Late frost devastation in Burgundy vineyards explained…

There were two successive weather phenomena that damaged the vineyards in Burgundy early this month. We refer to them as the late or “spring” frost, in French they call it “les saint glace”.

“Les saint glace” refers to a climatic period that was first used in the late middle ages by farmers who designated three dates: 11, 12 & 13 May each year as the latest dates where frost can take place. The three saints celebrated on those three specific dates are: saint Mamert, saint Pancrace and saint Servais. At that time and up until recently, this late frost rarely happened. But with global warming, this period has become somewhat more recurrent and feared!!

The first “frost wave” took place on the 6th & 7th of April, called the “black frost”. This was caused by a mass of very cold air descending on the vineyards. The use of candles and ventilators in the vineyards, whose purpose was either to heat up or to circulate the air, turned out to be inadequate as the mass of cold air was to big and heavy to be dispersed.

The second “frost wave” happened the next day, on the 8th of April, but this time as a “white frost”, where the buds that are frozen by the frost then burn from the first sun rays as the sun rises. (The humidity on the buds turns to ice when the temperatures plummet to sub-zero and this ruptures the plant’s cells. The early morning sun’s rays melt the ice and burn the cells. This is called “Radiational Freeze” and does permanent damage to the plant’s cells)

It is quite rare for these two phenomena to happen and even more so on consecutive days!

This early budding was due to the warm, sunny conditions at the beginning of April. Over a few days we saw temperatures that varied between +25°C and -6°C. Some wine experts believe that early pruning has not helped matters as this, along with warmer than average conditions, leads to early budding. There were some savvy winemakers who decided to prune the vines later than usual. It seems they made the right decision as their vines were less affected. However, most wine makers have stated that the vine plant’s sap flow streams have been perturbed and that they are not descending fully (as expected) as the winters are now no longer cold or long enough! The sap therefore rises early and quickly provoking the early bud burst when warm conditions start.

Although its early days to count the true damage to the vines, experts are predicting losses of between 50% and 80% in certain vineyard plots, in particular in the Côte de Beaune and Chablis districts.

What happens to the vines now? The Chardonnay varietal, which buds earlier than the pinot has been particularly affected. The second budding that will follow however, will not produce grapes!

The Pinot Noir varietal has more of an advantage as it buds a little later. However, if the bud is damaged, the second budding will produce smaller-sized grape bunches, meaning a much lower yield.

Burgundy has been plagued with various bad weather conditions since 2010, (mainly hail in the summer), and this has led to increasingly low yields, which has its economic “knock-on” effect and inevitably leads to higher prices!!

Climate change is shaking up the wine industry. Some winemakers have even threatened to quit the industry completely, a few believe the answer lies in changing the varietals. The answer may lie in winegrowers reviewing their vineyard practices. One thing is for sure, the current situation cannot continue and this climatic problem has to be addressed.

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