The month got off to a good start with a wonderfully summery first day, producing some remarkable temperatures that were to set the tone for the rest of April. It stayed hot for most of the first week, with the mercury touching on the low 30ºs, and it felt even hotter as a result of the high humidity. The skies were also hazy for several days around this time, giving the unwelcome impression of those sultry August days when the air is darkened by smoke from catastrophic wildfires. In fact the phenomenon turned out to have been caused by some sort of rogue dust cloud with its origins in a north African sandstorm.
On the domestic front April was immediately marked by sudden decrease in consumption of firewood, and a corresponding increase in production of ice cubes as something cool and refreshing became essential after work. By the second week of the month the hot weather had brought back the bee-eaters from their winter migration, and the vines predictably made very rapid progress. Then, after just over three weeks without a drop of rain, the weather started to change in the run-up to the Easter weekend, which itself turned out to be pretty nasty and very wet. Obviously this meant that as soon as the four-day weekend was over, and we had to go back to work, everything perked up again and it was sunny and hot once more.
We needed this second spell of good weather for treating the vines as the week prior to Easter had provided perfect conditions for primary infections of downy mildew, and at the same time the humidity and warm temperatures encouraged powdery mildew too. The month then basically went on again as it had started – hot and hazy, still and dry and with plenty of sun. Only in the final two days did it change once more, with masses of rain. In the Benfica area of Lisbon there was a dramatic hailstorm on the afternoon of the 29th which dropped enough ice to close some of the roads, and then it quickly melted leading to severe localised flooding.
Climatic details from the various quintas predictably showed it to have been way hotter than a typical April, with the average temperature in Pinhão, at 17.7º C, some three and a half degrees above the long-term mean. This made it the second hottest April on record, but it still came in quite a way behind the 18.3º from 1997. Monthly maximum temperatures were in excess of 30º at most properties, peaking at over 33º at some locations.
Precipitation was unremarkable across most of the Douro but, as ever, displayed considerable spatial variation. Rainfall in Pinhão, at 42 mm, was just below average, making it the fourth consecutive month that was drier than might be expected. The cumulative total for the current year now stands at just 209 mm, which is some way under the average value for this stage (267 mm).
It is interesting to note that in spite of the common impression that we had endured a rather damp winter, actual precipitation has been below average for five out of the last six months. Only December’s huge total has ensured that the soil water level is still comfortable for the vines, but that came along well before budburst. Furthermore, the hot weather means that vine water consumption is higher than usual, so we would definitely benefit from some decent rainfall in May. Obviously not much can be expected from June onwards.
We started the month in the vineyards finishing off a couple of jobs that had hung over from the end of March. Some quintas were still replanting americanos as April got underway (although by now it was getting just slightly late) and others found that the grafting still had a week or two to go. Weed control was another worry; in spite of the dry weather it was quite clear that there was no lack of water in the topsoil and there was plenty of plant growth in places that we didn’t really want it. On the other hand, it also meant that the Douro’s spectacular wild flowers put on a great display. The general movement away from the use of herbicides has greatly benefitted the aesthetics of the region, and biodiversity is clearly on the increase. It did mean, however, that we had our work cut out with manual weed clearing, especially on the banks between the terraces.
April is normally a very busy month, and a hot April is even busier than usual since things can happen very quickly indeed in the vineyards. Growth was really very fast, and it soon became clear that the phenological cycle was getting well ahead of its normal rhythm. This meant that we had something of a race on our hands to keep work up to date in the quintas. At this stage of the spring, canopy management is the key to successful viticulture. The first phase is called despampa, which is best described as a combination of de-suckering and shoot-thinning. Basically it involves the removal of all shoots on the vine sprouting from what we call non-count nodes. In other words, we would like one shoot to grow from each bud that was left during the winter pruning. Other shoots that might have burst from the trunk, or from base-buds, are gently snapped off with the fingers. This is a way of controlling yields and also ensuring that the canopy is not too dense. Too much foliage will reduce the effectiveness of anti-fungal treatments as the spray is unable to penetrate into the middle of the canopy.
Next up, or sometimes simultaneously, we have empara – or shoot positioning. This involves guiding the growing shoots between the pairs of foliage wires so we are left with a nice tidy and vertically orientated canopy. Only with the shoots correctly trained up and away from the inter-row space can we pass through the vineyards with a tractor. Otherwise much damage would ensue, not to mention potential loss of crop. One factor initially working in our favour this spring was the fact that, at least towards the beginning of the cycle, there was not a huge risk of fungal diseases. Nevertheless, we always like to put a good dose of sulphur onto the vines early in the season, more as a precaution than anything else, and so a quick round was done during the first week or two.
The rain that came just before Easter provided the first real challenge from the point of view of fungal diseases, with conditions clearly propitious for an outbreak of downy mildew. A serious attack can wipe out an entire year’s crop even before flowering has happened so it is clearly a serious matter, and we wasted no time in spraying immediately after the holidays so the vines were fully protected by the time the primary infection emerged.
The only other activity of note was going on in the new plantations, where the contractors had by now finished planting the young rootlings. The next job is usually putting up the trellis, so they were kept busy installing posts and wires. Although the vines will not be trained up the trellis this year, the payment of subsidies for new plantations does demand that the vineyard is completely trellised as obviously this makes up a significant part of the expense. It is better to put the posts up early on so we can then begin to dig the watering depressions for each vine – that way they will not be disturbed by the passage of machinery through the new vineyard. We won’t need to water for another month or two but it pays to be prepared.