Under the stewardship of Gimblett Gravels technical group facilitator Heidi Stiefel, a small team of dedicated people is trying to identify issues that need to be addressed in the vineyard to ultimately improve the quality of wine product.
Two issues are currently being researched.
Better quality
Grapes from the Gimblett Gravels often have very low levels of yeast-available nitrogen (YAN).
This can result in difficulties with fermentation. The aim is to achieve acceptable levels of YAN in the gape juice by applying nitrogen in such a way that grape yield, wine quality and the receiving environment are not compromised. A range of nitrogen treatments has been established to help identify environmentally sustainable management options. Micro-vinification is being carried out on batch samples of grapes at harvest to assess treatment effects on wine quality.
Supporting data are being collected to describe the microclimate, changes in soil moisture and soil nitrogen, and to monitor the growth, biomass allocation and nitrogen budget of the vines.
The data is being used to develop a model for the water and nitrogen budget of the vines and to assess the environmental ‘footprint’ of vineyard production.
Mealy bugs
The second issue being addressed in the Gimblett Gravels region is mealy bug. A very common issue for vineyards around the world, it is a carrier for the plant virus ‘leaf roll’ that can interrupt the growth and function of vines.
A small research project was set up to identify the species of mealy bug present and to see if mealy bug can be monitored using sex pheromones.
Working with HortResearch, the project was able to identify one particular species, a significant find as management and control (chemical and biological) differs according to the species.
As a consequence, HortResearch is now approaching its US research partner to develop a specific pheromone to trial on the Gimblett Gravels blocks.
Wineries recognised as being part of the Gimblett Gravel group include: Babich Wines, CJ Pask, Craggy Range Winery, Gimblett Gravels Vineyard, Villa Maria Estate, Esk Valley Estate, Vidal Estate, Te Awa Winery, Trinity Hill, Goldwater Estates, Delegat’s Wine Estate, Mills Reef Winery, Sacred Hill Wines, Mission Estate Winery, CrossRoads and Squawking Magpie.
The Gimblett Gravels wine growing district is situated in Hawkes Bay, west of Hastings, covering an area of approximately 800ha.
The region was first planted in grapes in 1981, with merlot, cabernet sauvignon and chardonnay.
Before 1991, only 20ha of the region was planted in grapes – growing to more then 200ha by 1997 with a further 400ha being plants since 1998.
Eighty per cent of the land is planted in red grape varieties, mainly merlot, cabernet sauvignon, syrah, malbec and cabernet franc with smaller pockets of tempranillo, grenache, pinot noir, pinotage, petit verdot, gamay noir and sangiovese.
The remaining 20% is planted in white varieties, mainly chardonnay, sauvignon blanc, viognier and pinot gris.