Reducing pesticide use in French vineyards

France enjoys a worldwide reputation for the quality of its wines, but the sector is a significant user of plant protection products, driven in large part by the threats posed by downy and powdery mildew. The sector has sought to innovate its crop protection practices over recent years and a new booklet highlights the progress made in the country’s DEPHY vineyard demonstration network, including the remarkable trajectories of selected winegrowers.

Called ‘Réduction de l’usage des produits phytosanitaires : trajectoires remarquables du réseau DEPHY FERME’ (‘Reducing the use of plant protection products: remarkable trajectories in the DEPHY Farm network’), the booklet first sets out the context for pesticide use in French vineyards. It notes that France’s 755,000 hectares of vines represents a relatively small share of the country’s total agricultural area but has a relatively high pesticide use, with an average Treatment Frequency Index (TFI) of 14.7 in 2013.

Fungicides account for more than 80% of this TFI, nearly all of them used to combat downy and powdery mildew, which attack leaves and berries and can affect both yields and quality. The average TFI for insecticides is 1.7, representing 12.7% of the overall TFI. Some of these applications are linked to obligatory treatments against leafhoppers which are the vector for flavescence dorée, which affects nearly three-quarters of French vineyards to a greater or lesser extent. Herbicides contributes only 4.5% of the average TFI but are used on more than 80% of the total vineyard area.

As of 2016, the DEPHY vineyard network comprised 49 groups (555 winegrowers) across all of France’s major winegrowing areas, including the best known, such as Champagne, Burgundy, Loire Valley and Bordeaux. Each group is supported by an ‘engineer’ and seeks to identify trajectories for reducing pesticide use within the context of their particular cropping systems. 

The booklet reports on the trajectories of 201 different cropping systems in 31 groups from 2012 through to 2017. In 2011, the average TFI in the DEPHY vineyard network was 13 and, with fluctuations due to pest pressure, had been reduced below 10 in 2017.

The booklet explores some of the levers used to control pests and diseases, and for weed and soil management. To reduce fungicide use, for example, the most common levers are those seeking greater pesticide efficiency (observations and technical bulletins, changes in dose using the Optidose decision support tool and the introduction of drift-recovery sprayers), while the most common mitigation tactics are those which seek to reduce plant vigour or increase aeration through leaf pruning.

For pest control, observations and technical bulletins are again commonly used, as is reduced vigour and greater aeration, though there is a greater uptake of substitution practices, principally sexual confusion and the introduction of beneficials and alternative substances. Substitution practices are the most commonly used methods for weed and soil management, including mechanical weeding, manual or mechanical pruning and the use of plant cover.

The booklet also provides five interesting examples of winegrowers who have reduced their TFIs through the introduction of various alternative methods. These include Philippe Germain’s Burgundy vineyard, which has been awarded Haute Valeur Environnementale (high environmental value) certification while reducing inputs and maintaining yields.

Here, one of the key moves has been the introduction of early mechanical leaf pruning to improve air circulation around the fruiting area, thereby limiting disease pressure from botrytis and powdery mildew and reducing pesticide treatments further down the line.

In Cognac, western France, Bruno Lorion describes the moves he has taken to reduce fungicide and insecticide use, following his earlier work to cut herbicide applications. Key to his significant reduction in TFI has been the use of the Movida and Optidose decision support systems and the purchase of a drift-recovery sprayer.  Coupled with reduced doses, this equipment has seen him cut his fungicide TFI from 14.9 in 2012 to 6.6 in 2017. Some insecticide use remains obligatory because the vines are in an area threatened by flavescence dorée.