April 2009 Douro Insider

April got off to a relatively cool but sunny start although things turned grey at the beginning of the second week. There were some showers on the coast which were reflected in a small amount of inland rainfall but mainly this change in the weather brought an increase in windiness to the Douro region. They were not always the usual westerly winds that characteristically blow upriver on a summer evening, however, and there was some vento soão thrown into the mixture too. This easterly wind that comes in over the continent is not generally popular as the air tends to be very dry and dehydrating for the plants. On the other hand, the lack of humidity makes the development of fungal diseases very difficult and therefore it can be helpful for the viticulturist. It is not known as sulfato espanhol (Spanish fungicide) for nothing. The sad fact of the matter is that we didn’t need the wind at all; we needed rain. Remarkably, there were 26 consecutive dry days in March, plus a further eight in April, before it finally rained in Pinhão, making this one of the driest springs in memory.

Poppy day was about the 10th April this year, when the flowers suddenly burst into bloom simultaneously all across the region. They met with pretty unpleasant conditions, however, as things were unsettled to say the least around the Easter holiday. The Serra de Estrela mountains, in the centre of Portugal, were cut off once again due to heavy snow falls, there was some very aggressive sleet and even moments of hail in Porto after the long weekend, and all of this stormy weather had quite reasonable penetration inland. There were gusting winds and one or two short but torrential rainstorms in the Douro. It would then turn suddenly sunny (and a little sticky) and temperatures seemed to fluctuate back and forth between hot and cold several times during the same day.

There were occasional spells of all-night drizzle but not enough of them. Slow rainfall is obviously much more useful as run-off is minimal and the water penetrates deeper into the soil. The middle of the month was definitely the wettest part and brought welcome relief for allergy sufferers, stripping some of the spring pollen out of the air. The vines are still a long way short of flowering at this point but the clovers in the cover crops came into bloom and we had to mow them for the first time. At about this stage (and it is certainly not a coincidence) the bee-eaters returned from their winter sojourn, chirping cheerfully as ever. They seem to congregate particularly around the flowering eucalyptus – presumably because it attracts plenty of bees – and their iridescent flashes circle around until it is almost dark. Whilst on the subject, there has been a clearly noticeable decrease in the bee population this year, as seems to have been the case in many countries. One hopes that a solution for colony collapse disorder can be found rapidly since a shortage of bees would have extremely serious repercussions for other parts of the ecosystem, including both the aforementioned bee-eaters and the clovers, not to mention a vast range of food crops.

The upshot of all this was that we ended up with yet another dry month, with the total rainfall in Pinhão just 38 mm, a figure well short of the average of 53 mm. According to the Instituto de Meteorologia, 16 % of Portugal’s continental land area is now undergoing ‘severe drought’, a frightening statistic for the end of winter. We would do well to remember that it was this month last year that quite possibly saved the entire harvest, with nearly 150 mm of rain. Where this leaves us for the rest of the year is anybody’s guess, but the prognostics are not particularly sunny if it gets sunny, so to speak.

The graph below, illustrating the cumulative total precipitation, confirms what we already suspected. Even ignoring the fact that we started the year on a serious water deficit from 2008, the temporary bonus that January’s rainfall provided has now been eroded away and we are starting to accumulate something of a shortfall again. Whilst we have had a reasonable 227 mm of rain so far for this calendar year (the average for this stage is about 270 mm), more worrying still is that we have now passed the first (and by far the wettest) half of the agricultural year with only 349 mm to show for it. Given an annual average of about 675 mm, we should be up around the 440 mm mark by now, a deficit of 90 mm in real terms.

After March’s apparent break with recent patterns (in so much as that it was relatively warm) we seem to be reverting to type, with yet another month of below average temperatures. In this overheating world we have actually been lucky enough to have enjoyed a prolonged cool spell. This was the 10th colder-than-average month out of the last 12, the two exceptions being March of this year and June of 2008. The average monthly temperature over the course of the last year has been nearly one degree cooler than expected. We are told that this is because the surface water temperatures in the Atlantic have been cooler than usual in recent months which has a tendency to calm and stabilise weather patterns.

In Pinhão the coldest temperature of the month, a not unbearably cold 4.0º C, came on the very first night but it wasn’t until we were getting on for the last week that the highest value was recorded, 29.3º. This final flourish of sunshine was not enough to boost the average temperature by much, which at 13.3º was well below the long-term value of 14.4º. We have to go back to the year 2000 to find the last April that was cooler.

After a predictably quick start to the phenological cycle caused by last month’s heat, this cold weather slowed down considerably the development of vines. The very fast shoot growth that immediately followed budburst suddenly appeared to have been suspended almost completely, giving us a chance to catch up with the empara (about which more later). The growth rate picked up again when the cold spell had passed and conditions warmed up a bit at the end of the month, and this heat was enough to entice the snakes out of hibernation for their first forays of the year, although it only really got hot from the end of the third week.

At this stage in the viticultural cycle there are two major activities that take up the lion’s share of the work in the vineyards. Firstly the expanding foliage must be controlled, as otherwise both the quality of the fruit and the health of the plant might be compromised. This involves the removal of some unwanted shoots, and the correct orientation of the remaining majority. The unwanted shoots generally consist of all those that have not burst from one of the count buds left during the winter’s pruning, and also of suckers shooting from the trunk of the vine, below the fruiting wire. Occasionally one or other may be left for the purposes of retraining part of the vine, or replacing a pruning spur, but usually they are removed to maintain vine balance since they are not normally fruitful. The green training of the canopy (shoot positioning) involves tucking the growing shoots between the successive pairs of foliage wires as they reach their respective heights. On many occasions these two procedures (despampa and empara) are carried out on the same day – despampa (which refers to both shoot thinning and desuckering) works best during the mornings as the colder shoots snap off more easily, and come the afternoon we tend to change to empara (shoot positioning) as the warmer shoots are less likely to break whilst being manipulated into position.

It is worth noting that there was still some last-minute trellis maintenance being carried out at many of the properties. Repairing and tightening broken or slack wires, replacing missing staples and so on obviously needs to be done before the shoots reach the level of the wires to avoid damage to the plants.

The second major operation is of course protecting our vines against diseases, and to this end there was a general application of sulphur carried out across the region. So far climatic conditions have not suggested any significant risk of míldio (downy mildew) so we have only really been concerned with oídio (powdery mildew) and even then the risk is minimal, given the clear skies. In many respects it would be nice to have to worry about míldio as at least that would mean it had rained somewhat. In spite of the drought there was also some fairly widespread weed control going on, with ploughing, talude maintenance and herbicide applications all being carried out at one or other of the quintas. Even the cover crops needed mowing back as they had started to come into flower. The first cut is normally done at about this point, since if they are allowed to finish flowering the plants will have completed their cycle, and thus dry up. By removing the first flush of flowers we can set them back by a few weeks and maintain the ground cover a little longer.

Other activities were rather piecemeal (such as sporadic fertilisations) but there was still much going on related to the new (and re-) plantings. Most properties still had to finish the annual spell of grafting, and not all the new vineyards were completely planted until mid-month, although this is by no means considered late. Those that had been planted still needed stones to be cleared or broken, caldeiras to be dug and even the first irrigations by hand of the young vines. Where considered appropriate, grow-guards were also being installed on the first or second year vines. It is hoped that these will help them cope with the dry conditions in what is turning out to be an exceptional year.