November 2008 Douro Insider

November got off to a very grey start and, although the air was decidedly damp, nothing of any consequence in the way of rain was forthcoming.  Thick, wet and very clingy fog hung in the lower-lying areas.  To begin with, at least, it appeared not to be too cold, but towards the middle of the month the mornings chilled down considerably, especially for those right in the thick of the murk at the bottom of the valley.  Then as the foggy spell finally lifted the insulating effect of the blanket of low-lying clouds was no longer felt.  The skies cleared, and with this came an increase in of the range of daily temperatures: when the days were clear sunshine warmed up the earth pleasantly (albeit briefly) but the nights were distinctly icy as there was no cover to prevent this meagre heat from being radiated back into the night sky.  Thus began a downward turn, and winter started to take hold.

Going into the last week of the month much of Britain was blanketed heavily with unseasonably early snow.  The effects of this Western European cold snap were felt here too, with ice forming on the windscreen at night in many parts of the region for the very first time this year.  Indeed, negative temperatures were registered in all of the quintas this month, but a few days later things got even worse.  There were periods of sleet, hailstorms and even frosts in Porto and the last weekend of the month actually brought the first snow falls to some areas of the country.

Although it was definitely cold up the river in the Douro, it is still perhaps something of a surprise to note that readings in Pinhão confirmed that it was indeed the coldest November since our records began over 40 years ago.  To put this in context, the average temperature for the month is around 11.6º C, and 2008 brought us a mean value a full two and a half degrees lower, at just 9.1º.  That said, there were only three days below zero, and still two just scraping in above 20º (peaking at 20.6º).  The lower limit came in at -1.4º.  We have now had five consecutive months of below average temperatures, and yet another (this time the seventh in a row) with less rainfall than usual.  With just 37 mm of precipitation falling (of which the vast majority came over only two days in the last week of the month) we received well below half of the average, which stands at 87 mm.

Looking at the precipitation graph below, the wide separation between the red and orange lines shows that we are now running at a deficit of over 130 mm.  Plenty of winter precipitation is therefore absolutely critical as it is clear that the water tables are seriously depleted and if the Douro is not extremely well-watered over the next few months the implications for both yields and the quality of the grapes for the 2009 harvest could be very severe.

The phenology of the vines was a little unusual this autumn, and completes an interesting year in the vineyards.  To resume briefly, the vegetative cycle in 2008 was very long.  It got off to an early start, and leaf-fall was surprisingly late, and all this in a year of very little water.  In spite of the drought, vigour was high and there were no dry leaves on the vines during the summer.  The cool temperatures this year have left the vineyards in remarkably good health and it seemed as if they didn’t want to stop working for the winter.  The fact that there were no frosts until right at the end of November also helped the leaves to hang on for longer, as well as considerable amounts of copper sulphate that were applied during the spring to combat fungal diseases.  Copper strengthens the canes and delays vegetative senescence.

The autumn colours were extremely intense compared with some years when the green just dries straight to a nondescript brown, and the exact shade the leaves turn depends on the variety.  Touriga Nacional tends towards a slightly sickly yellow, whereas the tintureiras (varieties famed for the colour they give to a wine) turn dark purple and the Touriga Francesa provides perhaps the most spectacular oranges and reds.

Work in the quintas is often quite limited in its scope at this time of year since November normally marks the start of pruning.  This is, of course, the single largest undertaking in the viticultural year.  Given the long period of dormancy, the timeframe is more relaxed than for most jobs, and therefore it is frequently accompanied by other activities.  At many properties olive picking also got underway.  Ripening was very early this year with the colour of the olives starting to change back in October.  Yields look pleasingly high so far but considerable fly-damage has been sustained which will unfortunately oxidise the fruit, increase the acidity and decrease the overall quality of the oil.

In the vineyards, as we have said, pruning was being undertaken everywhere.  In order to save time it is commonly preceded by pre-pruning.  This operation involves cutting away most of each cane (which may or may not be shredded simultaneously) and removing the cut part from the trellis wires.  When the pruners pass through the vineyards afterwards it is therefore much quicker and easier to see where to cut.  There are three main ways in which pre-pruning can be done: manually, semi-mechanically and mechanically.  Manual pre-pruning is done with normal pruning secateurs and is the best way of ensuring that all of the canes are removed from the wires as individual tendrils can be cut or broken if necessary.  It also means that no canes are accidentally cut on young vines which would be better left for training onto the wire to create the cordons.

Semi-mechanical pre-pruning is done using hedge-trimmers cutting a few centimetres above the fruiting wire.  It is very quick (walking pace) and can obviously be selective as well.  Mechanical pre-pruners mounted on the tractor are quick and efficient but indiscriminate, and they also suffer from the considerable drawback that they often damage the trellises.  Where the trellis posts are made out of brittle schist, mechanical pre-pruners are out of the question as the number of broken posts that will need to be replaced outweighs any benefit they bring.  Even with wooden posts the trellis wires need to be kept taut to avoid damage.  Otherwise even a relatively small rock under the tracks can cause the tractors to see-saw, altering the angle of the cutting blades away from the horizontal.  Loose wires can be snagged at this point and cut or ripped out.  For this reason trellis maintenance (e.g.  tensioning wires) is sometimes carried out before pruning as well as afterwards.

Where possible pruning and (especially) pre-pruning should start in the Tinta Roriz as it loses its leaves relatively early and, apart from anything else, the canes are more brittle than most varieties, cutting easily.  After pruning the canes must be dealt with, either shredded mechanically or collected up and burnt.  This last option is the only one in old vineyards where tractors cannot enter.  Thus cane destruction was also underway at many of the properties, although normally it starts a little later on when pruning is closer to completion.  On the other hand, once the mechanical pre-pruner has finished its work there is a tractor and tractor driver available to get started with this side of the operation.

Other activities going on during the month include ploughing, which may be undertaken for weed control but is also necessary before sowing the cover crops in the vertical plantings.  These mixtures of leguminous species (e.g.  clovers) and gramineous species (such as ryegrass) not only stabilise the soil during the winter rains, massively reducing erosion, but can also be used to increase organic matter in the topsoil.  Taludes (the steeply sloping banks that support each terrace) were cleared of vegetation in places where it had sprung up, and stone removal can occur anywhere whenever there is a quiet moment.

This last one is a job that has almost unlimited scope in the Douro but is not often a main priority.  In many cases stone clearing is tied in with the whole surriba process.  This is an operation that is carried out before planting (or replanting) a new vineyard and involves physically turning over the top metre or so of soil using bulldozers.  The rather labour-intensive process removes some of the buried rock or at least breaks up the worst of the stones so that the young vines are better able to root.  Terrain preparation for the 2009 new plantations has now started across the region.  In some of the quintas old vineyards (vines, wires, trellis posts and so on) need to be removed by hand before the machines can move in and start the surriba.  By late winter or early spring the ground must be ready to plant.