This project will build on results from project AWR 1701-4.1.1 and aims to:
- understand the drivers of vintage compression between varieties, and within and between regions
- evaluate models to predict variation in harvest date within a region
- evaluate the management options to spread the maturity for red varieties in commercial regions that use machine pruned systems, and
- assess the risks associated with delaying maturity in current and future climates.
Anecdotal observations and the analysis of fruit maturation records suggests that, in addition to earlier maturity due to climate change, the period over which the fruit ripens is getting shorter. This is potentially caused by a convergence in maturity of early and late maturing vineyards of the same variety within a region; the convergence of maturity between different varieties within a region and the convergence in maturity of varieties grown in different regions. It places increasing pressure on harvest and processing logistics. A better understanding of the causes of vintage compression will allow better decisions about planting and fruit sourcing.
Phenology data for key regions and varieties will be added to an existing database and used to assess trends in fruit maturity between vineyards of the same and different varieties, both within a region and between regions.
Field trials will be established to assess management options that can delay maturity of red varieties in order to evaluate the impact of these treatments on fruit maturity, yield and quality.
Existing phenological models will be evaluated for their ability to predict vintage compression, improve our understanding of its drivers and the likely change over time.
By improving our understanding of vintage compression and options for its management, this project will increase the proportion of the crop that is able to be harvested at optimal maturity. This will avoid yield and quality loss due to the delayed harvest of over-ripe fruit and result in higher returns for Australian grapegrowers and winemakers.