Thursday, March 15, 2012

Low yields in grapevines - Vintage 2012

This season grapevine yields in McLaren Vale have been lower than average.

We speculate this is due to three things we know about.

1 - High winds. Windy conditions during flowering and ripening.

2- Soil Moisture. Irrigation gives us some control, but we are heavily dependent on having seasonal rain in Spring. This season we had lower than average rainfall in December and soil moisture began to dry out. 

3- Low bud fruitfulness. The fruitfulness of dormant buds is determined during the previous growing season
(November 2010 to January 2011).

A fourth issue has worried us this year is rising salinity in soils. Did this have an effect on vine yields?

Severe salinity.
High soil salinity levels can have drastic effects on the growth and yield of grapevine crops.

Effects of Soil Salinity

Soil salinity has three main effects:

Increasing salt in the soil will increase the osmotic pressure. This results in reduced water availability and reduced growth.

Some elements or ions, especially Sodium (Na), Chloride (Cl) and Boron (B), may be toxic or poisonous to crops.

High proportions of Sodium in relation to Calcium and Magnesium can adversely effect
soil structure, and thus limit water, air and root movement in the soil.

Salinity is caused by;

• Ground water. In most cases from bore water or recycled water.

• Natural soil salinity. Examples of this being along the lake shore at Milang in Langhorne Creek or old swampy area near Silver Sands in McLaren Vale.

• Undissolved Fertiliser (usually from animal manure), or soil amendments like gypsum.

The soil test will tell us if any of these three are occurring, or if low yields is purely a combination of high winds, soil moisture and low bud fruitfulness.

Wednesday, March 7, 2012

2012 McLaren Vale Vintage - Part 2

Around the district grape harvesting is continuing at pace. Shiraz from Blewitt Springs and Clarendon, plus Cabernet Sauvignon is being crushed this week. Mourvèdre from the Sellicks Foothill is also ripe. The trend of low vineyard yields producing fantastic quality juice in the winery is continuing. Expectations are high that McLaren Vale will produce another classic vintage.

Left - The cloud streaked view from Inkwell Wines.

“Harvest has been perfectly timed, with cool weather conditions for maturing grapes,” says Bradley Cameron, who has spent the harvest driving tractor pick up in his family’s vineyards. “Red grapes have been looking really dark in the picking bins. That is always a good sign.”

Right - Grapes at the Patritti Wines crusher.

The vintage has not been without one dramatic turn. The McLaren Vale region received its average seasonal rainfall, all on one day. Moist air drawn down from the north west of Australia saw 60mm of rain recorded on the last day of summer. The rain event on Wednesday the 29th of February put nerves on edge but miraculously the teeming skies only caused a minor to pause in picking. Fortunately the district’s famous winds picked up after the rain and quickly dried vineyards out.

Once the puddles had dispersed tractors returned to work and wineries were able to restart picking within 48 hours. Bunches on the vine did not split and minimal late season disease has been seen as a consequence.

Right - Cabernet Sauvignon being harvested at Paxton Wines.

It is an honest assessment to label this a very good vintage. It could even be remembered as a great vintage if cool and dry weather continues through March allowing full flavour development in Grenache and other late season varieties. While the forecasts remain dry, optimism is high that Vineyard 2012 will produce wines the community is proud of.