Benchmarking wine grape quality in the Swan Hill region for the 2005 vintage

Abstract

Benchmarking wine grape quality in the Swan Hill region for the 2005 vintage

Summary

A benchmarking study was conducted in Shiraz blocks in the Swan Hill district during the 2005 vintage, providing a comprehensive set of crop measurements against which growers can compare their individual crop management, fruit quality and economic returns.

Some participating growers hoped that the study would reveal aspects of their crop or management that most influenced quality. Instead it highlighted the complexity of grape production, and uniqueness of each site. The benchmarks enabled participants to see clearly that vine blocks must be managed according to the individual needs of a particular block in a particular season.

Contrary to suggestions that smaller berries produce more flavour components per kg, there were no significant correlations between berry weight and quality (colour, phenolics, pH or TA). There was also no significant correlation between crop load and harvest date, or between harvest date and fruit quality. Fruit from heavier crops had lower phenolics, colour and baumé. Vines pruned to leave more buds had higher bunch numbers and lower phenolics and baumé, although this had not been observed in previous years benchmarking studies.

Fruit quality was not reflected in gross returns. Return was a consequence of bunch number and weight, and varied 3-fold across the sites. Water use also varied 3-fold, and revenue generated ($/ML) from water used varied 6-fold. Participating growers had hoped that grapes would be made into wine, to provide a clearer link between management, berry components and wine quality. While winemaking would be a costly addition, it would enhance the value of further benchmarking studies.

Participating growers were encouraged to reflect on where their fruit was ranked for each variable measured in the benchmarking study, to support any management decisions. Towards maximising their crop potential, the Swan Hill growers were able to identify those parameters that would provide the greatest benefit to economic returns and crop quality.