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National audience; L’esca est aujourd’hui la maladie du bois de la vigne la plus préoccupante en France. Selon les données obtenues par l'Observatoire National, sa progression a été constante de 2003 à 2008. Plusieurs hypothèses peuvent, individuellement ou conjointement, expliquer cette augmentation. Parmi elles, citons (i) l’interdiction de l’arsénite de soude en 2001, (ii) une décennie marquée par de fortes vagues de chaleur (2003, 2006) ou des sécheresses prolongées (2005, 2009, 2010), (iii) la qualité du matériel végétal et (iv) enfin les changements dans certaines pratiques viticoles. Au cours de la dernière décennie, un suivi basé sur l’apparition et le développement des symptômes foliaires a également été réalisé, principalement dans le Bordelais. Les résultats ont montré que les symptômes d’esca incluent des symptômes attribués par ailleurs au ‘black dead arm’. En Europe et sur le pourtour méditerranéen, les symptômes d’esca ont été très fréquemment associés à un désordre vasculaire très singulier: une lésion du bois externe, de couleur orangée, superficielle, longitudinale, plus ou moins large, située juste sous l’écorce et dans la continuité des symptômes foliaires. Ces observations soulèvent de nouvelles questions quant à l'étiologie de l'esca.

International audience

International audience; Eutypa dieback is a vascular disease that may severely affect vineyards throughout the world. In the present work, microarrays were made in order (i) to improve our knowledge of grapevine (Vitis vinifera cv. Cabernet-Sauvignon) responses to Eutypa lata, the causal agent of Eutypa dieback; and (ii) to identify genes that may prevent symptom development. Qiagen/Operon grapevine microarrays comprising 14,500 probes were used to compare, under three experimental conditions (in vitro, in the greenhouse, and in the vineyard), foliar material of infected symptomatic plants (S(+)R(+)), infected asymptomatic plants (S(-)R(+)), and healthy plants (S(-)R(-)). These plants were characterized by symptom notation after natural (vineyard) or experimental (in vitro and greenhouse) infection, re-isolation of the fungus located in the lignified parts, and the formal identification of E. lata mycelium by PCR. Semi-quantitative real-time PCR experiments were run to confirm the expression of some genes of interest in response to E. lata. Their expression profiles were also studied in response to other grapevine pathogens (Erysiphe necator, Plasmopara viticola, and Botrytis cinerea). (i) Five functional categories of genes, that is those involved in metabolism, defence reactions, interaction with the environment, transport, and transcription, were up-regulated in S(+)R(+) plants compared with S(-)R(-) plants. These genes, which cannot prevent infection and symptom development, are not specific since they were also up-regulated after infection by powdery mildew, downy mildew, and black rot. (ii) Most of the genes that may prevent symptom development are associated with the light phase of photosynthesis. This finding is discussed in the context of previous data on the mode of action of eutypin and the polypeptide fraction secreted by Eutypa.

Summary: Located at the junction of the marine field and the continental field, the bay of Bourgneuf is the third larger shellfish basin of France. The durability of the activities at the bay is linked to the maintenance from a good quality of coastal water. The coastal water are heavily impacted by multiple uses which involve conflicts and wastings. In such a context, this study leads to an Integrated Coastal Zone Management (ICZM) in seeking to develop tools for the ecological and economic management durable of the ground-sea interface. The originality of this work lies in the coupling of three models each corresponding to one of the three coastal compartments (watershed, marsh, bay). This allows to evaluate 1) flows of water and materials (MIS, nutrients, bacteriology, pesticide) coming from the watershed, 2) their transfer through the marsh which was

International audience; Eutypa dieback symptoms on grapevine have been reported in Rioja Alavesa since the nineteen eighties. However, attempts to find the perithecia of Eutypa lata in vineyards were not successful. Old vineyards in the Rioja Alavesa region were inspected for the presence of such perithecia. They were eventually detected in a 80-year-old Tempranillo vineyard in Laguardia. The morphology and size of the perithecia and the ascospores, as well as the colony features of the isolates on PDA were in agreement with those previously described for E. lata. The identification was confirmed by PCR using specific primers, as well as by sequence analysis of the rDNA ITS1/5.8S/ITS2 region. This is the first report of perithecia of E. later in Rioja Alavesa and will improve understanding of the disease cycle of Eutypa dieback of grapevine in this region.

International audience

International audience; The incidence and quantification of decline-associated inner necrosis in grapevine rootstock mother plants have rarely been studied. In an experimental vineyard planted in 1991 at Saintes (Charentes), susceptibility to esca was evaluated in eleven common rootstock varieties. Fifty vines per rootstock variety were used as mother plants producing long canes which were severely pruned every year. No foliar symptoms, typical of grapevine wood diseases, were seen in field inspections conducted in the summer of 1996, 2002, 2003 and 2006. In 2007, nine trunks per variety were randomly selected and were cross-sectioned at the point of greatest diameter. All sections revealed typical esca necrosis, central and/or sector-shaped, indicating that such necrosis is very common. Every section was photographed and the percentage of necrotic area was calculated by either visual assessment or image-analysis. No significant difference was detected between these two calculating methods. Based on the mean percent necrotic area, rootstock varieties were ranked in order of susceptibility from the least susceptible, '1103 Paulsen' (33%), to the most susceptible, '101-14 MGT' (71%). The percent of necrotic area was correlated significantly with i) the incidence of mortality and ii) the percentage of vine sections showing white rot, a type of necrosis indicating an advanced stage of wood deterioration. This study confirmed that necrosis in grapevine wood is not always associated with foliar symptoms, but that it is related positively with grapevine mortality. Furthermore, wood necrosis in mother-plants poses a risk of disseminating associated fungi through propagation material.

The instrument and products monitoring is an essential tool to efficiently exploit the ESA operational products. The main goal of the monitoring activities is to provide to the science community a reliable and coherent dataset, avoiding that erroneous input data is used for the scientific analysis. The Quality Control (QC) process is based on a day-to-day operational monitoring that allows the timely detection of instrument and product anomalies. In addition, the QC tasks include the long term analysis of instrument and product key quality indicators allowing to assess the instrument performances, to prevent degradation and to drive corrective actions. The value of the QC service for the science user was demonstrated during the operations of ERS and ENVISAT satellites. The QC service will play a crucial role in future ESA missions, not only for the satellite operations, but also for supporting the definition of the products template, of the monitoring baseline and of the Calibration and Validation plan and as a vital source of information to the users.

Vineyard experiments were conducted over five years in the Bordeaux area to evaluate the effectiveness of trunk injections in controlling Eutypa dieback (4 trials) and esca (1 trial). Single treatments were applied in winter 2001 or 2002 using the tree injector StemJect®. Three compounds were tested: two triazole-derived fungicides, propiconazole and difenoconazole, and one elicitor, 2-hydroxybenzoïc acid. Symptomatic vines of two susceptible cultivars, Cabernet Sauvignon and Cabernet Franc, had first been identified in summer in the year before the treatments were started. A disease scale was used to rate the severity of the foliar symptoms. After treatment, disease development was recorded on the same vines in the following years, from 2002 to 2005. Analyses were based on the evolution of foliar symptoms and on the development of wood symptoms (% area of dead wood). This novel procedure made it possible to determine the sanitary status of each vine in terms of three classes of disease severity: remission of symptoms, stability or worsening. No treatment had a significantly durable effect on disease expression irrespective of the site, the compound or the disease studied. Some phytotoxic effects with the triazole fungicides were noticed. Prospects for trunk injections as a means to solve these insidious problems in viticulture are discussed.

Recycling vine wood pruned in winter in the vineyard, after grinding and composting, might pose a risk of recontamination with fungi associated with grapevine decline. The survival of four ascomycete fungi (Botryosphaeria obtusa, Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and Eutypa lata) in composted material was investigated in a 3-year study conducted in the Bordeaux area. Naturally and artificially infested material was examined before and after composting using classical isolation procedures. Results clearly showed that a composting process can eradicate the four target fungi efficiently.

Grapevine, cultivated mostly in the Bekaa Plain, is one of the most important fruit crops in Lebanon. During July 2004, a survey was made in 11 vineyards of local table or wine grapes to evaluate the sanitary status of the grapevine industry as far as wood declines are concerned. The most common grapevine decline was esca. The two forms of the disease (mild and severe) were observed. The mild form was characterized by leaf symptoms consisting of interveinal necrotic spots with yellow or red chlorotic blotches on white and red cultivars. The severe form was characterized by dieback of one or more shoots, leaf drop, shrivelling, and drying of fruit clusters. In west Bekaa, on cv. Cabernet Sauvignon, some vines showed symptoms identical to those of Eutypa dieback such as stunted chlorotic shoots with small, distorted leaves; moreover, symptoms corresponding to black dead arm (BDA) such as wine red spots on the margins of leaves and dry spots were seen as reported earlier (1). Diseased vines of various cultivars were collected: 10 Cabernet Sauvignon (7 esca, 3 BDA, and 1 Eutypa dieback), 4 Beitamouni, 3 Carignan, 2 Teifihi, 1 Zeitouni, 1 Mourverdre, 1 Caladoc, and 1 Merlot. In wood, cross sections through the trunk were made that showed mainly central necrosis, white heart rot, brown red wood, and black spotting. Wedge-shaped lesions were the least common. Particularly for BDA, peeling off the bark revealed a brown streaking of the external wood. Isolations were made on malt agar (MA) with wood chips cut from the different necroses described above. Fungal identifications were based on morphological characteristics in comparison with French isolates after subculturing at 20 to 22°C: Fomitiporia sp. (F85-1), Phaeomoniella chlamydospora (F85-2), Eutypa lata (BX1-10, 8D, and 8F), and Botryosphaeria obtusa (F99-1). The fungus most frequently isolated from central necrosis with white heart rot was the basidiomycete Fomitiporia sp. (35% of vines). Cultures of Fomitiporia sp. on MA reached 4 to 5 cm in diameter after 2 weeks and were yellowish to brownish without conidia. P. chlamydospora (associated with esca, black goo, or Petri disease) was isolated from only 9% of vines investigated. Cultures of P. chlamydospora on MA were slow growing and reached 7 to 8 mm in diameter in the dark after 8 days. Colonies were white but became light green and later became dark green. Sporulation was abundant. E. lata (causing Eutypa dieback) was isolated from the vine of cv. Cabernet Sauvignon showing typical symptoms and from two vines showing symptoms of esca only. Two strains produced characteristic pycniospores, and all strains were identified using polymerase chain reaction (Primer Scar 10A-10B) (2). Among the saprophytic fungi isolated from the different kinds of necroses, either central, wedge-shaped, or under the bark, B. obtusa associated with BDA was found most commonly (65% of vines). Cultures of B. obtusa were gray brown with dense aerial mycelium. Pycnidia started to form after 4 to 5 days and conidia (20 to 26 × 9 to 16 μm) were dark brown when mature. These results are consistent with previous descriptions. To our knowledge, this is the first report of black dead arm in Lebanon. References: (1) P. Larignon et al. Phytopathol. Mediterr. 40:S336, 2001. (2) P. Lecomte et al. Appl. Environ. Microbiol. 66:4475, 2000.

Eutypa latais the causal fungal agent ofEutypadieback, a serious grapevine necrotic disease. The erratic and delayed (1 to 2 months) appearance of characteristic conidia on culture media and the presence of numerous microorganisms in decaying wood make it difficult either to identify or to detectE. latain grapevine wood samples. We designed six pairs of PCR primers for diagnosis ofE. lata. Three primer pairs were derived from ribosomal DNA internal transcribed spacer sequences, and three pairs were derived from randomly amplified polymorphic DNA fragments. The six primer pairs could be used to amplify DNAs extracted from all of theE. lataisolates tested. They did not amplify DNAs from fungi and bacteria representing more than 50 different species of microorganisms associated with grapevine. We developed a simple protocol, leading to a rapid release of DNA, that enabled us to identifyE. latafrom pure or mixed cultures as well as from grapevine wood samples. Identification ofE. latain wood was achieved within a few hours, instead of the several weeks required for classical cultures on agar medium. We believe that the procedure described here can be adapted to detect other microorganisms involved in woody plant diseases.

The thermal sensitivity of Erwinia amylovora was determined at 45° C and 50°C. In vitro assays with eight differetit strains showed that thermal death times did not exceed 70min at 45° C and 50min at 50° C (95% confidence interval). Heat treatments of naturally infected apple and pear shoots were performed using a moist and a dry heat procedure. When shoots were wrapped in wet cotton cloths (wet heat) and maintained in an incubator, no bacterial growth could be detected after an incubation of 5 h at 45° C. When shoots were sealed in polyethylene bags and immersed in water (dry heat), no Erwinia amytovora could be isolated after an immersion of 3 h at 45° C. Incubation at 50°C for 1 –2h in either condition did not eradicate the pathogen entirely. The failure rate of grafts using budwoods treated at the effective time-temperature combinations did not exceed 25%. The present investigations showed that the use of thermotherapy techniques for controlling Erwinia amylovora in propagation material of apple and pear might be possible.

no. spécial : Fire Blight

Assessment of the susceptibility to [i]Erwinia amylovora[/i] of 90 varieties or selections of Pear

The fireblight susceptibility of 75 named cv. of apple and of two Malus species has been evaluated through artificial inoculation, during 3 or 4 consecutive years for shoots inoculation and 2 consecutive years for flowers inoculation. The result of shoot inoculations are assessed in 5 classes of a varietals index susceptibilty (V.I.S.).

National audience