Search

8 Pág. Instituto de Ciencias Forestales (ICIFOR), Pathogen life history traits influence epidemic development and pathogen adaptive ability to interact with their hosts in different environments. Reduced traits variation may compromise pathogen evolutionary potential, which is particularly important for introduced pathogens. Fusarium circinatum (cause of pine pitch canker) is an invasive fungal pathogen in Europe, with current distribution restricted to forest stands of Pinus radiata and Pinus pinaster in northern Spain and Portugal. This study aimed to quantify pathogenic traits of Spanish isolates of F. circinatum, with two of the strains representing the two dominant haplotypes in the Spanish population. Disease severity was measured on P. radiata, analyzing the influence of temperature and moisture duration on infection as well as the influence of temperature on spore germination, sporulation, and mycelial growth. Results indicated that the isolate representing the most common haplotype caused more severe disease on P. radiata at 25 and 30°C compared with the second most common haplotype but caused less severe disease at 15°C. Spore germination was higher for the most common haplotype, which produced more spores at 20 and 25°C. The isolate showed hyphal melanization at 5°C, which has been associated with survival and may be important because no resting structures have been described for F. circinatum. Our study determined that longer moisture periods during infection result in more severe disease from 7 to 24 h, regardless of the isolate virulence. This is the first study on virulence of the most abundant haplotypes of F. circinatum in Spain as affected by temperatures and moisture., This research was supported by Ministerio de Economia y Competitividad (Subprograma de Proyectos de I+D orientado a los Recursos y Tecnologias Agrarias en coordinación con las Comunidades Autonomas) projects RTA 2013-00048-C03-01 and RTA 2017-00063-C04-01.

13 Pág. Instituto de Ciencias Forestales (ICIFOR), This study investigated the complex phenotypic and genetic response of Monterey pine (Pinus radiata) seedlings to co-infections by F. circinatum, the causal agent of pine pitch canker disease, and the oomycetes Phytophthora xcambivora and P. parvispora. Monterey pine seedlings were wound-inoculated with each single pathogen and with the combinations F. circinatum/P. xcambivora and F. circinatum/P. parvispora. Initially, seedlings inoculated only with F. circinatum showed less severe symptoms than seedlings co-inoculated or inoculated only with P. xcambivora or P. parvispora. However, 30 days post-inoculation (dpi), all inoculated seedlings, including those inoculated only with F. circinatum, showed severe symptoms with no significant differences among treatments. The transcriptomic profiles of three genes encoding pathogenesis-related proteins, i.e., chitinase (PR3), thaumatin-like protein (PR5), phenylalanine ammonia-lyase (PAL), and the pyruvate decarboxylase (PDC)-encoding gene were analyzed at various time intervals after inoculation. In seedlings inoculated with single pathogens, F. circinatum stimulated the up-regulation of all genes, while between the two oomycetes, only P. xcambivora induced significant up-regulations. In seedlings co-inoculated with F. circinatum and P.xcambivora or P. parvispora none of the genes showed a significant over-expression 4 dpi. In contrast, at 11 dpi, significant up-regulation was observed for PR5 in the combination F. circinatum/P.xcambivora and PDC in the combination F. circinatum/P. parvispora, thus suggesting a possible synergism of multiple infections in triggering this plant defense mechanism., This article is based upon the activity of COST Action FP1406 PINESTRENGTH (Pine Pitch Canker strategies for management of Gibberella circinata in greenhouses and forests) supported by COST (European Cooperation in Science and Technology); this research was funded by the University of Catania, Italy “Investigation of phytopathological problems of the main Sicilian productive contexts and eco-sustainable defense strategies (MEDIT-ECO)” “PiaCeRi-PIAno di inCEntivi per la Ricerca di Ateneo 2020-22 linea 2” “5A722192155”; by the project “Smart and innovative packaging, postharvest rot management and shipping of organic citrus fruit (BiOrangePack)” Partnership for Research and Innovation in the Mediterranea Area (PRIMA)-H2020 (E69C20000130001). F.A. has been granted a Ph.D. fellowship “Scienze Agrarie, Alimentari, Forestali e Ambientali—XXXIII cycle”, University of Palermo.

Producción Científica, Fusarium circinatum is a harmful pathogenic fungus mostly attacking Pinus species and also Pseudotsuga menziesii, causing cankers in trees of all ages, damping-of in seedlings, and mortality in cuttings and mother plants for clonal production. This fungus is listed as a quarantine pest in several parts of the world and the trade of potentially contaminated pine material such as cuttings, seedlings or seeds is restricted in order to prevent its spread to disease-free areas. Inspection of plant material often relies on DNA testing and several conventional or real-time PCR based tests targeting F. circinatum are available in the literature. In this work, an international collaborative study joined 23 partners to assess the transferability and the performance of nine molecular protocols, using a wide panel of DNA from 71 representative strains of F. circinatum and related Fusarium species. Diagnostic sensitivity, specifcity and accuracy of the nine protocols all reached values >80%, and the diagnostic specifcity was the only parameter difering signifcantly between protocols.The rates of false positives and of false negatives were computed and only the false positive rates difered signifcantly, ranging from 3.0% to 17.3%.The diference between protocols for some ofthe performance values were mainly due to cross-reactions with DNA from non-target species, which were either not tested or documented in the original articles. Considering that participating laboratories were free to use their own reagents and equipment, this study demonstrated that the diagnostic protocols for F. circinatum were not easily transferable to endusers. More generally, our results suggest that the use of protocols using conventional or real-time PCR outside their initial development and validation conditions should require careful characterization of the performance data priorto use under modifed conditions (i.e. reagents and equipment). Suggestions to improve the transfer are proposed., European Cooperation in Science and Technology (COST Action FP1406 PINESTRENGTH), Estonian Science Foundation (grants PSG136 and IUT21-04), Centro de Estudios do Ambiente e do Mar (CESAM) (projects UID/AMB/50017/2013 and POCI-01- 0145- FEDER-007638), Slovenian Research Agency (project P4-0107)

Pine pitch canker (PPC), caused by Fusarium circinatum, affects Pinus species worldwide. Although no effective solutions have yet been found to control it, there is a growing interest in using biological control agents (BCA) such as Trichoderma to avoid the application of chemical‐based products. Using species with an increasing level of susceptibility to PPC (Pinus pinea, Pinus pinaster and Pinus radiata), this study aimed to evaluate the effect of Trichoderma viride pre‐inoculation on disease development, assessing several physiological and hormonal parameters. A 2‐week period elapsed between T. viride and F. circinatum inoculation. Sampling for each species was performed independently when at least 50% of the plants of one of the inoculated groups developed disease symptoms. Fusarium circinatum infection reduced water status and photosynthesis, but increased proline, abscisic acid and jasmonic acid concentrations in plants of P. radiata and P. pinaster with symptoms; while in P. pinea water relations were maintained and anthocyanin accumulation occurred in the presence of F. circinatum. In P. radiata, T. viride pre‐inoculation accelerated disease progression, with some PPC‐induced responses augmented (decreased water potential and photosynthesis; increased substomatal CO2 concentration) and novel changes not found in seedlings inoculated exclusively with F. circinatum (increased electrolyte leakage and salicylic acid; decreased relative water content). This suggests that T. viride may be initially recognized as an invading organism, subverting the plant defence mechanisms for successful root colonization. If seedlings are not allowed to recover from this state, pathogen infection may thus be facilitated, highlighting the importance of application timing in BCA strategies.

In this study, the effects of hot water (HWT), hydrogen peroxide and fungicides on the incidence of Fusarium circinatum on artificially inoculated Pinus radiata seeds were evaluated. Fifteen commercial fungicide formulations were screened in vitro for inhibitory activity on mycelial growth and conidial germination of F. circinatum. With half-maximal effective concentration (EC50) lower than 0.5 ppm, fluazinam, imazalil and tebuconazole were the most effective fungicides on mycelial growth, while captan, mancozeb or pyraclostrobin were the most effective (EC50 < 0.3 ppm) on conidial germination. Based on the results obtained, imazalil, fluazinam, mancozeb and pyraclostrobin were selected for further testing. The effects of HWT, hydrogen peroxide and fungicide treatments on seed emergence and the incidence of F. circinatum were assessed. Seed treatments with fungicides prior to sowing were less effective and inconsistent in reducing the incidence of F. circinatum on seedlings. In contrast, hot water and hydrogen peroxide treatments significantly reduced F. circinatum contamination on P. radiata seeds with an overall disease incidence lower than 0.8% on seedlings. Furthermore, subsequent application of fungicides on seedlings did not improve the effectiveness of HWT. These results, therefore, suggest that hot water is a better alternative to hydrogen peroxide and fungicides as Pinus seed treatment against F. circinatum and could easily be implemented as standard in commercial nurseries to control the spread of the pitch canker disease., This research was financially supported by the Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) and Ministerio de Medio Ambiente y Medio Rural y Marino (MARM). Monica Berbegal was a contract holder of the 'Campus de Excelencia Internacional' programme of the Universidad Politecnica de Valencia. We thank Antonio Ramon for technical assistance.

Ponencia presentada en el Congreso IUFRO 2013 WP 7.02.02 Foliage Shoot and Stems Diseases: Biosecurity in Natural Forests and Plantations, Genomics and Biotechnology for Biosecurity and Forestry. Celebrado en Brno y Černa Hora (Reublica Checa) durante los días 20-25 de mayo de 2013.

Hot water treatments (HWTs) were evaluated for their ability to reduce the incidence of Fusarium circinatum on Pinus radiata seeds. The effect of HWTs on conidial germination and mycelial growth of F. circinatum isolates representative of both mating types (MAT-1 and MAT-2) was determined by incubating conidial suspensions and agar plugs with mycelium in a hot water bath. The percentages of conidial germination and mycelial growth relative to the non-treated control decreased with increasing temperature and time of HWTs. MAT-2 isolates were more sensitive to HWTs than those of MAT-1, and no germination or mycelial growth of MAT-2 isolates was observed for temperatures above 50°C. The effect of HWT on P. radiata seed germination was also evaluated. The decrease in the percentage of seed germination compared with the non-treated seeds was always below 30 per cent for treatment temperatures, This research was financially supported by Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) and Ministerio de Medio Ambiente y Medio Rural y Marino (MARM). M. Berbegal was a contract holder of the 'Campus de Excelencia Internacional' programme of the Universidad Politecnica de Valencia.

The Panel on Plant Health was asked to provide a risk assessment for Gibberella circinata Nirenberg and O'Donnell, for the EU territory, and to identify and evaluate effectiveness of risk management options in reducing the risk posed by the organism. G. circinata is presently not listed in Council Directive 2000/29/EC. Outbreaks of the organism have been reported in EU (in Spain, Italy, France and Portugal). The risk assessment indicates that, in parts of the European Union, there is risk of pitch canker affecting the host species (pine and Douglas‐fir). Entry into and spread within the European Union are considered very likely. The organism has a very high potential for establishment. The following pathways for entry have been identified: contaminated seed and other propagation material, different forms of wood material, plant material for decorative purposes, soil and growing substrates, natural means (wind, wind‐blown rain, insects and other animals carrying spores) and human activities. Based on host distribution and climatic conditions, the potentially endangered areas include wide areas of central and northern Portugal, northern and eastern Spain, south and coastal areas of France, coastal areas of Italy and parts of the coastal areas of Greece. In these areas, pine forests, including plantations and native forest, cover over 10 million hectares. Host species are also widely used as ornamentals. The potential consequences of pitch canker in the endangered areas are considered massive. At present there is no single means of controlling pitch canker. Consequently, an integrated disease management approach, which combines appropriate nursery and silvicultural practices, should be used to reduce the impact of the disease. The current legislation, including the provisional emergency measures (Commission Decision 2007/433/EC), is aimed at limiting the introduction of the organism but it may have only a limited effect on its spread.