Application of Hyper Spectral Imaging for early detection of rachis browning in table grapes

A solid feature of climate change is that the frequency and severity of weather extremes are increasing. Ranking European countries for the number of crop failures related to extreme events reports France on top followed by Italy and Spain (COM 2021).

Odours deemed harmful by the consumer and described as “stable”, “horse sweat” or “burnt plastic” can be found in wines. The responsible molecules are volatile phenols, produced by a spoilage yeast: brettanomyces bruxellensis. This species is particularly well adapted to the wine environment and can resists many stresses such as a high alcohol level, a low ph or high levels of SO2, more or less efficiently depending on the strain considered.

In viticulture, the challenges of local climate modelling are multiple: taking into account the local environment, fine temporal and spatial scales, reliable time series of climate data, ease of implementation and reproducibility of the method. At the local scale, recent studies have demonstrated the contribution of spatialization methods for ground-based climate observation data considering topographic factors such as altitude, slope, aspect, and geographic coordinates (Le Roux et al, 2017; De Rességuier et al, 2020). However, these studies have shown questions in terms of the reproducibility and sustainability of this type of climate study. In this context, we evaluated the potential of MODIS thermal satellite images validated with ground-based climate data (Morin et al, 2020). Previous studies have been encouraging, but questions remain to be explored at the regional scale, particularly in the dynamics of the massive use of bioclimatic indices to classify the climate of wine regions. The results at the local scale were encouraging, but this approach was tested in the current study at the regional scale. Several objectives were set: 1) to evaluate the downscaling method for land surface temperature time series, 2) to identify regional thermal structure variations. We used weekly minimum and maximum surface temperature time series acquired by MODIS satellites at a spatial resolution of 1000 m and downscaled at 500 m using topographical variables. Two types of analyses were performed:

Context and purpose of the study. Cultivation techniques are widely recognized for their significant impact on the aroma profile of grapes and wines.

Variations in average growing season and ripening season temperatures within the Walla Walla Valley American Viticultural Area are related to elevation and regional and local topography.