GREENSYS 2009, INTERNATIONAL SYMPOSIUM ON HIGH TECHNOLOGY FOR GREENHOUSE SYSTEMS, 14 TH -19 TH JUNE 2009, QUEBEC, CANADA, MULTICRITERIA EVALUATION OF THE PATHOLOGICAL RESILIENCE OF IN-SOIL PROTECTED CROPPING SYSTEMS M. Tchamitchian, B. Collange and M. Navarrete G. Peyre Écodévelopment Unit, INRA, Domaine St Paul ENITAC, Site de Marmilhat 84914 Avignon CEDEX 9, France BP 35 - 63370 Lempdes Keywords: qualitative evaluation, cropping system, root-knot nematode Abstract Cropping systems in in-soil protected cultivation are often very intensive and are characterized by a very low number of crops in the rotation. They are therefore very fragile with respect to soil-borne pests and diseases, and depend on pesticides. These cropping systems must be redesigned to exploit pesticide free techniques to control these soil-borne pests and diseases. Because these techniques (soil solarisation, chosen intercrop or manure, biofumigation, tolerant cultivars…) are not totally effective, they must be combined to add their effects. Although these techniques are described in the R&D literature, few systems approaches are available to describe their combined effects. Part of this knowledge, though, is held by advisers and growers combining these techniques on farm. Building on the hypothesis that this local knowledge can be combined to the available scientific literature, we design a multicriteria tool to evaluate the properties of candidates cropping systems in in-soil protected cultivation. The properties that are qualified deal with the resilience of the cropping system with respect to the main occurring pests and diseases, and with the environmental impact of the cropping system, taking into account several pests at once. Because the knowledge of the growers and advisers is more qualitative than quantitative, we have chosen a qualitative multicriteria approach. We present here the knowledge and evaluation tree built in the specific case of in-soil protected cultivation cropping systems common in South- east France, cropping systems based on winter salad crops (from 1 to 3 successive crops) associated to a spring cash crop (melon, cucumber, eggplant…). The main pests addressed in this presentation are root-knot nematodes. We advocate then that such a tool can be used with growers and advisers to redesign cropping systems and select the promising ones that will be put into trial in R&D stations. INTRODUCTION Soil-based greenhouse vegetable production is often achieved in intensive cropping systems where several crops follow one another within the year. In these intensive systems, the main reasons for yield losses are soil-borne pests and diseases (Oda, 2007). Until recently, they were controlled by methyl bromide fumigation or by chemical pesticides and fungicides. However methyl bromide has been banned for environmental reasons and the increasingly strict regulations on residues in food product combined with stronger concern for public health result in a drastic decrease of the homologated molecules. Growers are therefore faced with the necessity to find new ways to control soil-borne pests and diseases. Alternative techniques like solarisation, use of nematicide