What actually happened in February is very easy to describe. Why it occurred, and what the consequences will be, is very much more complicated. So what did happen then? Basically, nothing. There was no wind. There were no clouds. There was certainly no rain. It warmed up nicely during the day under sapphire skies, but then it got very cold indeed at night. Portugal, along with much of the rest of Europe, was held in the grip of a very stable cool spell for several weeks. The lengthening days permitted quite warm maximum temperatures on occasions but the nights were bitter.
The absolute range of temperatures was therefore huge – with almost 30º C between the hottest and coldest recorded values at some quintas. But the cold easily outweighed the warm, and the month came in well below average on balance.
We awoke on the first of the month to plentiful warnings in the media that the frozen spell being endured to the north and east of us was on its way over here. An anticyclone planted over central Europe dragged in a mass of very cold and dry air which literally chilled the entire continent. Negative temperatures in parts of the country dropped into double figures as this icy system wafted in gently from the northeast. Frosts were obviously widespread. There was temporary respite near the start of the second week, but only for a day or two, and the Scandinavian cold was back again in much the same way due to another series of high pressure systems. Indeed, the slight warming interval between the two cold spells was so shortlived that nobody really noticed it anyway.
The Douro was particularly badly affected the second time, with some of the lowest temperatures in Portugal registered around here: -10.2º in Miranda do Douro, for instance, and -9.5º in Carrazeda de Ansiães. This was nothing compared with more northerly parts of Europe, however, where the balance of the month left around 500 dead as a direct result of the cold. Even way out here on the periphery there was an easily detectable increase in national mortality rates too. The anticyclone eventually began to weaken in the last week of the month and, coupled with a distinct lengthening of the evenings, temperatures immediately picked up. It finally felt pleasantly warm on occasions, especially towards the end of the afternoon, and the mercury climbed into the 20ºs for the first time this year. The good news was that the fog quit at long last, but that also meant that the frosts kept on coming at night. There was a definite widening in the absolute range of temperatures as a result.
It might seem ridiculous mentioning this aside in February, but the forest fire season got off to a worryingly early start this year: it kicked off with a big blaze on the 23rd in the Serra de Estrela, then a few days later another major conflagration burned for a couple of days near Braga. Parts of the country were put on maximum fire alert due to the desperately dry vegetation. By the end of the month, 68 % of Portugal was in a state of severe drought. The remaining 32 % was undergoing extreme drought – the highest category on the scale.
Unsurprisingly the climatic data reveals a month that was much colder than average – by a huge 2.5º. Indeed, with a monthly mean of just 7.2º in Pinhão it was colder than the average January too. As was mentioned earlier, February also delivered far more polarized temperatures than January did, with higher monthly maximums and colder minimums. This has been the third consecutive month of below average temperatures, meaning that on the basis of December, January and February’s figures this has been the coldest winter since 1991.
Precipitation this month was absolutely zero, the first time in February since 1997, meaning that our cumulative graph has been flat-lining since the start of the year (see that yellow line right at the bottom?). The total, at an inconsequential 9 mm, is just one eighteenth of the average value for this time of year (163 mm) and November itself was the only month in the last 14 to provide significantly above average rainfall. The total winter rainfall (December to February) was just 47 mm when the average for this period is almost 250 mm. In other words, precipitation this winter has been less than a fifth of the expected amount. Perhaps surprisingly this is only actually the second driest winter since the since start of our records in 1967: the same period over 2004 / 5 provided a mere 44 mm. It is particularly frightening that long-term forecasts for March are for yet another month of below average rainfall, and of course the associated intensification of the drought.
Humidity data from a soil probe at one of the Douro quintas reveals that current soil moisture levels are extremely low. It is enormously worrying to have to relate that the amount of water in the soil at the end of February this year was less than it was at the end of July 2007, and also July 2010. How exactly the vines will cope with so little water is hard to predict, but it is no exaggeration to say that we are in uncharted waters. Or perhaps uncharted deserts. No doubt all will soon be revealed: the sudden upward turn in the soil temperature during the second half of the month will have stimulated the first flush of root growth this year, meaning that budburst is not far behind.
In last month’s report some detail was given about the grafting process, but not about actually planting the American (non-vinifera) rootstock itself. This is by far the dominant activity in the vineyards in February, however, with most of the month given over to replanting falhas. This procedure, to replace ‘missing’ vines (any plants which died over the course of the last year for whatever reason) is concentrated in two main areas. The first, obviously, is in the vinhas velhas – the old mixed (and unmechanised) vineyards. Every year a small percentage of the vines simply expires from old age. These vines are easily identified during pruning because all their canes will have dried out and lost the green core of living tissue. So as not to leave gaps in the vineyard the dead vine is pulled out and a new rootstock planted in its place.
The other main area where replanting is required is in last year’s new vineyards. No matter how carefully the vines are looked after over the first year, or how many times they are watered, it is impossible to achieve a 100 % take rate. Unfortunately what seems to have happened this year is that a number of the 2011 rootlings actually made it through the summer fine but, sometime between leaf fall and pruning, gave up the ghost during dormancy. This is unusual to say the least and the only plausible explanation must be that the tender young roots were simply desiccated over the winter by the bone dry topsoil.
To some degree we left the replanting a little late this year – holding on to see if it rained a few drops before we just had to bite the bullet and get on with it. It didn’t rain, obviously, and as a consequence it was particularly difficult to plant the americanos with the ground rock hard. The plants then had to be watered in of course (something that we have never needed to do in the past) and if things continue in the same vein we will be watering the rootstocks again during the spring and summer. The real advantage of using rootstocks rather than bench grafts for replacing falhas is that they are much hardier: under normal circumstances it is just a case of sticking them in the ground and forgetting about them. Circumstances this year are far from normal and it is clear that even the americanos will need special care over the next months. Whilst all this was going on, the grafting of last year’s americanos continued.
Once all this is out of the way there is little pressing that needs to be tackled until the end of the month when it becomes advisable to turn one’s attention to pre-budburst weed control. Given the cold that we have suffered over the last couple of months (and the drought) it is likely that budburst will be quite a bit later than usual this year so the pressure is off for a while. Some quintas took the time to trim back the almond trees in much the same way that we pruned the olive trees in January. Fortunately the inverted cone pruning technique is just as applicable in amygdaliculure as it is in oliviculture so there are no new skills to be learned. As with budburst on the vines, the almond trees come into blossom later on when the winter is cold – a natural protection against surprise spring frosts. The first white flowers this year started to emerge right at the end of the month, suggesting that budburst will be along about three weeks later. In other words, we are looking at a late start to the cycle this year in all probability.