03 May 2013

Bosman Vintage Report and Sugar Loading

Sugar Loading is a term new to me. This vintage report by Heinie Nel, viticulturist at Bosman Family Vineyards, explains what it is and how he uses the process to pick his Pinotage and Shiraz grapes at the point they reach ripeness.

Heinie Nel, viticulturist at Bosman Family Vineyards
The 2013 harvest is in the cellar and we are very excited about the quality of this vintage.

The growing season started off quite good. Our rainfall in the previous year (2011) was 537 mm and during this year (2012) we measured 727 mm of rain. We started off with good soil moisture and enough water for the growing season. Our own little "Hurricane Sandy" struck from November 28 - 30 2012. We had wind speed of up to 110 km/h, the average being 65 km/h. Many of the shoots and leaves in the vineyards were lost and damaged. The vineyards never recovered fully and immediately after the wind, we had maximum temperatures of 39°C - 42°C. Fortunately there was very little sunburn damage, but at this time we were all starting to become a little negative about the season.

Things did shift to become more favorable during the second half of December and the first half of January when temperatures were cool which is perfect for veraison.

Most of the cultivars were estimated to be about ten days later than normal except for Pinotage and Viognier which was estimated to be 5-6 days earlier.
We do sugar loading on the red cultivars to determine this. Sugar loading is when we take 100 berries, weight them and test its sugar. All measurements are plotted on a graph and when it stops ascending, you know the grapes are starting to reach full ripeness.

For example, we normally harvest the Shiraz on 25-26 ° Balling, but with sugar loading we established that we already achieve full ripeness on 24 ° Balling. During the tasting of these wines we had very positive results. We will continue with this practice to see whether we can harvest grapes at lower sugar levels and still reach optimum ripeness.

Source Bosman Family Vineyards Autumn 2013 (May) Newsletter


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