July 2009 Douro Insider

It was extremely sticky right at the start of the month and really rather uncomfortable, but there was no hint of rain to bring relief. On the contrary, it was very sunny to begin with. After a few days it cooled slightly but there was still no sign of clouds – not in the Douro at least, although the second week was somewhat unsettled in Porto. It remained cool, sunny and humid inland and up the river, and things continued in this uninspired vein for some time. It was surprisingly not very hot for July in the Douro, and by mid-month there were even quite a few clouds around, unusually. On the face of it, it appeared to be typically unpleasant, sultry, oídio weather – although fortunately none was forthcoming.

There then came a dramatic change for worse with about 10 days left of the month, as a spell of terrible weather crashed into Europe from the west, bringing continent-wide flood damage and even causing some deaths. It was this vicious front that put and end to the short-lived ‘heat wave’ in UK earlier on in the month, and then went on to ensure that it became the second wettest July in the last 100 years over there. In Portugal we escaped comparatively (but by no means totally) unscathed. First of all heavy clouds rolled into Porto, carrying with them plenty of rain. The storm soon worked its way upriver, turning the Douro extremely unsettled, humid and thundery, with very high winds whipping up the dust into swirling clouds. There were moments when the skies had patches of blue, areas of dull overcast and black storm clouds all present at the same time, gradually dissolving into a sinister, sulphurous evening light.

The heart of the storm was disappointingly short on precipitation (unfortunately for the vines), perhaps because it had already dropped most of its rain on the more coastal areas. There were reports of flooding in Braga, and elsewhere in the north of Portugal rivers burst their banks. There were only really one or two serious rain showers across the Douro, whipped in by ravaging winds that were easily harsh enough to shred the younger leaves on a vine, but they were very localised and over quite quickly with minimal damage. There was one terrible evening that seemed more like December, however, with howling gusts rattling the windows and doors frenetically all night long. Thereafter things calmed down somewhat. There were some misty and overcast mornings (before the sun burnt through) right up until the end of month, keeping it cool in the city but during the daytime it warmed up considerably out in the countryside. This period brought some of the warmest temperatures of the month, but the nights nevertheless remained colder than would have been expected.

Principally as a result of this storm the official precipitation figures for Portugal actually show higher than average rainfall across the country, even if this was certainly not the case in Pinhão. At the start of the month 44 % of the continental territory was undergoing severe or extreme drought, a figure which had been reduced slightly to 40 % by the end. Temperatures were below average, although this news was tempered by an announcement from the National Oceanic and Atmospheric Administration. According to them, a new El Niño cycle has just started, meaning that we can expect warmer temperatures for at least the next few months.

Pinhão’s monthly rainfall was surprisingly low, with a total of just 3 mm to show for all the stormy weather. This compares unfavourably with a mean of 14 mm. Accordingly the gap between the two lines on our precipitation graph once again opens up, as this year’s cumulative total (currently a fraction over 280 mm) falls further behind the mean (370 mm). It probably goes without saying that July is normally the driest month of the year, just ahead of August.

As we have touched on already, temperatures were somewhat cooler than expected on balance (although the daily fluctuations were considerable).  Pinhão’s average value, at 23.2ºC, was way below the long-term mean of 24.7º. This negative deviation is the largest so far this year, and it is interesting to note that the absolute maximum temperature for the whole month was just 36.7º – one of only two days to actually climb above 35º. By historical standards this is clearly a cool July for the Douro, as the minimum of just 12.6º confirms. We should be grateful for this since lower temperatures reduce evapotranspiration from the vines, making it easier for them to get by on the little available water. The large blue block on the temperature graph is therefore very welcome.

The most important viticultural occurrence at this time of year is of course pintor (veraison). This is the point at which grape ripening can be considered to begin. Technically it is defined as the moment at which the bunches change colour, but physiologically it is the point at which the berries cease to grow by cell division and from then on the number of cells in the fruit is fixed. Hereafter berry growth is only possible by expansion of the existing cells rather than by further multiplication. It is also the time when sugars begin to accumulate in the bunches – hence the onset of ripening.

Interestingly veraison started very early this year, at least in the low-lying quintas, although there is no obvious reason why this should be so. Given the unsettled weather around the early to middle part of the month it is not surprising that, once underway, it proceeded rather slowly. This year there was also a high degree of heterogeneity between varieties, with the Touriga Nacional changing colour much later than the other castas. By mid- to late July pintor had worked its way up to the later, higher quintas and by that stage progressed rapidly due to the hotter temperatures. The average date for our experimental vineyard was the 19th July this year, which is considerably earlier than normal (somewhere in the region of a fortnight). Usually the central Douro wouldn’t reach this point until early August.

Veraison is generally greeted by a collective sigh of relief across the viticultural community. Significantly, it marks the point at which the berries become virtually completely resistant to fungal diseases (with the exception of low prevalence late-season bunch rots, such as botrytis, of course) and with any luck (insects permitting) we can now put away the sprayers. Ideally shoot elongation should stop at veraison, hopefully with the last desponta, but in practice this often turns out to be optimistic. The vines should then concentrate their efforts on ripening the grapes and not on producing more vegetation. The truth of the matter is that removing the shoot tips will almost inevitably encourage the development of some lateral shoots, and this is not necessarily a bad thing since it is this late flush of growth that will provide the last batch of productive adult leaves of the year, responsible for producing the sugar that is essential to the final stages of grape ripening. Desponta, therefore, was perhaps the single most undertaken activity in the vineyards in July. A few quintas were also still involved in the related practice of shoot thinning at the same time.

The onset of the really hot and dry part of the year makes it an excellent time for hitting stubborn and persistent weeds on the taludes (the banks of the terraces) as well as tidying up any spontaneous vegetation that might have sprung up in the vineyards after the residual effects of February’s herbicides have worn off. A second round of localised herbicide applications was therefore carried out by many farmers. A more physical solution to the same problem is of course ploughing between the rows, whilst at some other properties the mowers were in use once again. These versatile machines are not just essential for maintaining the cover crops that we plant, but they are an excellent ecological alternative to using weedkillers on the flat, whether in the vineyards or in the olive groves. Incidentally, olival maintenance was also required at several places this month.

As we have already seen, veraison hopefully marks the end of the annual programme of anti-fungal treatments. The last of these, consisting in most cases of an anti-míldio product mixed with an anti-oídio spray, was carried out at the start of the month in the many properties. This was more for safety’s sake than as a result of any widespread or acute threat, and in the majority of cases was restricted to a few localised spots in each quinta that are known for their higher humidity microclimates. For one or two growers they might have been combined with an insecticide against traça (the European grapevine moth) and / or cicadela (a leafhopper) – insects which occasionally start to become perilous at this time of year.

The ongoing drought made irrigation of this year’s new plantings a necessity, and whilst the vines are looking very healthy so far a fair amount of work is required to keep them so. Hand waterings were therefore on the cards for whoever planted had this spring. Once all of these jobs have been completed the labourers are free to take their summer holidays, starting in August. The whole of this month is basically spent just waiting for the grapes to ripen. There may still be time for one or two minor activities before the holidays, however, such as tidying up the pomars (orchards) or track maintenance. It is obviously important that the roads within the quintas have a smooth surface before the vintage starts, and they must be easily transitable before the increased traffic that is brought on by the needs of the harvest arrives.

Share this post