Definition: common misconceptions

Common cultivation techniques used in vineyards have been called into question. According to Anderson, dropping grapes before harvest to increase concentration is nothing more than a myth. The researcher conducted trials and found that regardless of the volume of fruit removed, there was no significant difference in the sugar concentration of the remaining grapes at harvest time. This finding also applies to early removal of grapes. "If you remove 40% of the grapes at veraison, it's even worse," says Anderson.Grapes from control vines that retained all their grapes reached the same sugar concentration as grapes from vines that were green harvested. While there may be some difference before ripening, this difference in density disappears once the grapes reach a potential alcohol content of 13% vol. Anderson admits, however, that there may be a difference in the aromas of the grapes, but in his opinion, this has no effect on the final wines. "Is it worth dropping grapes?" Anderson wonders. It should be noted, however, that these results are based on only one year of experimentation and remain to be confirmed by further trials.

Another contested dogma is that irrigation deficit improves quality. It has been proven that early water deficit improves wine quality by reducing vegetation and berry size. However, many winegrowers remain convinced that water rationing until harvest, which reduces yields by dehydrating the berries, is also a factor in quality. Martin Mendez-Costabel of the University of Davis wrote his thesis on this subject. His conclusions: late irrigation during the season affects yields but has little impact on the fruit or the composition of the wine. On the contrary, it allows the foliage to remain green, which continues photosynthesis. The berries therefore continue to enrich themselves with sugar and water. Late irrigation during berry ripening also reduces the pyrazine content, which is responsible for herbaceous flavours. His recommendation is to limit water supply to control vegetation and reduce berry size, then irrigate as soon as the berries reach a sugar content of 11% vol. This strategy limits yield losses without compromising quality.

Source: copyright vitisphere® - 27/09/2007.