Is the Emergence of Dothistroma Needle Blight of Pine in France Caused by the Cryptic Species Dothistroma pini?

International audienceDothistroma needle blight (DNB) emerged in France in the past 15 years. This disease is induced by two closely related species Dothistroma septosporum and D. pini. While both species are nowadays present in France, only D. septosporum was reported in the past. We investigated whether a recent arrival of D. pini in France could be a cause of the DNB emergence. We analysed herbarium specimens of pine needle with DNB symptoms using PCR techniques to study the past frequency of D. pini in France. We also determined the present distribution within the country of D. septosporum and D. pini and compared it to the spatial pattern of DNB report in the DSF data base (french forest health monitoring agency). Although D. pini was detected on herbarium specimens from 1907 and 1965, it was not frequent in France in the past. It is nowadays frequent although not present throughout the country, being absent from the north and the east. There is no relationship between the D. pini distribution in France and the spatial pattern of DNB report in the DSF database. Thus, the emergence of DNB in France cannot be explained by a recent arrival of D. pini

Métodos y progreso de la conservación de los recursos genéticos de los olmos en Europa

The progress made in the conservation of European elm genetic resources since the 1st International Elm Conference is reviewed, and the complementarity of in situ and ex situ methods is discussed. The financial support of the European Union to RESGEN project CT96-78 has permitted to co-ordinate and rationalize the ex situ conservation of elms. The project, which involved 17 partner institutes in nine west European countries, aimed at a better evaluation, conservation and utilisation of the existing collections of native elm clones. Main achievements are: establishing a common database of about 2,000 clones; characterizing over 500 clones through RAPDs and chloroplast DNA PCR-RFLPs molecular markers; completing and rationalizing the existing collections; establishing a long-term core collection of 850 clones; cryo-preserving a subset of 444 clones; and identifying clones of interest for breeding and prudent use in the reconstruction of countryside hedges. The «Noble Hardwoods» network of the pan-European programme EUFORGEN groups members representative of 31 countries, and promotes the dynamic conservation of the genetic resources of several genera of broadleaf forest trees, including Ulmus spp. Strategies for the conservation of the adaptive potential of elm resources were defined and will be disseminated among foresters and conservationists through «Guidelines» leaflets. Some countries have already started implementing conservation measures for U. laevis, associating in situ preservation and the establishment of seed orchards. Others are undertaking inventories, or acquiring genetic knowledge on target populations.Se discute el progreso realizado en la conservación de los olmos europeos desde la primera conferencia Internacional del Olmo y los métodos complementarios de conservación in situ y ex situ. El apoyo financiero de la Unión Europea al proyecto RESGEN CT96-78 ha permitido coordinar y racionalizar la conservación ex situ de los olmos. El proyecto, en el cual están involucrados 17 instituciones participantes en nueve países de Europa Occidental, tiene por objetivo una mejor evaluación, conservación y utilización de las colecciones actualmente existentes de clones nativos de olmo. Los principales logros son: el establecimiento de una base de datos común de aproximadamente 2.000 clones; la caracterización de más de 500 clones usando RAPD y marcadores moleculares PCR-RFLP de ADN cloroplástico; la finalización y racionalización de las colecciones existentes; el establecimiento a largo plazo de una colección central con 850 clones; la criopreservación de un conjunto de 444 clones; y la identificación de clones de interés para la mejora y para su uso en la restauración de setos en campo. La red «Noble Hardwoods» del programa pan-europeo EUFORGEN agrupa a miembros representantes de 31 países, y promueve la conservación dinámica de los recursos genéticos de varios géneros de árboles planifolios, incluido Ulmus spp.. Las estrategias para la conservación del potencial adaptativo de los recursos de los olmos se definieron y se dieron a conocer entre forestales y conservacionistas a través de folletos guía. Algunos países han comenzado ya a implementar medidas de conservación para U. laevis mediante el uso de la preservación in situ y el establecimiento de huertos semilleros. Otros están elaborando inventarios, o adquiriendo información genética de poblaciones de interés

Rôle d'Hylobius abietis (L) (Col, Curculionidae) dans le transport de Leptographium procerum (Kendr) Wingf et son inoculation au pin sylvestre

International audienc

Rôle d'Hylobius abietis (L) (Col, Curculionidae) dans le transport de Leptographium procerum (Kendr) Wingf et son inoculation au pin sylvestre

On a étudié la fréquence des associations entre Hylobius abietis et divers champignons, dans 4 parcelles de la forêt d'Orléans en 1989 et 1990, d'une part, et dans plusieurs localités des Vosges et du Massif central en 1990, d'autre part. Seul Leptographium procerum se montrait véritablement lié à l'hylobe. La fréquence de contamination de l'insecte par ce champignon variait fortement d'un site à l'autre. Elle était également fonction, semble-t-il, de la date des prélèvements. Les émergents immatures, mâles et femelles, pouvaient également être contaminés par L procerum, mais cette contamination ne semblait pas avoir d'effet sur leur poids. L procerum a, par ailleurs, été isolé de plants de pin sylvestre (Pinus sylvestris L) morts à la suite de morsures de maturation de l'insecte. Des inoculations de L procerum au niveau de larges blessures, pratiquées artificiellement sur des plants de pin sylvestre et imitant les dégâts d'hylobe, ont provoqué la mort de tous les plants. Leur système racinaire et, à un moindre degré, leur partie aérienne étaient envahis par le champignon. Les plants témoins, blessés de la même façon mais non inoculés, ont tous survécu. Ces résultats suggèrent que L procerum pourrait être en partie responsable de la mortalité des plants observée dans les reboisements attaqués par l'hylobe.Possible role of Hylobius abietis (L) in the transport of Leptographium procerum (Kendr) Wingf and in the infection of Scots pine. The aim of this study was to determine the fungus species liable to be conveyed by the pine weevil Hylobius abietis, considered to be the main pest of coniferous reafforestations. The study concentrated mainly on the frequency variations of each isolated fungus in 4 Scots pine stands in the Orléans forest (centre of France) in 1989 and 1990, and in 2 mountainous sites (Vosges and Massif Central) in 1990. Leptographium procerum alone - because of its relatively frequent association with the adult insects during the 2 years and in all trapping sites - appeared to have a link with the pine weevil (table I). The contamination frequency due to this fungus revealed important variations from one site to another (figs 1, 2), but the contamination also seemed to depend on the collection period during the year (fig 3). The immature emergents, both male and female, could also be contaminated (table II). This contamination was probably linked to the development of L procerum in its saprophytic phase. The contamination by L procerum did not seem to have any effect on the weight of the emergents. The fungus had also been isolated from dead Scots pine (Pinus sylvestris L) seedlings, after feeding damage by the pine weevil. Inoculations at the collar with patches of agar cultures on 12 seedlings with artificial substantial wounding revealed high mortality whereas the wounds alone did not lead to mortality. In that case, L procerum developed mainly in the root part of the seedlings and rarely in the aerial part (fig 4). These experiments suggest that L procerum could increase the mortality rate of seedlings after partial feeding damage by the pine weevil