Heterobasidion bref. and armillaria (fr.) staude pathosystems in the basque country: identification, ecology and control

114 p.In the temperate forest, root and butt rot fungi are considered the greatest causes of economic losses. Armillaria and Heterobasidion species are often the causative agents of this disease which is characterized by chlorotic leaves, progressive thinning of the crown, slower leader growth, and rapid tree death. In the present study, the distribution of Armillaria and Heterobasidion in the Basque Country, and the environmental factors associated with both fungal complexes, were described. The species and population diversity of both genera in selected plantations and native forests were determined, and host range in the field and host susceptibility to A. mellea under greenhouse conditions were established. The results contribute to a better understanding of the epidemiology of these forest pathogens. In addition, bacteria native to the P. radiata rhizosphere that are able to reduce pathogenic effects of A. mellea and H. annosum s.s in young P. radiata trees were isolated and characterized. The compiled information will facilitate the development of management strategies, especially in areas of the Basque Country where the problem of replanting forests infested by diverse native and exotic pathogens is endemic.Neiker-Tecnalia. Eusko Jaurlaritza. Gobierno Vasco FINBIF Innovation INIA : Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Healthy Fores

Heterobasidion bref. and armillaria (fr.) staude pathosystems in the basque country: identification, ecology and control

114 p.In the temperate forest, root and butt rot fungi are considered the greatest causes of economic losses. Armillaria and Heterobasidion species are often the causative agents of this disease which is characterized by chlorotic leaves, progressive thinning of the crown, slower leader growth, and rapid tree death. In the present study, the distribution of Armillaria and Heterobasidion in the Basque Country, and the environmental factors associated with both fungal complexes, were described. The species and population diversity of both genera in selected plantations and native forests were determined, and host range in the field and host susceptibility to A. mellea under greenhouse conditions were established. The results contribute to a better understanding of the epidemiology of these forest pathogens. In addition, bacteria native to the P. radiata rhizosphere that are able to reduce pathogenic effects of A. mellea and H. annosum s.s in young P. radiata trees were isolated and characterized. The compiled information will facilitate the development of management strategies, especially in areas of the Basque Country where the problem of replanting forests infested by diverse native and exotic pathogens is endemic.Neiker-Tecnalia. Eusko Jaurlaritza. Gobierno Vasco FINBIF Innovation INIA : Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Healthy Fores

Genetic diversity of Lecanosticta acicola in Pinus ecosystems in northern Spain

Lecanosticta acicola is one of the most damaging species affecting Pinus radiata plantations in Spain. Favourable climatic conditions and unknown endogenous factors of the pathogen and host led to a situation of high incidence and severity of the disease in these ecosystems. With the main aim of understanding the factors intrinsic to this pathogenic species, a study of the population structure in new established plantations with respect to older plantations was implemented. The genetic diversity, population structure and the ability of the pathogen to spread was determined in Northern Spain (Basque Country), where two thirds of the total Pinus radiata plantations of Spain are located. From a total of 153 Lecanosticta acicola isolates analysed, two lineages were present; the southern lineage, which was prevalent, and the northern lineage, which was scarce. A total of 22 multilocus genotypes were detected with a balanced composition of both mating types and evidence for sexual reproduction. In addition to the changing environmental conditions enhancing disease expression, the complexity and diversity of the pathogen will make it difficult to control and to maintain the wood productive system fundamentally based on this forest species.FUNDING : This research was funded by Project RTA 2017-00063-C04-03 INIA, the Project Healthy Forest: LIFE14 ENV/ES/000179, the Department of Economic Development, Sustainability and Environment (Basque Government), grant reference: SANFOR2020. Forestry and Agricultural Biotechnology Institute, at the University of Pretoria (FABI).am2024BiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant PathologySDG-15:Life on lan

Root infection of canker pathogens, Fusarium circinatum and Diplodia sapinea, in asymptomatic trees in Pinus radiata and Pinus pinaster plantations

[EN] The existence of a latent stage within host tissue of the pine pathogens Fusarium circinatum and Diplodia sapinea, the causal agents of pitch canker and shoot blight disease respectively, has previously been cited. However, studies on this cryptic phase in each disease lifecycle has only been focused on the host aerial parts but not on the roots. Therefore, our objective was to analyze the presence of both pathogens in roots of non-symptomatic mature trees in plantations where the pathogens are known to be causing canker symptoms. For that, we sampled roots from ten non-symptomatic and ten symptomatic trees in three Pinus radiata and one Pinus pinaster plantations in Basque Country, Spain. Both pathogens were isolated from roots of non-symptomatic trees in a higher frequency than from roots of symptomatic trees, 23.3% and 6.6% respectively for D. sapinea and 16.6% and 3.3% respectively for F. circinatum. Neither pathogens was detected in the P. pinaster plantation. The two pathogens were never isolated from the same tree. A high molecular variability was observed for D. sapinea isolates with six different haplotypes and two mating types for the eleven characterized isolates, but only one haplotype and mating type was found for F. circinatum, with all isolates of both fungi being proved pathogenic. These results evidence the importance root infection may have in the disease lifecycle and, therefore, disease management.We acknowledge Maria Teresa Morales Clemente for her excellent technical assistance. Laura Hernandez-Escribano was supported by a fellowship from INIA (FPI-INIA). Financial support for this research was provided by project RTA2013-00048-C03-01, RTA2017-00063-C04-01 and C04-03 (National Progamme I + D + I, INIA, Spain) and the Project Healthy Forest LIFE14 ENV/ES/000179. This article is-based upon work from COST Action FP1406, Pine pitch canker-strategies for management of Gibberella circinata in greenhouses and forests (PINESTRENGTH), supported by COST (European Cooperation in Science and Technology).Hernandez-Escribano, L.; Iturritxa, E.; Aragonés, A.; Mesanza, N.; Berbegal Martinez, M.; Raposo, R.; Elvira-Recuenco, M. (2018). Root infection of canker pathogens, Fusarium circinatum and Diplodia sapinea, in asymptomatic trees in Pinus radiata and Pinus pinaster plantations. Forests. 9(3):1-15. https://doi.org/10.3390/f9030128S11593Nirenberg, H. I., & O’Donnell, K. (1998). New Fusarium Species and Combinations within the Gibberella fujikuroi Species Complex. Mycologia, 90(3), 434. doi:10.2307/3761403Phillips, A. J. L., Alves, A., Abdollahzadeh, J., Slippers, B., Wingfield, M. J., Groenewald, J. Z., & Crous, P. W. (2013). The Botryosphaeriaceae: genera and species known from culture. Studies in Mycology, 76, 51-167. doi:10.3114/sim0021Wingfield, M. J., Hammerbacher, A., Ganley, R. J., Steenkamp, E. T., Gordon, T. R., Wingfield, B. D., & Coutinho, T. A. (2008). Pitch canker caused byFusarium circinatum– a growing threat to pine plantations and forests worldwide. Australasian Plant Pathology, 37(4), 319. doi:10.1071/ap08036Burgess, T. I., Wingfield, M. J., & Wingfield, B. D. (2004). Global distribution ofDiplodia pineagenotypes revealed using simple sequence repeat (SSR) markers. Australasian Plant Pathology, 33(4), 513. doi:10.1071/ap04067Bihon, W., Wingfield, M. J., Slippers, B., Duong, T. A., & Wingfield, B. D. (2014). MAT gene idiomorphs suggest a heterothallic sexual cycle in a predominantly asexual and important pine pathogen. Fungal Genetics and Biology, 62, 55-61. doi:10.1016/j.fgb.2013.10.013Swart, W. J. (1991). Biology and Control ofSphaeropsis sapineaonPinusSpecies in South Africa. Plant Disease, 75(8), 761. doi:10.1094/pd-75-0761Blodgett, J. T., Kruger, E. L., & Stanosz, G. R. (1997). Sphaeropsis sapinea and Water Stress in a Red Pine Plantation in Central Wisconsin. Phytopathology®, 87(4), 429-434. doi:10.1094/phyto.1997.87.4.429Inman, A. R., Kirkpatrick, S. C., Gordon, T. R., & Shaw, D. V. (2008). Limiting Effects of Low Temperature on Growth and Spore Germination in Gibberella circinata, the Cause of Pitch Canker in Pine Species. Plant Disease, 92(4), 542-545. doi:10.1094/pdis-92-4-0542Landeras, E., García, P., Fernández, Y., Braña, M., Fernández-Alonso, O., Méndez-Lodos, S., … Armengol, J. (2005). Outbreak of Pitch Canker Caused by Fusarium circinatum on Pinus spp. in Northern Spain. Plant Disease, 89(9), 1015-1015. doi:10.1094/pd-89-1015aBragança, H., Diogo, E., Moniz, F., & Amaro, P. (2009). First Report of Pitch Canker on Pines Caused by Fusarium circinatum in Portugal. Plant Disease, 93(10), 1079-1079. doi:10.1094/pdis-93-10-1079aCarlucci, A., Colatruglio, L., & Frisullo, S. (2007). First Report of Pitch Canker Caused by Fusarium circinatum on Pinus halepensis and P. pinea in Apulia (Southern Italy). Plant Disease, 91(12), 1683-1683. doi:10.1094/pdis-91-12-1683cBihon, W., Slippers, B., Burgess, T., Wingfield, M. J., & Wingfield, B. D. (2012). Diverse sources of infection and cryptic recombination revealed in South African Diplodia pinea populations. Fungal Biology, 116(1), 112-120. doi:10.1016/j.funbio.2011.10.006KAY, S. J., AH CHEE, A., SALE, P. O., TAYLOR, J. T., HADAR, E., HADAR, Y., & FARRELL, R. L. (2002). Variation among New Zealand isolates of Sphaeropsis sapinea. Forest Pathology, 32(2), 109-121. doi:10.1046/j.1439-0329.2002.00273.xSmith, H., Wingfield, M. J., de Wet, J., & Coutinho, T. A. (2000). Genotypic Diversity of Sphaeropsis sapinea from South Africa and Northern Sumatra. Plant Disease, 84(2), 139-142. doi:10.1094/pdis.2000.84.2.139Zwolinski, J. B., Swart, W. J., & Wingfield, M. J. (1990). 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(2007). Ips pini (Curculionidae: Scolytinae) Is a Vector of the Fungal Pathogen, Sphaeropsis sapinea (Coelomycetes), to Austrian Pines, Pinus nigra (Pinaceae). Environmental Entomology, 36(1), 114-120. doi:10.1603/0046-225x(2007)36[114:ipcsia]2.0.co;2Stanosz, G. R., Swart, W. J., & Smith, D. R. (1999). RAPD marker and isozyme characterization of Sphaeropsis sapinea from diverse coniferous hosts and locations. Mycological Research, 103(9), 1193-1202. doi:10.1017/s0953756299008382Palmer, M. A. (1985). Shoot Blight and Collar Rot ofPinus resinosaCaused bySphaeropsis sapineain Forest Tree Nurseries. Plant Disease, 69(9), 739. doi:10.1094/pd-69-739Stanosz, G. R., Smith, D. R., & Leisso, R. (2007). Diplodia shoot blight and asymptomatic persistence of Diplodia pinea on or in stems of jack pine nursery seedlings. Forest Pathology, 37(3), 145-154. doi:10.1111/j.1439-0329.2007.00487.xFlowers, J., Nuckles, E., Hartman, J., & Vaillancourt, L. (2001). Latent Infection of Austrian and Scots Pine Tissues by Sphaeropsis sapinea. Plant Disease, 85(10), 1107-1112. doi:10.1094/pdis.2001.85.10.1107Flowers, J., Hartman, J., & Vaillancourt, L. (2003). Detection of Latent Sphaeropsis sapinea Infections in Austrian Pine Tissues Using Nested-Polymerase Chain Reaction. Phytopathology®, 93(12), 1471-1477. doi:10.1094/phyto.2003.93.12.1471Smith, H., Wingfied, M. ., & Coutinho, T. . (2002). The role of latent Sphaeropsis sapinea infections in post-hail associated die-back of Pinus patula. Forest Ecology and Management, 164(1-3), 177-184. doi:10.1016/s0378-1127(01)00610-7Vujanovic, V., St-Arnaud, M., & Neumann, P.-J. (2000). Susceptibility of cones and seeds to fungal infection in a pine (Pinus spp.) collection. Forest Pathology, 30(6), 305-320. doi:10.1046/j.1439-0329.2000.00211.xBihon, W., Slippers, B., Burgess, T., Wingfield, M. J., & Wingfield, B. D. (2010). Sources of Diplodia pinea endophytic infections in Pinus patula and P. radiata seedlings in South Africa. Forest Pathology, 41(5), 370-375. doi:10.1111/j.1439-0329.2010.00691.xFABRE, B., PIOU, D., DESPREZ-LOUSTAU, M.-L., & MARÇAIS, B. (2011). Can the emergence of pine Diplodia shoot blight in France be explained by changes in pathogen pressure linked to climate change? Global Change Biology, 17(10), 3218-3227. doi:10.1111/j.1365-2486.2011.02428.xSwett, C. L., Kirkpatrick, S. C., & Gordon, T. R. (2016). Evidence for a Hemibiotrophic Association of the Pitch Canker Pathogen Fusarium circinatum with Pinus radiata. Plant Disease, 100(1), 79-84. doi:10.1094/pdis-03-15-0270-reMartín-Rodrigues, N., Sanchez-Zabala, J., Salcedo, I., Majada, J., González-Murua, C., & Duñabeitia, M. K. (2015). New insights into radiata pine seedling root infection byFusarium circinatum. Plant Pathology, 64(6), 1336-1348. doi:10.1111/ppa.12376Swett, C. L., & Gordon, T. R. (2016). Exposure to a pine pathogen enhances growth and disease resistance inPinus radiataseedlings. Forest Pathology, 47(1), e12298. doi:10.1111/efp.12298Stanosz, G. R., Blodgett, J. T., Smith, D. R., & Kruger, E. L. (2001). Water stress and Sphaeropsis sapinea as a latent pathogen of red pine seedlings. New Phytologist, 149(3), 531-538. doi:10.1046/j.1469-8137.2001.00052.xBihon, W., Burgess, T., Slippers, B., Wingfield, M. J., & Wingfield, B. D. (2011). Distribution of Diplodia pinea and its genotypic diversity within asymptomatic Pinus patula trees. Australasian Plant Pathology, 40(5), 540-548. doi:10.1007/s13313-011-0060-zAegerter, B. J., & Gordon, T. R. (2006). Rates of pitch canker induced seedling mortality among Pinus radiata families varying in levels of genetic resistance to Gibberella circinata (anamorph Fusarium circinatum). Forest Ecology and Management, 235(1-3), 14-17. doi:10.1016/j.foreco.2006.07.011Nirenberg, H. I. (1981). A simplified method for identifying Fusarium spp. occurring on wheat. Canadian Journal of Botany, 59(9), 1599-1609. doi:10.1139/b81-217Slippers, B., Crous, P. W., Denman, S., Coutinho, T. A., Wingfield, B. D., & Wingfield, M. J. (2004). Combined multiple gene genealogies and phenotypic characters differentiate several species previously identified asBotryosphaeria dothidea. Mycologia, 96(1), 83-101. doi:10.1080/15572536.2005.11833000Alves, A., Linaldeddu, B. T., Deidda, A., Scanu, B., & Phillips, A. J. L. (2014). The complex of Diplodia species associated with Fraxinus and some other woody hosts in Italy and Portugal. Fungal Diversity, 67(1), 143-156. doi:10.1007/s13225-014-0282-9Hyde, K. D., Nilsson, R. H., Alias, S. A., Ariyawansa, H. A., Blair, J. E., Cai, L., … Zhou, N. (2014). One stop shop: backbones trees for important phytopathogenic genera: I (2014). Fungal Diversity, 67(1), 21-125. doi:10.1007/s13225-014-0298-1Dissanayake, A. (2016). Botryosphaeriaceae: Current status of genera and species. Mycosphere, 7(7), 1001-1073. doi:10.5943/mycosphere/si/1b/13Linaldeddu, B. (2016). Botryosphaeriaceae species associated with lentisk dieback in Italy and description of Diplodia insularis sp. nov. Mycosphere, 7(7), 962-977. doi:10.5943/mycosphere/si/1b/8Ariyawansa, H. A., Hyde, K. D., Jayasiri, S. C., Buyck, B., Chethana, K. W. T., Dai, D. Q., … Lücking, R. (2015). Fungal diversity notes 111–252—taxonomic and phylogenetic contributions to fungal taxa. Fungal Diversity, 75(1), 27-274. doi:10.1007/s13225-015-0346-5Úrbez-Torres, J. R., Castro-Medina, F., Mohali, S. R., & Gubler, W. D. (2016). Botryosphaeriaceae Species Associated With Cankers and Dieback Symptoms of Acacia mangium and Pinus caribaea var. hondurensis in Venezuela. Plant Disease, 100(12), 2455-2464. doi:10.1094/pdis-05-16-0612-reSmith, D. R., & Stanosz, G. R. (2006). A Species-Specific PCR Assay for Detection of Diplodia pinea and D. scrobiculata in Dead Red and Jack Pines with Collar Rot Symptoms. Plant Disease, 90(3), 307-313. doi:10.1094/pd-90-0307Schweigkofler, W., O’Donnell, K., & Garbelotto, M. (2004). Detection and Quantification of Airborne Conidia of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, from Two California Sites by Using a Real-Time PCR Approach Combined with a Simple Spore Trapping Method. Applied and Environmental Microbiology, 70(6), 3512-3520. doi:10.1128/aem.70.6.3512-3520.2004Wallace, M. M., & Covert, S. F. (2000). Molecular Mating Type Assay forFusarium circinatum. Applied and Environmental Microbiology, 66(12), 5506-5508. doi:10.1128/aem.66.12.5506-5508.2000Berbegal, M., Pérez-Sierra, A., Armengol, J., & Grünwald, N. J. (2013). Evidence for Multiple Introductions and Clonality in Spanish Populations of Fusarium circinatum. Phytopathology®, 103(8), 851-861. doi:10.1094/phyto-11-12-0281-rIturritxa, E., Ganley, R. J., Wright, J., Heppe, E., Steenkamp, E. T., Gordon, T. R., & Wingfield, M. J. (2011). A genetically homogenous population of Fusarium circinatum causes pitch canker of Pinus radiata in the Basque Country, Spain. Fungal Biology, 115(3), 288-295. doi:10.1016/j.funbio.2010.12.014Elvira-Recuenco, M., Iturritxa, E., Majada, J., Alia, R., & Raposo, R. (2014). Adaptive Potential of Maritime Pine (Pinus pinaster) Populations to the Emerging Pitch Canker Pathogen, Fusarium circinatum. PLoS ONE, 9(12), e114971. doi:10.1371/journal.pone.0114971Garbelotto, M., Smith, T., & Schweigkofler, W. (2008). Variation in Rates of Spore Deposition of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, Over a 12-Month-Period at Two Locations in Northern California. Phytopathology®, 98(1), 137-143. doi:10.1094/phyto-98-1-0137Serra-Varela, M. J., Alía, R., Pórtoles, J., Gonzalo, J., Soliño, M., Grivet, D., & Raposo, R. (2017). Incorporating exposure to pitch canker disease to support management decisions of Pinus pinaster Ait. in the face of climate change. PLOS ONE, 12(2), e0171549. doi:10.1371/journal.pone.0171549Hernandez-Escribano, L., Iturritxa, E., Elvira-Recuenco, M., Berbegal, M., Campos, J. A., Renobales, G., … Raposo, R. (2018). Herbaceous plants in the understory of a pitch canker-affected Pinus radiata plantation are endophytically infected with Fusarium circinatum. Fungal Ecology, 32, 65-71. doi:10.1016/j.funeco.2017.12.001Smith, H., Wingfield, M. J., Coutinho, T. A., & Crous, P. W. (1996). Sphaeropsis sapinea and Botryosphaeria dothidea endophytic in Pinus spp. and Eucalyptus spp. in South Africa. South African Journal of Botany, 62(2), 86-88. doi:10.1016/s0254-6299(15)30596-2Santini, A., Pepori, A., Ghelardini, L., & Capretti, P. (2008). Persistence of some pine pathogens in coarse woody debris and cones in a Pinus pinea forest. Forest Ecology and Management, 256(3), 502-506. doi:10.1016/j.foreco.2008.05.010Oblinger, B. W., Smith, D. R., & Stanosz, G. R. (2011). Red pine harvest debris as a potential source of inoculum of Diplodia shoot blight pathogens. Forest Ecology and Management, 262(4), 663-670. doi:10.1016/j.foreco.2011.04.038Eyles, A., Bonello, P., Ganley, R., & Mohammed, C. (2009). Induced resistance to pests and pathogens in trees. New Phytologist, 185(4), 893-908. doi:10.1111/j.1469-8137.2009.03127.xJunker, C., Draeger, S., & Schulz, B. (2012). A fine line – endophytes or pathogens in Arabidopsis thaliana. Fungal Ecology, 5(6), 657-662. doi:10.1016/j.funeco.2012.05.002Flowers, J. L., Hartman, J. R., & Vaillancourt, L. J. (2006). Histology of Diplodia pinea in diseased and latently infected Pinus nigra shoots. Forest Pathology, 36(6), 447-459. doi:10.1111/j.1439-0329.2006.00473.

Weather Variables Associated with Spore Dispersal of Lecanosticta acicola Causing Pine Needle Blight in Northern Spain

In the last decade, the impact of needle blight fungal pathogens on the health status of forests in northern Spain has marked a turning point in forest production systems based on Pinus radiata species. Dothistroma needle blight caused by Dothistroma septosporum and D. pini, and brown spot needle blight caused by Lecanosticta acicola, coexist in these ecosystems. There is a clear dominance of L. acicola with respect to the other two pathogens and evidence of sexual reproduction in the area. Understanding L. acicola spore dispersal dynamics within climatic determinants is necessary to establish more efficient management strategies to increase the sustainability of forest ecosystems. In this study, spore counts of 15 spore traps placed in Pinus ecosystems were recorded in 2019 and spore abundance dependency on weather data was analysed using generalised additive models. During the collection period, the model that best fit the number of trapped spores included the daily maximum temperature and daily cumulative precipitation, which was associated to higher spore counts. The presence of conidia was detected from January and maximum peaks of spore dispersal were generally observed from September to November.This research was funded by the Spanish Ministry of Science and INIA, grant number: RTA 2017-00063-C04-03, LIFE programme, grant number: LIFE14 ENV/ES/000179 and by the Department of Economic Development, Sustainability and Environment (Basque Government), grant reference: FUNGITRAP2019.S

Comparison of Diplodia Tip Blight Pathogens in Spanish and North American Pine Ecosystems

[EN] Diplodia tip blight is the most ubiquitous and abundant disease in Spanish Pinus radiata plantations. The economic losses in forest stands can be very severe because of its abundance in cones and seeds together with the low genetic diversity of the host. Pinus resinosa is not genetically diverse in North America either, and Diplodia shoot blight is a common disease. Disease control may require management designs to be adapted for each region. The genetic diversity of the pathogen could be an indicator of its virulence and spreading capacity. Our objective was to understand the diversity of Diplodia spp. in Spanish plantations and to compare it with the structure of American populations to collaborate in future management guidelines. Genotypic diversity was investigated using microsatellite markers. Eight loci (SS9-SS16) were polymorphic for the 322 isolates genotyped. The results indicate that Diplodia sapinea is the most frequent Diplodia species present in plantations of the north of Spain and has high genetic diversity. The higher genetic diversity recorded in Spain in comparison to previous studies could be influenced by the intensity of the sampling and the evidence about the remarkable influence of the sample type.This research was funded by INIA, grant number: RTA 2017-00063-C04-03, LIFE programme, grant number: LIFE14 ENV/ES/000179 and by the Basque Government, grant number FUNGITRAP 19-00031. Red pine cone collection in New England and pathogen isolation was funded by USDA Forest Service.Aragonés, A.; Manzanos, T.; Stanosz, G.; Munck, IA.; Raposo, R.; Elvira-Recuenco, M.; Berbegal Martinez, M.... (2021). Comparison of Diplodia Tip Blight Pathogens in Spanish and North American Pine Ecosystems. Microorganisms. 9(12):1-17. https://doi.org/10.3390/microorganisms9122565S11791

Global Geographic Distribution and Host Range of Fusarium circinatum, the Causal Agent of Pine Pitch Canker

Funding: This study was financially supported by COST Action FP1406 (PINESTRENGTH), the Estonian Science Foundation grant PSG136, the Forestry Commission, United Kingdom, the Phytophthora Research Centre Reg. No. CZ.02.1.01/0.0/0.0/15_003/0000453, a project co-financed by the European Regional Development Fund. ANSES is supported by a grant managed by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” programme (ANR-11-LABX-0002-01, Laboratory of ExcellenceARBRE). SW was partly supported by BBSRC Grant reference BB/L012251/1 “Promoting resilience of UK tree species to novel pests & pathogens: ecological & evolutionary solutions (PROTREE)” jointly funded by BBSRC, Defra, ESRC, the Forestry Commission, NERC and the Scottish Government, under the Tree Health and Plant Biosecurity Initiative. Annual surveys in Switzerland were financially supported by the Swiss Federal Office for the Environment FOEN. Acknowledgments: Andrea Kunova and Cristina Pizzatti are acknowledged for the assistance in the sampling. Thanks are due to Dina Ribeiro and Helena Marques from ICNF-Portuguese Forest Authority for providing location coordinates. We thank three anonymous reviwers for valuable corrections and suggestions.Peer reviewedPublisher PD

Distribution and Characterization of Armillaria Complex in Atlantic Forest Ecosystems of Spain

Armillaria root disease is a significant forest health concern in the Atlantic forest ecosystems in Spain. The damage occurs in conifers and hardwoods, causing especially high mortality in young trees in both native forests and plantations. In the present study, the distribution of Armillaria root disease in the forests and plantations of the Basque Country is reported. Armillaria spp. were more frequently isolated from stands with slopes of 20–30% and west orientation, acid soils with high permeability, deciduous hosts, and a rainfall average above 1800 mm. In a large-scale survey, 35% of the stands presented Armillaria structures and showed disease symptoms. Of the isolated Armillaria samples, 60% were identified using molecular methods as A. ostoyae, 24% as A. mellea, 14% as A. gallica, 1% as A. tabescens, and 1% as A. cepistipes. In a small scale sampling, population diversity was defined by somatic compatibility tests and Universally Primed-PCR technique. Finally, the pathogenicity of A. mellea, the species with the broadest host range, was determined on different tree species present in the Atlantic area of Spain in order to determine their resistance levels to Armillaria disease. A significant difference in disease severity was observed among tree species (p < 0.001), with Pinus radiata being the most susceptible tree species and Cryptomeria japonica the most resistant to A. mellea