Learning from remote sensing data: a case study in the Trentino region 

Aim: Early leaf removal, generally applied before flowering, is mostly conceived as a technique to control grape yield and improve the health of grapes and focused on the final objective of increasing wine quality.

Wine grapes have the ability to accumulate high amounts of hexoses (glucose and fructose), which is considered one of the main processes occurring during the ripening stage. Sugar accumulation dynamics respond to genetic, environmental and vineyard management factors, with a changing climate leading to advanced and faster sugar accumulation worldwide. Research on mitigation techniques to this phenomenon is ongoing, with the largest focus being vineyard techniques to delay sugar accumulation. Breeding represents another powerful tool to address the issue of high sugar concentration at harvest, since historical trends of selecting best sugar-accumulators may be inverted to breed varieties that accumulate diminished concentrations of hexoses while maintaining optimal acidity, color, mouthfeel and aroma compounds.

The grape variety Gewürztraminer is known to be affected by two physiological disorders namely berry shrivel and bunch stem necrosis. During the season 2014 we noticed a new symptomatology type of ripening disorder on the variety. The new symptom showed not all berries fallowing the normal maturation stages, but single berries remaining at a soft but green stage till harvest. The broad distribution of these so called “green berries” symptoms in different production sites of our region, caused huge damage due to the difficulty of eliminating single berries per bunch before harvesting. Therefore, the Research Centre Laimburg began to investigate the reasons and origins of this new symptom. This work shows the results of first attempts to find causes for the symptom as well as the resulting approach to mitigate symptoms. Applications of magnesium leaf fertilizer showed first promising results against this putative disorder. To study the causal effect of the green berries 30 symptomatic vineyards in 2014 have been selected for a monitoring during the season 2016. To evaluate the foliar nutrient treatment two vineyards have been selected for application of magnesium sulfate and magnesium chloride. Leaf and berry nutrient analysis, as well as the main quality parameters during ripening have been performed. As soon as “green berries” symptoms appeared, incidence and severity have been evaluated. Most of the symptomatic vineyards of the 2016 monitoring showed light to clear magnesium deficit symptoms on their foliage. Only during the seasons 2020 and 2021 “green berries” symptoms could be found in the leaf fertilizer treatment vineyards. Both seasons showed a significant effect of the magnesium treatments to reduce the incidence and severity of the symptom. It seems that the appearance of the “green berries” symptom on Gewürztraminer is correlated to a disturbed uptake of magnesium of the vines.

As a result of climate change consequences, there is a gap between the times at which the grapes reach the phenolic and the technology maturities.

l Veneto, come è noto, rappresenta una delle estensioni di superfici a vigneto più importanti in Italia e nell’Europa stessa. Il paesaggio viticolo fino ad oggi è stato ampiamente letto nelle sue componenti