Terroir 2020 banner
IVES 9 IVES Conference Series 9 International Terroir Conferences 9 Terroir 2020 9 History and innovation of terroir 9 Using image analysis for assessing downy mildew severity in grapevine

Using image analysis for assessing downy mildew severity in grapevine

Abstract

Aim: Downy mildew is a crucial disease in viticulture. In-field evaluation of downy mildew has been classically based on visual inspection of leaves and fruit. Nevertheless, non-invasive sensing technologies could be used for disease detection in grapevine. The aim of this study was to assess downy mildew severity in grapevine leaves using machine vision.

Methods and Results: Leaf disks of the cv Pinot Noir (Vitis vinifera L.) were placed in Petri dishes with the abaxial side up. Plasmopara viticola sporangia were collected from infected leaves in the vineyard and used for the experimental inoculation of the leaf disks in laboratory. Images of Petri dishes including different levels of downy mildew infection were taken using a digital RGB camera. Machine vision techniques were used to estimate downy mildew severity (percentage of pixels representing visual symptoms) on the leaves. The symptoms were evaluated by eight experts, visually estimating the percentage of area showing sporulation. Considering the average evaluation of the experts, the assessment obtained by the new developed algorithm based on computer vision was represented as a R2value of 0.82 and RMSE of 14.34%.

Conclusions:

The results show a strong correlation between the severity computed by machine vision and the visual assessments, opening the possibility of the automated evaluation of downy mildew severity using non-invasive sensors.

Significance and Impact of the Study: The results indicated that machine vision can be applied for assessing and quantify visual symptoms of downy mildew in grapevine

DOI:

Publication date: March 23, 2021

Issue: Terroir 2020

Type: Video

Authors

Inés Hernández1, Salvador Gutiérrez2, Sara Ceballos1, Miriam Alonso1, Umberto Calvo1, Ignacio Barrio1, Fernando Palacios1, Silvia Toffolatti3, Giuliana Maddalena3, Javier Tardaguila1*

1Televitis Research Group. University of La Rioja, 26007 Logroño, Spain
2Department of Computer Science and Engineering, University of Cádiz, 11519 Puerto Real, Spain
3Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Milano, 20133, Milano, Italy

Contact the author

Keywords

Grapevine, downy mildew, non-invasive phenotyping tools, imaging, machine vision

Tags

IVES Conference Series | Terroir 2020

Citation

Related articles…

Grapevine xylem embolism resistance spectrum reveals which varieties have a lower mortality risk in a future dry climate

Wine growing regions have recently faced intense and frequent droughts that have led to substantial economical losses, and the maintenance of grapevine productivity under warmer and drier climate will rely notably on planting drought-resistant cultivars. Given that plant growth and yield depend on water transport efficiency and maintenance of photosynthesis, thus on the preservation of the vascular system integrity during drought, a better understanding of drought-related hydraulic traits that have a significant impact on physiological processes is urgently needed. We have worked towards this end by assessing vulnerability to xylem embolism in 30 grapevine commercial varieties encompassing red and white Vitis vinifera varieties, hybrid varieties characterized by a polygenic resistance for powdery and downy mildew, and commonly used rootstocks. These analyses further allowed a global assessment of wine regions with respect to their varietal diversity and resulting vulnerability to stem embolism. Hybrid cultivars displayed the highest vulnerability to embolism, while rootstocks showed the greatest resistance. Significant variability also arose among Vitis vinifera varieties, with Ψ12 and Ψ50 values ranging from -0.4 to -2.7 MPa and from -1.8 to -3.4 MPa, respectively. Cabernet franc, Chardonnay and Ugni blanc featured among the most vulnerable varieties while Pinot noir, Merlot and Cabernet Sauvignon ranked among the most resistant. In consequence, wine regions bearing a significant proportion of vulnerable varieties, such as Poitou-Charentes, France and Marlborough, New Zealand, turned out to be at greater risk under drought. These results highlight that grapevine varieties may not respond equally to warmer and drier conditions, outlining the importance to consider hydraulic traits associated with plant drought tolerance into breeding programmes and modeling simulations of grapevine yield maintenance under severe drought. They finally represent a step forward to advise the wine industry about which varieties and regions would have the lowest risk of drought-induced mortality under climate change.

Composition and molar mass distribution of different must and wine colloids

A major problem for winemakers is the formation of proteinaceous haze after bottling. Although the exact mechanisms remain unclear, this haze is formed by unfolding and agglomeration of grape proteins, being additionally influenced by numerous further factors.

Caratterizzazione delle produzioni vitivinicole dell’ area del Barolo: un’esperienza pluridisciplinare triennale (5)

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Influenze pedo-ambientali su produzione, qualità e caratteristiche sensoriali dell’Albana di Romagna

L’Albana è il vitigno a bacca bianca tradizionale delle colline della Romagna, dove é presente per più di 2.500 ha. Con le sue uve si produce il vino “Albana di Romagna”, una delle più storiche D.O.C.G. italiane essendo stata costituita nel 1987. La maggiore concentrazione di vigneti di Albana si trova nell’Imolese e nelle colline del Ravennate, ma ben conosciuta per la qualità del prodotto é anche la produzione di Bertinoro, nel Forlivese.

Non Saccharomyces wine yeasts: emerging trends and challenges in winemaking

In the past, the contribution of non-Saccharomyces yeasts in winemaking has always been considered negative for their limited enological attitude if compared with Saccharomyces cerevisiae. In recent decades there has been a reevaluation of the role of non-Saccharomyces wine yeasts especially when used in combination and in support with S. cerevisiae (mixed fermentation). In this regard, selected non-Saccharomyces yeasts could be profitable used to give distinctive features, to enhance flavor and aroma complexity and to reduce the ethanol content of wines. Further emerging trends in the use of these yeasts are related to their role as bioprotectants and producers of health promoters compounds.