Influence of bunch exposure in a commercial Queensland vineyard on chardonnay and shiraz fruit and wine quality

Abstract

Queensland wine industry development has relied upon adoption of viticultural practices from established winegrowing regions. Such procedures are not necessarily best practice under Queensland conditions. The wine grape growing regions of Queensland are climatically distinct from other Australian regions with relatively wet growing seasons, sometimes with severe peak heat loads. Queensland also hosts the most northerly and some of the highest altitude vineyards in Australia, with higher ultra violet radiation exposure than any other Australian grape growing region. Furthermore, fruit exposure may be exacerbated by regional management practices used to minimise risk of fungal infection. The Queensland wine industry has identified fruit exposure management as a critical issue to be addressed. We studied the impact of management options on exposure of Chardonnay over the 2008/9 vintage, extended during 2009/10 to treatments in Chardonnay and Shiraz in the Granite Belt, South Burnett and Scenic Rim. Demonstrated options included sprawl, VSP, fruit zone leaf removal at pea size and véraison (morning sun or both sides of canopy), bird netting, or commercial sunscreen products (calcium carbonate or kaolin clay). Differences in fruit exposure, grape and wine quality were noted in 2008/9 as well as 2009/10. Growers inspected the demonstration sites prior to harvest and provided feedback on fruit quality. Fruit has been harvested, analysed and wines made. Analyses are being compiled for discussion along with sensory evaluation of the wines by industry personnel at a workshop in June 2010. Results of these analyses will be presented at the AWITC. This work is supported by the Queensland industry and GWRDC RITA grant RT08/03-1 “Addressing fruit exposure and sunburn in Queensland wine grape vineyards”.