August 2011 Douro Insider

Grapes in evening sunlight

Unlike some months so far this year, August was by no means atypical; on the contrary, both the temperatures and the total precipitation were very close to average.  This makes it much harder to explain the extraordinary maturation of the grapes, but surely the very early veraison discussed in last month’s report must have been in part responsible.  Basically it was clear and hot and dry.  Perhaps the only real anomaly was that the habitual (and hot) evening winds were even stronger than usual but, contrastingly, there were also some surprisingly cool nights on occasions.  The upshot of this was the appearance of some refreshing morning mists, particularly on the high ground and at the coast.  Porto and Gaia were therefore untroubled by any really uncomfortable heat, and indeed many complained of a disappointing summer.  The usual round of forest fires struck around the middle of the month and brought a sinister yellow tinge to the air as the sun struggled to shine through the smoke haze.

The first couple of days of the month were the most unsettled, with some thundery showers occurring in the south of the country due to a depression in the Gulf of Cadiz.  The prevailing winds blowing in from the northwest initially brought down temperatures, but then the Azorean anticyclone began to dominate the weather again causing a return to the typical summer state of clear skies and more heat.  This did not last long, because almost immediately frontal systems crossed the north of the Iberian Peninsula and temperatures again dropped temporarily as more clouds amassed.  By the start of the second week, though, normal service was resumed as the mid-Atlantic area of high pressure grew and stretched inland as far as central Europe.  This pushed the mercury right up so that by the time the daily maximum temperatures peaked around the 12th we were looking at values into the 40ºs C.

Things continued in this vein until the good weather broke on the 21st, with a wet and stormy front rolling in off the Atlantic and dropping a refreshing amount of rain on the Douro.  It was enough to water the new plantations (thereby saving us a few cents per vine) and it also appears to have been sufficient to have had an effect on the maturation.  It might seem hard to believe that rainfall which appears not to penetrate more than a few millimetres into the topsoil can have an effect on such deep-rooted plants as adult vines, but the results of the maturation studies would indicate otherwise, with some of the Baumés dipping almost immediately (but temporarily).  They then picked up again with renewed vigour as photosynthesis was kick-started again after the heat.

The caseiros in the Douro all like to say that ‘the vines also drink through their leaves’ which, although viticulturally dubious (to say the very least) sometimes appears to be the case because the sudden drop in both temperatures and evapotranspiration improves the water status of the vines even if the rain is insufficient to penetrate as deep into the soil as the main rootzone.  The cloudy skies which followed the rain were responsible for a big decrease in temperatures which generally peaked only in the low 20ºs each day.  Whilst this was probably good for ripening in itself, it also brought nights that were cold enough for some heavy dews to fall – something which is not very normal in August and can be dangerous if the humidity gets into the tighter bunches, like the Francesa.  Amazingly, there were some days towards the end of the month on which the temperature didn’t even reach 20º in certain parts of the country.

The change in weather also brought some extremely windy evenings, although this time the wind was far from warm.  Indeed, it is fair to say that the end of the month was quite un-August-like, with plenty of clouds, cold winds and the occasional shower.  The mean for the month showed that August had been just fractionally below average, coming in at 24.4º (compared with 24.6º) although in truth it felt cooler than that.  Total rainfall in Pinhão was almost exactly spot on average too, just 1 mm above the long-term mean (17 mm).  Oddly, it was the first month so far this year to produce above average precipitation, if only by a minimal margin.  This takes this year’s cumulative total to just 252 mm, very significantly below the expected value of 386 mm.  Considering the warm spring, the vines are bearing up remarkably well.

Collecting individual grapes for maturation studies

Activity in the vineyards is usually quite limited in August, with most of the workers on holiday for at least most of the month.  This year was quite different, however, because as soon as the maturation studies got underway it quickly became apparent that the sugar levels were exceptionally high, as might have been predicted by the very early veraison.  As a result there were some red grapes from the Douro Superior (although not ours) harvested even before the mid-month holiday, and by the middle of the next week lorry-loads of white grapes were already becoming common on the roads around Pinhão.  Almost certainly this was easily the earliest start of the harvest in living memory in the Douro.

Miles in a vineyard after final despontas - vine trimming - has revealed the grapes for easier picking

Whilst phenolic ripeness lagged some way behind the sugar, the usual multitude of students took to the vineyards collecting grape samples for analysis, and the winemakers spent days on end tasting berries in the vineyards.  Basically these two activities geared towards getting the harvest date absolutely right took up the vast majority of our time.  When the vineyard workers returned from their summer holidays, in some cases it was immediately into the harvest.  At other quintas there was still a week or so of despontas to be done before picking started.  The pre-harvest despontas are important for two related reasons – they make the picking more efficient because the bunches become more visible, and the passage of machinery through the vineyards (taking out boxes of grapes, for example) is very much facilitated.

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