Effect of Conversion to Organic Farming on Pest and Disease Control in French Vineyards

Abstract

Since 2006, an increasing number of French vineyards have chosen to convert to organic farming. One major change in vineyard practices includes replacing chemical pesticides with copper and sulfur-based products in line with Council Regulation (EC) No. 834/2007. This change can make overall management and pest and disease control more difficult and potentially lead to yield losses. From 2013 to 2016, a network of 48 vineyard plots, in southern France, under conventional management and in conversion to organic farming were monitored throughout the three-year conversion phase to investigate the grapevine phytosanitary management of four major pests and diseases and variations in control efficiency. The severity of downy and powdery mildew, grape berry moths, and Botrytis bunch rot were assessed and linked to the protection strategy. The findings showed that pests and diseases were controlled in the third year of conversion at similar efficiency levels as in conventional farming. However, the first two years of conversion were a transitional and less successful period during which higher incidences of cryptogamic diseases were observed. This demonstrates a need for winegrowers to receive more in-depth technical advice and support, especially on pest and disease control, during this critical transition period.

Does Conversion to Organic Farming Impact Vineyards Yield? A Diachronic Study in Southeastern France

“…The years 2015 and 2016 presented a similar profile, with a rainfall deficit in summer compared to average and higher ETo. mm; and (iv) number of rainy days, 65.7 d [14]. In 2013, total rainfall was higher than average from April to September.…”

“…The four-year study was undertaken on a plot network of 26 vineyards all planted with the same cultivar (Grenache) of Vitis vinifera in southeastern France. Table 1 presents the characteristics of the plot network [14]. Some of the plots were monitored for two successive years.…”

“…To ensure compliance with organic farming specifications, winegrowers began implementing technical changes as early as C1. To distinguish the effect of the conversion from the effect of the vintage on yield dynamics, we decided to monitor several Cv, C1, C2 and C3 plots for each year of the study [14]. We monitored between 10 and 15 vines per year from 2013 to 2016.…”

“…The vineyard network is located in a typical Mediterranean climate ( Figure 2). The average annual climatic features (data from Meteo France-Station Carpentras-Serres 1981-2010) are as follows: (i) minimal temperature, 8.1 • C; (ii) maximal temperature, 20.6 • C; (iii) rainfall, about 648 mm; and (iv) number of rainy days, 65.7 d [14]. In 2013, total rainfall was higher than average from April to September.…”

“…There is a real risk that winegrowers will make errors during the conversion process. Errors in the phytosanitary strategy can lead to higher annual disease prevalence and a decrease in the number of healthy berries [14].…”