Growing Futures

Optimising vineyard yield

Optimising vineyard yield

Managing grape volume to ensure a consistent supply of wine reaches the market is a key factor in the profitability of the wine industry

Image of a thinning machine at work

New Zealand produces less than 1% of the world’s wine, but is recognised as a premium producer. The Marlborough region in the South Island is particularly regarded as one of the premier producers of Sauvignon blanc, delivering novel flavours that command a premium in the global marketplace.

Managing grape volume to ensure a consistent supply of wine reaches the market is a key factor in the profitability of the wine industry, as excessive volumes of wine can reduce the premium price the industry can command in the marketplace. Excess crop load can also result in under-ripe berries and a dilution of the compounds necessary to produce a high quality wine.

Thinning the vines

Statistical models that predict the potential productivity of Sauvignon blanc grape vines based on weather conditions guide vine management decisions and allow growers to thin their vines to manage yield. To support these models, adaptations have been made to New Zealand-built machine harvesters, reducing the costs of thinning fruit, traditionally done by hand, by 60%.

Thinning the vines has also had a spin-off effect on the levels of botrytis bunch rot disease in the vines. Chemical control of Botrytis cinerea, one of the causes of bunch rot in grapes, can cost the wine industry upwards of $15 million each year. Mechanical thinning of the vines has been shown to reduce the level of botrytis significantly compared with hand thinning, and supports the wine industry’s target of reducing pesticide use to meet the demands of markets with increasingly strict restrictions on agrichemical use.

Future innovations

New projects are investigating the potential for machine thinning for other varieties of grape. Growers of red wine grape varieties are particularly interested in the technology as mechanical thinning has been shown to reduce berry size and this may lead to new colours and flavours in the wine, providing an opportunity for further differentiation in the global marketplace. Investigations are also underway to adapt different models of harvesters for use in mechanical thinning.

New Zealand Winegrowers is funding an ongoing series of research projects to develop tools to manage vineyard yield better. The Sustainable Farming Fund, vineyard and wine companies, and harvester operators are also providing support for these research investments.

Created: September 2012

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