Wednesday, March 20, 2013

Vintage 2013 #v13 UPDATE - 20/3/2013

Vintage 2013 is almost completed in the regions we operated in. McLaren Vale experienced very dry conditions from late spring into summer, the Barossa also had a drier than average winter - so to the Southern Fleurieu and Adelaide Hills where wet conditions are generally more prevalent. 

EL-47 shown by Brad Cameron at Aldinga - 17/3/2013

Vineyards are showing leaf fall much earlier than would be expected.  Windy conditions overnight, 20th into the 21st of March, has further increased leaf fall. When a vine has been so deprived of water it can exceed what is known as its permanent wilting point. At this point, the vine can prematurely drop leaves even if later watered. In some cases this has likely occurred because of very dry conditions with no significant rainfall for several months. 

It was a very early vintage and continues the trend of compressed ripening we have experienced since the mid-2000’s. 

We are often asked is this due to climate change? That is beyond our knowledge but this season was demonstratively hot.

This weeks CropWatch McLaren Vale has a graph of accumulated Biologically Effective Degree Days (BEDD) which demonstrates how this season was hotter and what effect it had on grapevines. 


Above: Accumulated Biologically Effective Degree Days, BEDD, for the 2013 Vintage compared to the last three seasons (2010, 11 & 12). Click on the graph for a larger image. 
Biologically Effective Degree Days are a tool used in phenology. They are a measure of heat accumulation and can be used to predict plant development rates such as the date that plants will flower or reach maturity.

Looking at this season the summary shows that we had a warmer than average late spring and summer. The season began to ‘heat up’ from November 2012, shown by the 2013 (red line) and average (green line) separating, compared to the sum of the last three seasons. This trend continued through summer.

Put in plain language the season was warmer than the average of the last three years from Nov-Feb which explains why harvest was earlier than expected. 

The warm and dry season had some positive effects on the grape harvest, but also some negatives. 

Sunset in McLaren Vale by James Hook.
On the negative side crop yields were low and high day and night time temperatures affected fruit quality in some cases. A few Cabernet Sauvignon vineyards were not harvested last week because of shrivel and sun damage.

On the positive side - no significant disease issues were reported in well managed vineyards. Some early season powdery mildew issues were seen in abandoned Chardonnay vineyards (these were not picked this year) but disease pressure was not high enough to spread this into neighbouring properties. No rainfall before harvest prevented any significant botrytis. Grapes were generally clean and healthy.

The only pest and disease issue of note was an increase in the amount of rust mite bronzing on vine leaves. 

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