Utvärdering av Rotfinder för detektion av röta i stående träd

A wood decay detecting instrument, Rotfinder® was evaluated for its accuracy, sensitivity and specificity in detecting decay in standing trees. Five hundred trees were measured in three different stands with Rotfinder at three heights in the stems. The trees were felled and sectioned, and presence or absence of decay was observed for each section. Wood samples were taken from every section and their wood density and moisture content was measured. Rotfinder accuracy of detecting both decayed and healthy trees was 82.7%. The highest sensitivity was obtained at stump height (55.9%). Advanced decay was detected in the 71% of cases while incipient decay was detected in the 23% of cases. Rotfinder has a scale from 0 to 10 which indicates an increasing degree of probability of decay. Rotfinder values higher than 4 indicated more than 90% of probability of finding decay. Rotfinder successful detections (true positives and true negatives) and Rotfinder failures (false positives and false negatives) were compared in terms of moisture content, wood density and N, C, Mg, Ca, K, Na and Mn concentration. True positives had higher moisture content in reaction zone and decay, higher density in reaction zone and higher concentration of calcium and sodium of reaction zone than false negatives. Relationship between Rotfinder values and wood characteristics were studied, and the potassium concentration showed the highest correlation with Rotfinder values

Management of Gremmeniella abietina by means of biological control agents and host resistance

Gremmeniella abietina es un patógeno que produce daños severos en bosques de coníferas. En España produce defoliación, distorsión de ramillos terminales y la muerte de algunos pies. Las medidas de control para prevenir la expansión de la enfermedad incluyen prácticas selvícolas y la aplicación de fungicidas sintéticos, aunque únicamente como medida de emergencia en viveros. La necesidad de gestión de la enfermedad junto con las recomendaciones europeas de usar métodos que no sean químicos, hacen necesario proveer de alternativas para luchar contra la enfermedad. Por ello, el principal objetivo de la presente tesis fue indagar en el uso de métodos alternativos para el control de las infecciones producidas por G. abietina. Para conseguir este objetivo, llevamos a cabo cuatro experimentos en los que se probó el uso de diferentes agentes de control biólogico (hongos endófitos, sus filtrados y aislados infectados con virus) así como el uso de hospedantes resistentes.Departamento de Producción Vegetal y Recursos Forestale

Effect of putative mitoviruses on growth of Gremmeniella abietina isolates in vitro and on its pathogenicity on Pinus halepensis seedlings

Los mitovirus son virus fúngicos que han sido aislados de algunos patógenos forestales que pueden reducir la virulencia del hongo. Se ha llevado a cabo un estudio para evaluar el efecto de la temperatura, el pH y el potencial osmótico en el crecimiento micelial de aislados de G. abietina en laboratorio y para observar el efecto de la presencia de mitovirus en la patogenicidad de G. abietina en plántulas de Pinus halepensis. Los resultados del experimento in vitro mostraron que los aislados infectados con mitovirus presentaron mayor crecimiento micelial que los que no infectados en la temperatura de crecimiento óptimo de 15 ºC. No se observaron efectos en los tratamientos de modificación del pH. Se observaron variaciones en el comportamiento de los aislados infectados por mitovirus en comparación con los no infectados cuando se modificaron los potenciales osmóticos. En el experimento efectuado en el invernadero las necrosis encontradas en plántulas con aislados infectados por mitovirus fueron mayores que las que presentaron las plántulas inoculadas con aislados sin mitovirus.Mitoviruses have been found in several forest pathogens (e.g. Cryphonectria parasitica, Gremmeniella abietina), and because they have been shown to reduce the virulence of host fungi there is a growing interest in studying their use as a biocontrol. This study was carried out to test the effect of temperature (5 ºC, 15 ºC, 25 ºC and 35 ºC), pH (4, 5, 7 and 9) and osmotic potential (-0.6, -1.2, -1.8 and -2.4 MPa) on the mycelial growth of seven G. abietina isolates under controlled laboratory conditions and to observe the effect of the presence of mitoviruses in the pathogenity of G. abietina isolates inoculated to Pinus halepensis seedlings. Four of the isolates hosted mitoviruses and three of them did not. During the in vitro experiment, mycelial growth was recorded every week for a period of 8 weeks. In the greenhouse experiment, once the seedlings started to show symptoms, disease severity was recorded during 5 weeks. At the end of the experiment, plants were carried to laboratory and necrosis length was measured in all of them. Results from in vitro experiment showed that the mitovirus-infected isolates presented larger mycelial growth than the mitovirus-free ones when at the fungi’s optimal growing temperature of 15 ºC. However, no differences in growth behavior were observed between mitovirus infected and non-infected isolates when placed under different pH modifications. When growing at certain osmotic potentials (-0.6 and -1.8 MPa) a reduction in growth of the mitovirus-infected isolates was observed. In the greenhouse experiment, larger necrosis lengths were observed in the plants inoculated with mitovirus infected isolates. The results of this experiment provide further insight into the effects of mitovirus on Gremmeniella abietina isolates.Instituto de Investigación Forestal SostenibleMáster en Investigación en Ingeniería para la Conservación y Uso Sostenible de Sistemas Forestale

Pine species determine fungal microbiome composition in a common garden experiment

The factors shaping the composition of microbial communities in trees remain poorly understood. We evaluated whether the core and satellite fungal communities in five pine species (Pinus radiata, Pinus pinaster, Pinus sylvestris, Pinus nigra, and Pinus uncinata) were shaped by the host species identity. Because the trees had earlier been inoculated with a fungal pathogen (Fusarium circinatum), we also explored the possibilities to detect its presence and potential co-occurrence networks. We found interspecific variation in the fungal community composition and abundance among the different tree species and the existence of a core microbiome that was independent of the host species. The presence of F. circinatum was confirmed in some samples through qPCR but the pathogen did not co-occur with a specific fungal community. The results highlight the importance of host species as a determinant of microbiome assembly in common environments

Accuracy of the Rotfinder instrument in detecting decay on Norway spruce (Picea abies) trees

9 Pág.Rotfinder is a non-destructive decay-sensing apparatus based on resistance measurements in standing trees. The accuracy of Rotfinder in detecting decay was evaluated in 500 standing trees in three Norway spruce (Picea abies) plots. Trees were measured at three heights, 0.30, 0.66 and 1.30m. Sections were later inspected for the presence of decay and reaction zones. Inspected trees were mostly infected by Heterobasidion annosum and showed a large variation in the amount of decay present, ranging from 0.1% to 88.0% of the section. Correctly and incorrectly classified trees were compared in terms of ion and element concentration, density and moisture. Measurements at stump level (0.30m) were more accurate than measurements at breast height (1.30m) where the reaction zone and decay columns showed lower moisture content. The accuracy of Rotfinder increased when trees with small decay columns were regarded as 'non-decayed'. When only trees with more than 15% of the section decayed were regarded as 'decayed', Rotfinder had an accuracy of 0.86 when performing assessments at stump level. False negatives, as opposed to true positives, corresponded to trees with smaller and drier decay columns, drier reaction zones and lower K+ (potassium) concentration in the decay column. False positives corresponded to trees with large sapwood and high sodium content in the sapwood. Rotfinder represents an alternative to the standard method of using increment core observations to assess decay in living trees. © 2011 Elsevier B.V.This research has been partially funded by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) and by “Future Forests” financed by the MISTRA Foundation for Strategic Research. Jonàs Oliva was funded by post-doctoral grant 2008 BP A 00013 from the DURSI-GENCAT.Peer reviewe

Translational research on the endophytic microbiome of forest trees

10 Pág.The concept of translational research refers to the process of harnessing knowledge from basic sciences to impacts beyond the academy. The process involves the transfer of knowledge over three major gaps: first, from knowledge generation to interpretation; second, from interpretation to implementation; and third, from implementation to impacts. In this chapter, we discuss how this process, usually described for medical and health care research, applies to the current research on the microbiomes of forest trees. The discussion is timely because while scientific knowledge about the potential of microbiome engineering to support tree resistance against pests and pathogens is rapidly increasing, practical solutions based on the utilization of the microbiome in forest protection have remained rare. Using the concept of translational research as a framework, we identify some major challenges in the translational process and suggest strategies to overcome them.The work was supported by grants from the Swedish Research Council Formas (nr. 2016-00907) to J. Witzell, from the EU’s Horizon 2020 research and innovation program MSCA (grant agreement no. 845419) to C. Romeralo, and from Ministerio de Ciencia e Innovación, Spain (PID2019-107256RB-I00) to J.A. Martín.Peer reviewe

Aleppo pine provenances vary in susceptibility and secondary chemical response to Gremmeniella abietina infection

9 Pág.Aleppo pine is a thermophilic species that has become a popular tree species in plantings even beyond its natural habitat. In 1999 the pathogenic fungus Gremmeniella abietina was isolated for the first time in Aleppo pine plantations in Spain. The main objective of this study was to analyse the variation in susceptibility to G. abietina (European race, biotype A) infections among trees from five Aleppo pine provenances. Artificial inoculations were performed at two different times in January 2012. The susceptibility of the trees was evaluated by recording disease severity and the length of internal stem necrosis produced by the pathogen. In addition, the concentrations of two flavanone compounds were quantified as putative indicators of resistance. Provenances and G. abietina isolates both significantly affected levels of necrosis although the results were dependent on the time of inoculation. There was a relationship between provenance and resistance, with trees of higher elevation provenances being more susceptible to disease than trees of lower elevation provenances. The amount of naringenin flavanone from trees was significantly different between provenances, suggesting that it is a possible indicator value for resistance. Conversely, no differences were found in the concentration of eriodictyol in trees between provenances. The results show that the provenance-dependent variation in the susceptibility of Aleppo pine to G. abietina should be considered in selection of seed sources for restoration.This study was financed by the Spanish Ministry project, ‘Biological control of Gremmeniella abietina in Spain (AGL2008-03622)’. A.R. Benitez offered valuable help with the inoculations. The authors wish to thank the Short-Term Scientific Mission of the COST action FA1103 for their economic support.Peer reviewe

Forest diversity and productivity: Implications for forest health in future climates

Pág.11Tree species diversity is an important determinant of the capacity of forests to support biodiversity and provide multiple ecosystem services. Tree diversity is also an important determinant of the ecological stability or vulnerability of the forests against disturbances, such as insect outbreaks or pathogen epidemics. Forest management decisions regarding the tree species diversity are therefore at the very core of successful adaptation of forestry to climate change and for sustainable forest management to meet the energy and raw material needs of the circular bioeconomy. In this chapter, we focus on three strategies that have been suggested as measures for adapting the forest management to climate change and that have the potential to influence tree diversity in forests, viz. introduction of diversity using non-native tree species, assisted migration, or use of admixtures. We discuss the forest health risks of these strategies and some avenues that can help to mitigate these risks in future forest management.Peer reviewe

Control and management of Phytophthora damage in forestry-A systematic mapping study

17 Pág.Plant pathogens in the genus Phytophthora are a severe threat to forest plantations, ecosystems and tree nurseries. Especially in forests and natural ecosystems, there is a lack of effective measures to control and manage these pathogens. In this study, we conducted a systematic mapping review to collate evidence regarding the control and management of forest Phytophthora in different production settings and ecosystems. The study aimed to reveal possible knowledge gaps, thus guiding future research priorities. We extracted information from nine databases, limiting the search to studies published during the time period from January 2010 to December 2022. The articles were shared between three reviewers who classified the reports using a set of inclusion/exclusion criteria. A total of 561 articles were included and mapped in a database using pre-defined coding, and critically appraised for relevance and reliability. The analysis showed that biological or bio-based measures were the most studied interventions, followed by genetics or breeding programmes, whereas chemical and silvicultural management approaches were less studied. Most of the studies were conducted in Europe, North America, Australia and New Zealand. Phytophthora cinnamomi has been the most studied species followed by P. ramorum. We discuss the current knowledge gaps in the implementation of existing research, likely due to a lack of holistic understanding of the processes over time and space, and suggest future research that is needed to manage Phytophthora in forest ecosystems.This work was financially supported by the European Union's Horizon 2020 (H2020) Marie Skłodowska-Curie Actions Innovative Training Networks PROTECTA H2020-MSCA-ITN-2017 caLL, under grant agreement number 766048 (NLG). CR received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 845419. We acknowledge the kind contribution of Professor Steve Woodward and Maja Brus-Szkalej, who made valuable comments on an earlier version of this manuscript. We are grateful for the thoughtful reviews of two anonymous reviewers and the editor-in-chief, which helped improve this article.Peer reviewe