation. 

B. cinerea development, alone or associated with other microorganisms, lowers potential grape quality. The enological consequences are serious in wines made from altered grapes oxidations, degradation of color and aromas, and fermentation and clarification difficulties. The objective measurement of the sanitary state of the harvest therefore presents an obvious interest. 

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