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.

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. 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.

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.

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