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National audience; Decreasing pesticide use in orchards is a major challenge to increase their sustainability. The study of pest management strategies and their determining factors is important to evaluate if these strategies can provide reductions in pesticide use. Decision-making in orchards is influenced by the high risk of fruit damage and yield loss due to the permanent presence of pests in a perennial system, as well as market standards for 'zero damage' fresh fruits. In this context, we focused on the middle Rhone Valley in southeastern France, where many producers have switched from peach to apricot production in the last two decades due to an economic and sanitary crisis. We addressed the following questions: is new orchard planting an opportunity to rethink pest management strategies? How do technical constraints and socioeconomic aspects (e.g., commercial outlets, information networks, technical support) influence decision-making? A survey was conducted with 35 apricot and peach producers. The interviews focused on pest management strategies and the adoption of alternative methods, recent farm pathways, marketing channels and information and technical networks. Drivers, bottlenecks and opportunities to adopt alternative methods and to design more ecological pest management strategies were identified. Orchard planting was not so much a prerequisite for orchard redesign as was the progressive integration of various alternative methods in existing or replanted orchards. Our results also emphasized the interdependencies between farmers' pest management strategies and pesticide regulations, food chain constraints and information systems: farmers advised by input sellers used more pesticides than those with no or independent advisors; farmers selling through short distribution channels used fewer pesticides than those selling through farmers' organizations, brokers or wholesalers. Promising levers have thus been identified to reduce pesticide use, but their application and diffusion often fail due to inadequate regulatory compliance and/or technical support systems. Therefore, orchard transition towards ecologization and pesticide reduction should be facilitated through a deeper redesign at the scale of the agri-food system.

The French apricot production is located in the South-Eastern part of the country and focused both in the Rhone valley and close to the Mediterranean Sea. The north of the Rhone valley is characterized by a continental climate while the southern region (Rhone valley and Mediterranean area) is under warm typical Mediterranean climate. Obviously apricot fruit production depends on a specific panel of cultivars in each area of cultivation due to economic and adaptation constraints. In order to enlarge the panel of cultivars to be developed by the growers in each region an integrated breeding program is developed at a national level in France with the participation of INRA, CENTREX and CEP INNOVATION. The main goals of the breeding program are: the elaboration of cultivars suitable for a durable production (including resistance to pests and disease), production regularity (including self-fertility and quality of the flowers), and fruit quality (including taste, attractiveness, and suitability for the transport). The evaluation phase is organized in the 3 main areas of production (Perpignan, Nimes, Valence) and follows 3 complementary evaluation stages (i) observation of the hybrid on its own roots; (ii) evaluation of the best hybrids after grafting in the 3 main areas; (iii) assessment of the agronomic and commercial interest of the 'elite' accessions in small orchards. The main results issued from this program are presented: 8 registered cultivars, 4 new selections under registration, and the first PPV resistant cultivar 'Aramis' ® 'Shamade'.

INRA, CENTREX and CEP INNOVATION are developing new apricot cultivars for French growers with particular attention paid to consumer's expectations. The main objectives of the related breeding programme are: production regularity, fruit quality and attractiveness. Their evaluation is based on a multilocal and pluri-annual set of trials located in the three major French areas of cultivation and organised as a 3-stage-evaluation: (i) observation of the seedlings on their own roots (ii) evaluation of the best grafted selections in the 3 main areas, (iii) assessment of the agronomic and commercial interest of the 'elite' accessions in small commercial orchards. At the end of the selection process two recent main types of cultivars have been introduced: - Ten new cultivars able to enlarge the harvesting season by 'conventional' type of fruit ('Soledane', 'Solimar'@, 'Candide', 'Bergerval'@, 'Bergarouge'®, 'Royal Roussillon', 'Vertige', 'Fantasme'@, 'Helena du Roussillon'®, 'Frisson'); - Three new fruit-type apricots characterized by a stark red blush covering 80% of the fruit shape, developed under the same trademark, 'Rubisco'@ (Ravival, Ravilong and Ravicile).

International audience; In gene-for-gene interactions, avirulence genes interact, directly or not, with host resistance genes, triggering several defense mechanisms and resulting in no disease development. This kind of interaction was shown to occur in many host-pathogen relationships, including the one between Malus * domestica and Venturia inaequalis, the causal agent of apple scab. In the specific interaction between the host cultivar 'Golden Delicious' and V. inaequalis race 7, both the resistance gene Vg and the avirulence gene AvrVg have been identified and their map position determined in the host and in the pathogen genome respectively. Focusing on the fungal avirulence gene AvrVg, we constructed a genomic library of an AvrVg avirulent isolate and performed a chromosome walking, isolating and sequencing a 330 kb genomic region carrying this gene. Four different in silico gene predictions were performed on the genomic sequence resulting in a total of 169 genes grouped in 60 coding regions, some predicted by all four predictions to encode for the same identical protein and other regions where differences between the different predictions were found in the splicing sites. A second analysis was performed by software, allowing the identification of 40 regions coding for genes predicted to be secreted extracellularly, either by signal peptide or by non-classical secretion, these being the most common feature among avirulence genes. The next step toward identification of the real avirulence gene is the investigation of the expression of such candidate avirulence gene identified in silico as well as the examination of their possible alleles in virulent isolates. The results of the in silico gene prediction in the AvrVg region and preliminary results of candidate avirulence gene expression experiments will be presented.

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13. International symposium on fruit tree virus diseases, Bordeaux, FRA (1985/06/17-22); International audience; Apricot chlorotic leaf roll, a mycoplasma disease, is the main cause of Apricot decline in France. From time to time, diseased trees recover after a severe attack. Young trees propagated by grafting from such trees appear resistant to the disease. Sensitive trees may become resistant as well, by inserting into them, tissue from recovered trees or from trees propagated from trees which have recovered. Protected trees display growth and development anomalies more or less severe according to the cultivar, the root-stock, the climate and the source of protection. Taking into account the results of studies in experimental fields and commercial orchards, the application of these techniques are being examined.