Adaptive actions to support vineyard management using VISCA predictions in Douro Valley, Portugal
- Written by Maha Al-Salehi
VISCA DSS is integrating climate and agricultural models with farmers’ management specifications in order to design short practices, medium- and long-term adaptation strategies to climate change.
In the Douro Valley, where our Portuguese demonstration site is located, the combination of abundant rainfall in March and April of 2020 and a very warm winter influenced the precocity of this year’s growth cycle, with budbreak recorded three weeks earlier than average. These conditions caused recurrent and earlier than expected outbreaks of downy mildew. However, with the predictions supplied by VISCA, the Symington viticulture team was able to plan a very effective treatment schedule, which successfully contained the disease.
Flowering also advanced earlier, arriving two weeks ahead of the regional average, and in order to safeguard good fruit set and ensure a healthy crop, the team at Symington continues to rely on timely VISCA predictions to plan ahead and keep disease pressures at bay.
DSS showing that budbreak has been achieved (May 2020)
Pictures of Ataíde vineyard of first week of May 2020 showing the phenological stage of bloom
During April, VISCA DSS predicted higher rainfall than normal in Douro. This increase of precipitation would risk the spread of grape diseases causing some loss of crops. To avoid this loss, the Viticulturists of Symington have decided to make 4 treatments sprays instead of 3 with an earlier positioning than usual in the calendar, to block the downy mildew cycle.
However in May, it was the hottest May since 1980, the temperature deviation being 3°C, which - combined with lower than average rainfall (half the average monthly precipitation) — has lessened the incidence of disease in the vineyards. Although there has been a diminishing of soil water content, levels are still higher than the usual levels at the same period last year. This condition, combined with VISCA information, support the decision of SYMINGTON viticulturists to delay the deployment of irrigation till end June.
The information of precipitation rate was obtained via the weather information widget of the DSS, and precisely the seasonal & mid-term forecasts:
Other information on irrigation and temperature:
While the information on the temperature shows that models doubted between lower temperatures than normal (40%) vs higher temperatures than normal (36%), somehow similar probabilities. So, the forecast in the sense that it was warned the possibility that temperatures were higher than normal, but with great uncertainty. Under this situation, the growers were able to make the decision to act based on the worst case scenario, which is hotter temperatures than normal.
Several parameters are taken into consideration by VISCA tool besides the phenology cycle, irrigation needs and weather information. These parameters and targets include: Sugar content, Acidity (Ph), Yield (m3), Labour cost (manpower, products, equipment, etc) and Diseases impact.
What would have happened if this forecast had not been available?
Treatments would have been applied later than advisable, reducing their effectiveness by allowing downy mildew to become more established. The consequences would have been the possibility of some crop loss and the necessity to apply more treatments (in April).
Which impacts are expected taken into consideration the predictions of VISCA DSS?
Cost savings resulting from effective pre-emptive as opposed to remedial damage-containment treatments. Also, a potentially healthier crop due to better conditions for flowering and fruit set, and a lower environmental impact.
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