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Nerine peach. © INRA, MONET René

Pathogen-related harvest losses: analysis and quantification

Vine pests: the strong effects of practices and the environment

Cultivation practices and environmental conditions play a determining role in interactions between vines and their pests.  It is this complex system that is being modelled in the context of the Grapevine Yield Loss project.

Updated on 09/12/2016
Published on 01/12/2016

Vines in a vineyard. © INRA, SLAGMULDER Christian
Vines in a vineyard © INRA, SLAGMULDER Christian

Vine cultivation is characterised by marked variations from one production region to another, or even within the same region.  Furthermore, few data are available on yields, which hampers the modelling of harvest losses.  In this context, a campaign to collect data on vine health which has been ongoing since 2013 in Montpellier and on experimental plots in the Bordeaux region, is trying to achieve this objective. Thus Nathalie Smits from INRA in Montpellier, and Marc Fermaud and Lionel Delbac from INRA in Bordeaux have been able to analyse the impact of pests on grape harvests.

Under the Ecoviti programme, two viticultural systems, without chemical weed-killers or products classified as being a risk, were tested: Innobio (organic farming) and IPM-50 (reduction in the amount of sprayed agents).

 A vine can make up for early losses

Pruning of a woody stem, or vine shoot, during dormancy. © INRA, DORDOR Françoise
Pruning of a woody stem, or vine shoot, during dormancy © INRA, DORDOR Françoise

“We evaluated harvest losses by measuring the percentage surface area of bunches of grapes damaged by different pests and diseases, including powdery mildew”, explains Nathalie Smits. “In 2014, these losses were significantly lower in plants under Innobio and IPM-50 that in untreated controls, and comparable to those obtained with standard plant health treatments; less than 20% of surface area damaged, versus 60% for the controls”.

“Are vines able to make up for losses caused by early damage to their fruit-bearing organs?  We tried to answer this question by inducing damage in experimental plots by pruning or thinning at the start of flowering.  And a compensation process was indeed evidenced, despite the variability of the results depending on the plot and year”.

 Analysing risks specific to each situation

  Mildew infection test on disks of vine leaf to determine the level of resistance of different varieties. © INRA, Dorne, Marie-Annick
Mildew infection test on disks of vine leaf to determine the level of resistance of different varieties © INRA, Dorne, Marie-Annick

The modelling work carried out by the team was designed to find a digital analytical solution to yield losses due to pests and diseases.

First of all, it was necessary to design the system comprising the vine and its principal pests (downy mildew, powder mildew, botrytis, vine moth).  The parameters entered in this system were environmental (temperature, rainfall, etc.) and agricultural (soil and pest management, irrigation, fertilisation, pruning).

An initial version of the analytical model to quantify harvest losses was based on a “healthy vine” system.  A full set of growth and development data on vine was collected.  In its final form, the model will also integrate pest-related parameters and enable a clearer understanding of the risks that characterise each setting for wine production.

Scientific contact(s):

  • Nathalie Smits UMR1230 SYSTEM Joint Research Unit for the Functioning and Management of Tropical and Mediterranean Cropping Systems
  • Marc Fermaud UMR1065 SAVE Joint Research Unit for Vine Health and Agroecology
Associated Division(s):
Environment and Agronomy, Plant Health and Environment
Associated Centre(s):
Montpellier, Nouvelle-Aquitaine-Bordeaux