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International audience ; Plantation forestry in Zambia is based mainly on non-native Eucalyptus and Pinus species and constitutes an important component of the country's economy. The productivity of these plantations is, however, threatened by several factors, including fungal pathogens that reduce timber quality and cause tree mortality.* In this paper we present a review of diseases affecting plantation forestry and highlight factors that may favour their development and severity in the country.* Plantation health management in the country is seriously hampered by a general lack of information on pests and diseases affecting these plantations. In this regard, most research has been done more than 30 years ago, and very few pathogens have been identified to species level using modern identification techniques.* Recent surveys identified several previously unknown diseases of Eucalyptus spp. in the country, emphasizing the importance of renewed research on this topic. The impact of diseases associated with these pathogens has been exacerbated by poor plantation management, insufficient financial resources and lack of human capacity to deal with them.* Successful plantation management in Zambia will require increased and improved training of foresters regarding tree health issues, more effective quarantine, silvicultural practices, and importantly, the establishment of sound breeding and selection programmes. These will require considerable commitment from Government, commercial companies and research and educational organizations in the country.

South Africa is a country with very limited natural forest cover. Consequently, the timber and fibre needs of the country cannot be provided for from indigenous forest. It is largely for this reason that South Africa initially developed a highly productive plantation forest industry, which today makes a substantial contribution to the local economy. These plantations are based on non-native species of Eucalyptus, Pinus and Australian Acacia. In the early years of establishment, South African plantations were relatively free of pest and pathogen problems. But, over time, an increasing number of insects, fungi and bacteria have emerged as serious threats to the sustainability of the forestry industry. Numerous native pests and pathogens, especially insects, have adapted to these introduced tree species to cause damage or disease. The problem is compounded by the accidental introduction of non-native pests and pathogens, and this has been at a rapidly increasing rate over the past three decades. Some of these introduced pests and pathogens also threaten the fitness and even the survival of many indigenous South African tree species. Fortunately, South Africa has developed an impressive knowledge base and range of integrated management options to deal with these problems. This development was first driven by government programmes, and in more recent years by public–private partnerships between industry, universities and government. It is clear from the pattern of emergence of pests and pathogens in recent years that South Africa will deal with an increasing number of these problems and a continuously changing tree health environment. This requires robust investment in both quarantine and mitigation mechanisms to protect the country's biodiversity as well as to ensure the sustainability of its wood and fibre industries. SIGNIFICANCE : • This review about tree health in South Africa was in part inspired by the 2020 International Year of Plant Health. Plant health, and particularly tree health, is an important topic in ...

13 Pág. ; Mycoviruses are known to be difficult to cure in fungi but their spontaneous loss occurs commonly. The unexpected disappearance of mycoviruses can be explained by diverse reasons, from methodological procedures to biological events such as posttranscriptional silencing machinery. The long-term effects of a virus infection on the host organism have been well studied in the case of human viruses; however, the possible residual effect on a fungus after the degradation of a mycovirus is unknown. For that, this study analyses a possible residual effect on the transcriptome of the pathogenic fungus Fusarium circinatum after the loss of the mitovirus FcMV1. The mycovirus that previously infected the fungal isolate was not recovered after a 4-year storage period. Only 14 genes were determined as differentially expressed and were related to cell cycle regulation and amino acid metabolism. The results showed a slight acceleration in the metabolism of the host that had lost the mycovirus by the upregulation of the genes involved in essential functions for fungal development. The analysis also revealed a weak expression in the annotated genes of the RNA silencing machinery. To our knowledge, this is the first time that a potential residual effect on the host transcriptome caused by the past infection of a mycovirus is reported. ; This article is based upon the work 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) and project AGL2015-69370-R funded by MINECO (Spain). This study was made possible through the Interreg SUDOE project PLURIFOR "Transnational Plans for the Management of Forest Risks", and with the support of the Government of Cantabria (Spain). Research was supported by project PID2019-110459RB-I00 funded by MICINN (Spain) and FEDER (EU) budget as well as the project VA208P20 funded by JCYL (Spain) ; Peer reviewed

Brown spot needle blight (BSNB), a disease of pine trees caused by the fungus Lecanosticta acicola, has been known in Slovenia since 2008 and in Croatia since 1975. Recent outbreaks in Slovenia prompted this study to compare L. acicola populations in these two neighbouring European countries. Sixty‐nine isolates collected from three pine species (Pinus mugo, P. halepensis and P. nigra) were used to determine the phylogenetic relationships, genetic structure, and reproductive strategy of the pathogen. EF1‐α sequences showed that Slovenian and Croatian isolates share a common ancestry with individuals from central and northern Europe. Population structure analysis revealed four distinct population clusters of L. acicola in these two countries, generally corresponding to their respective geographic location and host. An unequal ratio of mating types and a low overall genetic diversity in the population indicated a strong influence of asexual reproduction. Although some of the oldest recorded European occurrences of BSNB are from Croatia, this study provided no evidence that the population studied in Croatia was the source of the sampled outbreaks in Slovenia. Recent outbreaks of L. acicola in Slovenia are most likely due to introductions from other, yet to be identified, sources. ; Figure S1. Delineated results of Evanno (Evanno et al., 2005) (left) and Puechmaille (Puechmaille, 2016) (right) methods for determining optimal number of K. ; Figure S2. structure bar plots representing K = 2 to K = 5, obtained from the Bayesian analysis of Lecanosticta acicola samples collected from Slovenia and Croatia. The percentage on the right represents the proportion of independent structure runs (30 in total) that correspond to the significantly similar clustering pattern (SSC > 0.9). The population codes correspond to the order of populations listed in Table 1. ; Figure S3. Value of Bayesian informative characters (BIC) versus the number of clusters. ; Table S1. Lecanosticta acicola isolates (ID) from Slovenia and Croatia ...

The world's forests have never been more threatened by invasions of exotic pests and pathogens, whose causes and impacts are reinforced by global change. However, forest entomologists and pathologists have, for too long, worked independently, used different concepts and proposed specific management methods without recognising parallels and synergies between their respective fields. Instead, we advocate increased collaboration between these two scientific communities to improve the long-term health of forests. Our arguments are that the pathways of entry of exotic pests and pathogens are often the same and that insects and fungi often coexist in the same affected trees. Innovative methods for preventing invasions, early detection and identification of non-native species, modelling of their impact and spread and prevention of damage by increasing the resistance of ecosystems can be shared for the management of both pests and diseases. We, therefore, make recommendations to foster this convergence, proposing in particular the development of interdisciplinary research programmes, the development of generic tools or methods for pest and pathogen management and capacity building for the education and training of students, managers, decision-makers and citizens concerned with forest health. ; The European Union's Horizon 2020 research and innovation programme ; http://neobiota.pensoft.net ; am2021 ; Biochemistry ; Forestry and Agricultural Biotechnology Institute (FABI) ; Genetics ; Microbiology and Plant Pathology

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 reviewed ; Publisher PDF