June 2009 Douro Insider

The very start of June was blessed by a continuation of the hot and sunny weather we had been enjoying beforehand, but by the first weekend a series of cyclones in the north Atlantic had already started rolling into Iberia, bringing with them a cold front of unsettled weather. It immediately turned a little sticky, with thundery conditions and moderate rain. This weather system hit the UK at the same time, although there it involved much more precipitation. Torrential rain caused flash flooding in Devon and South Wales but over here we still didn’t generally get anywhere near enough to even begin to recover this season’s negative water balance; according to official sources at the Instituto de Meteorologia the month had started with 66 % of continental Portugal in a state of ‘severe and extreme drought’.

Even after the main storm front had passed over, the not-very-good weather continued into the second week of the month, at least in the north of the country, and there was plenty of rain over the feriados (holidays). Those who had escaped south for the extra-long weekend, however, enjoyed hot, sunny and typically summery conditions. As can often be the case in June, there was little stability in the weather patterns. The third week was very hot and humid and at times the sky turned extremely dark and thundery. Unfortunately no rain was forthcoming in spite of this, but we did get a scorching weekend in the city where the humidity always seems to exaggerate the heat.

The greatest of Porto’s annual festivals, S. João, is carefully timed to coincide with the worst weather of the summer every year. Thus it was no surprise that round about the 24th it became unsettled once again, with much colder temperatures being felt and overcast skies. Mercifully the thunderstorms forecast for the barco rabelo regatta didn’t turn up but it was rather grey, and things continued more or less in this vein for the rest of the month, with scattered showers falling on the coastal regions, and making their way inland to the Douro a few days later. We thus saw out June with all sorts of weather: windy, cloudy, sunny, wet and dry spells fluctuating capriciously between each other. All this was accompanied by uncharacteristically high relative humidity, and curiously it was even more the case in the Douro than on the coast. It was an incredibly sticky end to an unusual and rather unpleasant summer month.

Records from Pinhão showed a range of absolute temperatures running from 13.0º C all the way up to 37.6º, and averaging out comfortably above room temperature with a monthly mean of 22.7º. The relatively balmy absolute minimum was the warmest experienced in the quintas, so there was no need to feel cold at night. There were seven days hotter than 35º, and most nights the minimum stayed pleasantly between 15º and 20º. The long-term mean for June is one degree cooler than this year’s figure, at 21.7º, so it was actually a comparatively hot month (even though it didn’t always feel like it – there was one day in the first week on which the maximum temperature didn’t even make it up to 20º).

In terms of rainfall we were actually fractionally above the average (33 mm) with 40 mm, although in all honesty the unsettled weather could easily have brought a lot more rain had we been luckier. That said, it was wetter than March, April and May so perhaps we should be grateful for small blessings.

The temperature graph appears to indicate that the year is very close to average in terms of temperatures, with three hotter months and three cooler months relative to the mean. The same cannot be said about precipitation, however. The usual graph shows as that this was the first month since January with (only just) above-average rainfall. And, amazingly, it is only the second such month in more than a year, since the very wet April of 2008. For once the gap between the two lines closes slightly, although of course 7 mm is clearly not much ground made up. Our running total now stands at just under 280 mm, whereas we would normally have hoped for more nearly 360 mm by now. Almost all of the rainfall came within a couple of days of the first weekend.

June normally introduces only one new activity into the viticultural year’s roster; the rest of the work in the vineyards being a continuation of the various procedures that have been going on during the course of the growing season. It is usually the month in which the first round of desponta, or shoot trimming, gets underway. Trimming can be carried out mechanically, or by hand using pruning secateurs. The objectives of the operation are fourfold: firstly, they make the vineyards physically more accessible, both on foot and for machinery. Left unchecked, vigorous growth often leads to the shoots from opposite vines meeting each other across the mid-row space. This makes any other type of work extremely difficult. There is therefore also a certain aesthetic appeal to the practice. Secondly, it improves the penetration of any spraying that might be required, ensuring that the product reaches both the bunches and the more humid inner foliage where fungal problems are most severe.

The third reason is related: by airing the vegetation the microclimate inside the canopy is altered, making sure that any dampness (e.g. from rain) will evaporate quickly. At the same time, early exposure of the grapes to the relatively weaker sun means that they are less likely to suffer from sunburn in the future. And finally the removal of the growing tips of the shoots will stimulate the growth of laterals. It is precisely these new leaves that will be mature carbohydrate producers during the main phase of grape maturation – they are responsible for much of the future sugar accumulation that will be so important come harvest time.

As we have seen, most of the other operations have already featured strongly so far during the spring. Empara (positioning shoots between the wires) is a closely related practice, and continued fairly much everywhere. Also related, although now falling from favour due to a combination of mechanisation and modern trellising systems, is the old-fashioned enrola, which involves winding the tops of the shoots in a spiral along the top wire. By laying down a shoot horizontally we vastly reduce the effect of geotropism and practically stop its growth. There was also, still, some despampa required but only at quintas in areas with high rainfall and the resulting tendency towards excessive vigour.

In terms of anti-fungal treatments there was fortunately not a huge disease pressure, but the humidity made powdery mildew an ever present danger. Downy has not been seen at all this year (so far, at least) due to carefully-timed preventative spraying. Given the time that it might take to cover a large property, prevention is always the safest philosophy. There were some spot herbicide treatments still required, although one wonders how the weeds seem to appear when the soils are so dry. Ploughing also has the same effect, keeping the vineyards tidy-looking, but on the terraces talude-clearing has to be carried out by hand. It is also a good time of the year (if, of course, the labourers can be freed up from the work in the vineyards for a day or two) to take a look at the olive groves. Weed clearing there is important too, for aesthetic as well as practical reasons. As we mentioned in an earlier report, much of this is now being done by mechanical mowing.

The only other procedures of any note are confined to quintas which have planted new vineyards in 2009. Although hardy, first-year vines obviously have considerably less capacity to extract water from the soil than adult vines since their root systems are both shallower and much, much less extensive. The non-vinifera ‘American’ rootstocks can and indeed do survive their first year without irrigation but ready-grafted rootlings are not designed to be abandoned to the Douro summer. Thus irrigation of the new plantings was again on the cards. As usual, caldeiras must be all present and correct, and the critical business of keeping the vines alive depends almost entirely on making sure they do not go thirsty.