New multipest damage indicator to assess protection strategies in grapevine cropping systems

Abstract

Background and Aims Social, environmental and regulatory evolution encourages grapegrowers to reduce chemical use. Organic production is one possible answer, but controlling pests and diseases by products allowed in organic production is less easy than with chemicals. We integrated disease severity levels (Botrytis bunch rot, powdery and downy mildews) and pest incidence (grape berry moths) to develop an indicator of pests and disease damage in grape bunches, named assessment indicator of damage in grape bunches (AIDB), which can be used to assess pest incidence in networks of grower vineyards.Methods and Results In 2011 and 2012, we tested AIDB by monitoring damage at key phenological stages in 20 vineyards in the Bordeaux and Languedoc regions in the south of France, under three modes of production: conventional production, organic production and in conversion to organic production. The indicator proved accurate in describing the total damage on grape bunches under all conditions tested.Conclusions Irrespective of the mode of production, the AIDB value was negatively correlated with yield parameters and the technical expertise of the grower. This indicator proved to be an innovative tool to estimate the multipest damage on grapevines over a range of conditions.Significance of the Study The AIDB enables grapegrowers and advisors to assess the integrated impact of their treatment strategies on grape production, which is necessary when reducing pesticide use

Diversity of conversion strategies for organic vineyards

“…A significant drop in per-hectare yields in organic farming compared to conventional agriculture has been observed (de Ponti et al 2012;Seufert et al 2012), but related economic losses have not been demonstrated. For grapevines, the risk of yield losses seems to be important during organic conversion because grape yields are highly sensitive to pests and diseases (Fermaud et al 2016). Organic farming labor requirements and total costs per hectare can be two or three times greater than those in conventional agriculture (Aubert and Enjolras 2017) depending on cropping choices (e.g., mechanization) and pre-conversion synthetic chemical dependency.…”

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

“…These high figures are due to vineyards being extremely sensitive to attacks from pests and diseases such as powdery and downy mildew [7,8]. If not controlled, powdery and downy mildew expose winegrowers to a risk of low to null harvest [9]. In light of this environmental context and rising consumer demand, organic vineyard areas have increased since 2000.…”

“…Water or nitrogen stresses are essential limiting factors of yield that constrain the number of inflorescences and the number of berries at the sensitive period [13]. Delayed bud pruning can result in poor vine canopy management, which can then lead to a degraded microclimate around clusters and higher disease severity [9]. For pest and disease control, alternative products based on copper, sulfur or biocontrol exist.…”

Converting to organic viticulture increases cropping system structure and management complexity

“…During conversion, farmers must stop using synthetic chemicals and mineral fertilization to comply with organic farming certification requirements. Substituting inputs allowed in organic farming (e.g., copper instead of systemic fungicides) for synthetics may be considered a minor change but in practice requires significant changes in crop management to avoid declines in yield and/or grape quality (Fermaud et al 2016). In vineyards, major outbreaks of certain diseases can stem from just one poor application of fungicide and result in a near total yield loss (Caffi et al 2010).…”

“…The technical and biophysical subsystems are influenced by the decisional subsystem, which comprises decision rules for crop land allocation, crop combinations (in space and time), and crop management (Le Gal et al 2010). These decision rules are activated by management indicators (Fermaud et al 2016).…”