April 2010 Douro Insider

Good weather had been promised for the Easter weekend but it actually turned out to be a little disappointing; there were still some clouds around and a spot of rain, and in the end the only really sunny day was the Monday.  This ushered in about a week’s worth of basically good conditions with temperatures into the mid-twenties although the clear skies allowed it to cool significantly at night.  By the middle of the month the unsettledness returned, with the wind picking up, sporadic rain and occasional dark skies.  This coincided with another mini tornado, this time in Lisbon, on the 14th.  The damage was restricted to some knocked down walls as well as the usual torn-off rooves and uprooted trees.  The bizarre phenomenon of the mini tornado appears to have become something of a habit in recent months, and sure enough along came yet another one just two days later.  This time it hit Tavira, near the Algarve’s border with Spain, where it casually tossed around 20-odd three tonne yachts with considerable destructive force.  It was the fifth widely-reported mini tornado in Portugal since mid-February.

More bad weather in the Douro followed immediately afterwards, with significant rain falling yet again to disrupt the repairs being carried out on the patamares.  There was also enough precipitation to provide an early risk of primary infections of downy mildew on 15th.  Just as the desiccating effect of dust in the summer helps to protect the vines against fungal diseases, we were hoping for a sprinkling of Icelandic volcanic ash to dry out the vineyards.  But no such luck befell us, and we resorted to more conventional treatments in the end as the skies over Europe fell quiet.

The 21st April brought in a major depression which resulted in another round of furious storms and kept the bombeiros (fire department) very busy, principally due to flooding.  The two epicentres were in the Alentejo, near Beja, and the Mesão Frio / Régua part of the Douro.  The Douro nucleus probably got the worst of it though and, as we have already seen many times this year, the problems caused by torrential rainfall (and hail, in this case) are magnified by steep slopes.  As a result there were a number of floods, sizeable mudslides and yet more rain damage.

Finally the weather began warming up considerably going into the last week of the month, with temperatures reaching into the 30ºs for the first time this year.  There were a couple of thundery moments on the last Wednesday but April finished up quite summery nevertheless.  At this point the mid-row cover crops, particularly the clovers, took advantage of the sudden rise in temperatures to start flowering.  As ever, this was enough to tempt the bees out of their hives en masse, which in turn coincided with the reappearance of the bee-eaters this year, arriving in quite some force.  The ubiquitous Douro poppies were late this spring, however, but the sudden onset of warmer evenings had the nightingales singing until well past my bedtime.

To summarise then, the weather in the Douro this month started cold but warmed up quickly and consistently over the first 10 days, peaking in the high 20s.  Then temperatures dropped but stabilised for about 10 days as the rain hit, before again climbing steeply into the low 30s by about the 28th.  The very last days of the month were a little cooler but with an unsettled feeling in the air and a hint of stickiness.

Total precipitation in Pinhão came to 53 mm, apparently spot on the long-term average.  Rounding down of the decimal place hides the fact that it was actually, by less than 1 mm, the seventh consecutive month of above average rainfall.  Furthermore, as the graph below shows, the cumulative total for this year (currently at 402 mm) is still 50 % above average (267 mm) after four months.  The other chart shows this month’s mean temperature (15.2º C) to be well above average (by nearly 1º) coming after two colder than average months.

In the vineyards the very start of the month saw some farmers still putting on the last of the herbicide applications, but only in the very high altitude vineyards with later budburst.  Talude (bank) clearing was going on too, and some had the trellis repairs still to wrap up.  They were also occasional cases of cane tying for those who finished the pruning relatively late.  In the properties that might be more at risk of being hit by a late frost there is no harm in holding off the pruning for as long as possible to delay budburst.  And since it had been such a cool and unrushed spring so far, others continued replanting falhas (missing vines) this month, or even had the last of the grafting to complete.

One of the first post-budburst operations is always a combination of despampa (removal of non-count shoots) and empara (training the shoots between the wires).  Correct canopy management is essential for keeping the vines free from fungal diseases, amongst other things.  Often the despampa is carried out during the morning when the shoots are colder and more brittle (thus more easily snapped off) and the empara is done after lunch when the shoots are warmer and more pliable.  Access to the vineyards by machinery relies on this procedure being carried out correctly so often it will precede phytosanitary treatments.  Understandably, therefore, it was undertaken all across the Douro during the course of the month.

Early April is almost invariably characterised by the smell of sulphur in the air as the first anti-oídio (powdery mildew) treatment is carried out as a precautionary measure, usually when the shoots reach about 20 cm long.  This year it was not to be, however, because the substantial amount of rain that fell on the 15th coincided with twenty four hours of temperatures in excess of 10º, making primary infections of downy mildew likely.  After all the winter’s rain there is obviously a lot of humidity about and so this will not be a year to take risks with diseases.  As a result we skipped the sulphur and went straight into an anti-míldio (downy) treatment, although with some wettable sulphur mixed in for good measure.  This was, needless to say, carried out in every block.

There is a further vineyard operation that has been increasing in importance in recent years which is also linked to the question of disease management, although we are not yet quite sure how.  The general expansion of the area under cover crops, combined with a wet winter and warm late spring, means that keeping all the inter-row vegetation correctly mown has become something of a problematic new issue.  It has been very difficult over the last couple weeks for the cutting to keep up with the fast growth rate.  Once the topsoil begins to dry out a little it will be more manageable, but for now we have tall grass growing close to the cordon which, without a doubt, is creating humidity in the bunch zone, and therefore must increase the risk of fungal problems.  The clover leaves also attract a heavy dew at night which is sure to exacerbate the problem, and a combination of the height and dampness even contribute to make passage through the vineyards on foot difficult.  It goes without saying therefore that lawn-mowing got underway at many of the quintas, particularly in the Rio Torto area.

Given that April was the first month for what seems like an eternity not to be a complete washout, it should come as no surprise that repairs to the tracks were on the menu yet again.  Many properties therefore had giratórias (diggers) at work.  And on a similar note, repairing collapsed walls in the old vineyards was of course ongoing.  The drier weather meant that mechanical some stone clearing could be attempted – so far this year it has had to be done by removal rather than destruction.  Use of the britadeira (crusher) to smash up stones is not practical whilst the top layer of the soil is muddy; it needs to be reasonably firm to provide some resistance otherwise the hammers simply push the stones into the ground rather than shattering them.  This operation can be carried out in any mechanised vineyard as and when required but will be particularly undertaken in any new plantations.  As such, there is much still to do this spring and summer.

Other than this there was only really one other large scale job going on in the various quintas.  It is not strictly related to viticulture but olive trees are almost as much a part of the scenery as the vines are, and every two or three years they need to be pruned.  By this stage it is getting a little late, and it is therefore coming to an end for this year.