Viticulture Bulletin – Spring 2023

Synopsis

This bulletin covers the spring of the 2022-2023 viticultural year, although we’ve only included the period from April to June because March was included in the previous (Winter) bulletin. Whilst April was exceptionally dry and unseasonably hot in the Douro (following on from a very dry and warm March), May and June brought respite in the form of near average rainfall in May and well above average rainfall in June. Temperatures for the two months were, in the main, above average although not excessively so, and the absence of intense heatwaves (common in recent years over this period) was another positive aspect.

The Portuguese met office reported the third driest month of April since 1931. In the Douro, the month was extremely dry, ranging from just 3.2mm of rainfall at Vesúvio (8% of the average rain for the month) and 11.2mm at Cavadinha (one fifth of the average). To compound the situation, temperatures were unseasonably high, 3.2°C higher than average at Cavadinha. Soil water content (as measured at Bomfim) continued to tumble. At the end of April it was 22.7%, a drop of 5% in just one month. At the end of April, 89% of Portugal was under drought, with most of the Douro region (and Portalegre) classified as being under ‘moderate drought’. Only the northwest of Portugal (Minho and Douro Litoral) was classified as ‘normal’.

Although May started very dry, prolonging the three-month period of near unbroken drought, and raising some cause for concern, we were relieved to see the arrival of abundant rainfall, even though concentrated in the last week of the month. Some of this came in the form of thunder and hailstorms but fortunately our vineyards were not negatively impacted, even though in some instances there was apprehension. On the 28th, for example, 22mm fell at Malvedos, half of which in just 15 minutes! Interestingly, contrary to what we would expect, higher rates of rainfall were recorded in the Douro Superior than in the Cima Corgo. Ataíde and Vale Coelho had, respectively, 21% and 43% more rain than normal, whilst Cavadinha and Tapadinha (usually among our wettest quintas) had 35% and 17% less rain. Temperatures for the month were above the 30-year average in practically all our quintas, but not unduly so and the generous rainfall largely mitigated the effect of the heat.

The wet period continued into the first half of June in the form of tropical storm ‘Oscar’ which came in from the Atlantic bringing waves of heavy rainfall between the 3rd and the 10th. Between these dates more rain fell at Bomfim than normally falls during the whole month (41.2mm compared to the 30-year average for the property: 27.7mm). Across the globe, many countries were reporting the hottest month of June on record (including many parts of northern Europe) although, unusually, temperatures in Portugal did not reach the extremes of the last few years. In fact, in the Douro the temperature deviations were less pronounced than in other parts of Portugal.

For the viticultural year thus far (i.e., from November 2022 to June 2023), and taking Bomfim as our reference point, we have more cumulative rainfall than the 30-year average, even if only just — 563mm compared with 545.3mm. In sharp contrast to this, the position this time last year was much more unfavourable with a 70% shortfall in cumulative rainfall for the comparable period.

Flowering and fruit set: We registered the earliest flowering since we began to methodically track the phenology in our vineyards, more than 20 years ago. A combination of the wet winter and unseasonably warm spring created conditions for the very precocious flowering we recorded in our quintas — at Bomfim on May 3rd (a week earlier than in 2022), and at Ataíde on May 2nd (11 days earlier than in 2022). This was one of the shortest intervals we have seen between budbreak and flowering, in some cases just 5 weeks! Fruit set progressed well and barring any significant climatic events, we could be on track for a good-sized crop.

Soil water content: soil water readings taken during June from the probes at Bomfim, mirror the month’s weather pattern with an increased water availability during the first half of the month, and then dropping sharply during the second half. At the end of June, soil water content stood at 16.7%, which is just above the threshold of the ‘Readily Available Water’ index (RAW) - i.e., water in the soil that the vines can actually tap and use. This compares with13.5% at the end of June last year, a figure below the RAW index. We are therefore in a
marginally better situation this year.

Alentejo

Even more so than the Douro, April was exceptionally hot in Portalegre, 5.1°C above the monthly average. This was not helped by the very low rainfall, just 10% of the average for the month. May was also hotter than usual although not to the same extent as April and rainfall was only half of what we would expect in a normal year. The very hot conditions continued in June but at least the rain was closer to the monthly average.

Fernando Alves, Miguel Potes and Joana Valente · July 13th, 2023

Picture taken at Prats + Symington's Quinta de Roriz.