Timing of grape downy mildew onset in Bordeaux Vineyards

Chen Mathilde, Brun François, Raynal Marc, Makowski David. 2019. Timing of grape downy mildew onset in Bordeaux Vineyards. Phytopathology, 109 (5) : 787-795.

https://doi.org/10.1094/PHYTO-12-17-0412-R

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Quartile : Q1, Sujet : PLANT SCIENCES

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Psychologie-éthologie-ergonomie

Résumé : Grapevine downy mildew (GDM) is a severe disease of grapevines. Because of the lack of reliable information about the dates of GDM symptom onset, many vine growers begin fungicide treatments early in the season. We evaluate the extent to which such preventive treatments are justified. Observational data for 266 untreated sites for the years between 2010 and 2017 were used to estimate the timing of GDM onset on vines and bunches of grapes in South West France (Bordeaux region) through survival analyses. The onset of GDM was not apparent on vines and bunches before early to mid-May, and the rate of GDM symptom appearance was highly variable across years. Depending on the year, 50% of the plots displayed symptoms between mid-May and late June for vines. For several years, our statistical analysis revealed that the proportion of plots with no symptoms was high in early August on vines (27.5 and 43.7% in 2013 and 2016) and on bunches (between 23 and 79% in 2011, 2013, and 2016). We found a significant effect of the amount of rainfall in spring on the date of symptom appearance. These results indicate that preventive fungicide application is unjustified in many vineyards, and that regional disease surveys should be used to adjust fungicide treatment dates according to local characteristics, in particular according to rainfall conditions in spring.

Mots-clés Agrovoc : fongicide, vigne, symptome, Vitis vinifera, contrôle de maladies, pathologie végétale, vignoble, Enquête pathologique, date de traitement, oidium (manifestation maladies)

Mots-clés géographiques Agrovoc : France

Agences de financement hors UE : Ministère de l'agriculture, Institut Carnot Plant2Pro, Agence Nationale de la Recherche

Projets sur financement : (FRA) SMART-PIC, (FRA) Institut Convergences en Agriculture Numérique

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