Diseases of Eucalypts in Paraguay and First Report of Teratosphaeria zuluensis from South America

Background and objectives: The global forest economy is threatened by eucalypt pathogens which are often latent or cryptic species that escape common quarantine and detection methods. Plantation forestry using eucalypts is of considerable importance to Paraguay, but knowledge regarding the pests and diseases affecting these plantations is limited. This study identified fungal diseases present in these plantations. Materials and Methods: We surveyed eucalypt plantations in four provinces in Paraguay and collected material from diseased trees for identification of the causal agents. The samples were analyzed using a combination of morphological and molecular methods. Results: Diseases encountered included Botryosphaeria stem canker, Calonectria leaf blight, Chrysoporthe stem canker, myrtle/eucalypt rust, Coniella leaf spot, heartwood rot and Teratosphaeria stem canker. Contrary to expectations, the causal agent of Teratosphaeria stem canker was identified as Teratosphaeria zuluensis (M.J. Wingf., Crous & T.A. Cout.) M.J. Wingf. & Crous and not Teratosphaeria gauchensis (M.-N. Cortinas, Crous & M.J. Wingf.) M.J. Wingf. & Crous, that is commonly documented for the South American region. Conclusions: This study updates the knowledge on forest fungal pathogens in Paraguayan eucalypt plantations and is the first report of T. zuluensis in Paraguay and in South America

Celoporthe dispersa gen. et sp. nov. from native Myrtales in South Africa

In a survey for Cryphonectria and Chrysoporthe species on Myrtales in South Africa, a fungus resembling the stem canker pathogen Chrysoporthe austroafricana was collected from native Syzygium cordatum near Tzaneen (Limpopo Province), Heteropyxis canescens near Lydenburg (Mpumalanga Province) and exotic Tibouchina granulosa in Durban (KwaZulu-Natal Province). The fungus was associated with dying branches and stems on S. cordatum, H. canescens and T. granulosa. However, morphological differences were detected between the unknown fungus from these three hosts and known species of Chrysoporthe. The aim of this study was to characterise the fungus using DNA sequence comparisons and morphological features. Pathogenicity tests were also conducted to assess its virulence on Eucalyptus (ZG 14 clones), H. natalensis and T. granulosa. Plants of H. canescens were not available for inoculation. Results showed distinct morphological differences between the unknown fungus and Chrysoporthe spp. Phylogenetic analysis showed that isolates reside in a clade separate from Chrysoporthe and other related genera. Celoporthe dispersa gen. et sp. nov. is, therefore, described to accommodate this fungus. Pathogenicity tests showed that C. dispersa is not pathogenic to H. natalensis, but that it is a potential pathogen of Eucalyptus and Tibouchina spp

First report of Teratosphaeria zuluensis causing stem canker of Eucalyptus grandis in Uganda

Teratosphaeria stem canker is one of the most important diseases to have emerged on nonnative plantation-grown Eucalyptus trees globally. In 2012, Eucalyptus grandis trees with typical Teratosphaeria stem canker symptoms were observed in Uganda. Multi-gene sequence analyses of isolates made from these cankers led to the identification of two species of Teratosphaeria on these trees. These were T. gauchensis, previously recorded in Uganda and T. zuluensis. This study represents the first report of T. zuluensis in Uganda. Furthermore, this is the first report of the co-occurrence of T. zuluensis and T. gauchensis in a single area.National Research Foundation (NRF), members of the Tree Protection Cooperative Programme (TPCP) and the THRIP Initiative of the Department of Trade and Industry, South Africa.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0329hb201

Diseases on Eucalyptus species in Zimbabwean plantations and woodlots

Zimbabwe embarked on planting Eucalyptus species in the early 1900’s. Based on a robust breeding programme, it has become a major source of seed for other countries in and outside Africa. Tree health surveys conducted on Eucalyptus in some east and southern Africa countries over the past two decades have revealed several important fungal diseases that were previously not known in the region, but little is known regarding these problems in Zimbabwe. The aim of this study was to identify important eucalypt diseases across Zimbabwe’s agro-climatic regions. Morphological characteristics and DNA sequence data were used to identify pathogens collected to species level. Widespread stem canker diseases, caused by species belonging to the Botryosphaeriaceae and Teratosphaeriaceae, and leaf spot diseases caused by fungi in the Capnodiales, were identified. Armillaria root and stem rot was restricted to a single site in the Eastern Highlands. Fungi that could cause canker or blue stain of timber were isolated from recently harvested stumps and included species of Ceratocystis and Ophiostoma. This study is the first to identify Eucalyptus pathogens to species level in Zimbabwe and we report for the first time the presence of the stem canker pathogen T.gauchensis in southern Africa. The results will provide a foundation for the formulation of future disease management strategies in the country.National Research Foundation (NRF), members of the Tree Protection Cooperative Programme (TPCP) and the THRIP Initiative of the Department of Trade and Industry, South Africa.http://www.tandfonline.com/loi/tsed202016-06-30hb201

Population structure of Chrysoporthe austroafricana in southern Africa determined using Vegetative Compatibility Groups (VCGs)

Chrysoporthe austroafricana is one of the most damaging pathogens of Eucalyptus trees in southern Africa. It also occurs on non-native Tibouchina granulosa trees and native Syzygium species. Additional isolates of the pathogen from previously unstudied countries in the region have become available from survey studies. The aim of this study was to use VCGs to consider the diversity in populations of isolates collected in various countries in southern Africa (Malawi, Mozambique, Namibia, South Africa and Zambia) and from different hosts. We also wanted to determine whether there are shared VCGs among these countries and hosts in southern Africa and establish a VCG tester strain data base. Results showed a high diversity amongst isolates from different countries and hosts, but suggested little movement of VCGs among countries or hosts based on the available isolates. A total of 108 VCG tester strains were identified for southern Africa.The University of Pretoria (UP), National Research Foundation (NRF), Forestry and Agricultural Biotechnology Institute (FABI) and Tree Protection Cooperative Program (TPCP).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0329hb2016Microbiology and Plant Patholog

Selective feeding behaviors illuminate patterns of sap beetle associations with ophiostomatoid fungi

Sap beetles (Coleoptera: Nitidulidae) are commonly associated with ophiostomatoid fungi, especially those belonging to the family Ceratocystidaceae. This coexistence of insects and fungi, usually on tree wounds, offers the ophiostomatoid fungi an effective means of dispersal. The selective advantage of this association to sap beetles is, however, confounded by the versatile life history strategies of these insects. In this study, we complemented field observations with rearing and feeding behavior experiments in the laboratory, to investigate the symbiology of interactions between sap beetles and co-occurring fungi, from the insect perspective. We determined that all predominant sap beetle vectors of the Ceratocystidaceae in a natural woodland feed on and use the mycelial mats of these fungi to nurse their offspring in tree wounds. When reared on fungal cultures in the laboratory, several of these insects successfully completed their life cycle. We were able to maintain Carpophilus hemipterus on this exclusive fungal diet over several generations. The feeding preference of this insect was generally consistent with the patterns of its fungal associations in the field as previously reported. There also appeared to be a correlation between the attractiveness of Ca. hemipterus to various fungi and its fitness benefits from feeding on these fungi. Overall, our results suggest that, from their partnership with ophiostomatoid fungi, sap beetles benefit from essential nutritional supplementation, enabling them to survive in saproxyly in woodland ecosystems.The DST/NRF Center of Excellence in Tree Health Biotechnology (CTHB) of South Africa.http://link.springer.com/journal/13199hj2021Forestry and Agricultural Biotechnology Institute (FABI)Plant Production and Soil Scienc

Phylogenetic species recognition and hybridisation in Lasiodiplodia : a case study on species from baobabs

Lasiodiplodia species (Botryosphaeriaceae, Ascomycota) infect a wide range of typically woody plants on which they are associated with many different disease symptoms. In this study, we determined the identity of Lasiodiplodia isolates obtained from baobab (Adansonia species) trees in Africa and reviewed the molecular markers used to describe Lasiodiplodia species. Publicly available and newly produced sequence data for some of the type strains of Lasiodiplodia species showed incongruence amongst phylogenies of five nuclear loci. We conclude that several of the previously described Lasiodiplodia species are hybrids of other species. Isolates from baobab trees in Africa included nine species of Lasiodiplodia and two hybrid species. Inoculation trials with the most common Lasiodiplodia species collected from these trees produced significant lesions on young baobab trees. There was also variation in aggressiveness amongst isolates from the same species. The apparently widespread tendency of Lasiodiplodia species to hybridise demands that phylogenies from multiple loci (more than two and preferably four or more) are compared for congruence prior to new species being described. This will avoid hybrids being incorrectly described as new taxa, as has clearly occurred in the past.Members of the Tree Protection Co-operative Programme (TPCP), the NRF-DST Centre of Excellence in Tree Health Biotechnology (CTHB), and the University of Pretoria, South Africa.http://www.elsevier.com/locate/funbio2018-04-30Plant ScienceForestry and Agricultural Biotechnology Institute (FABI)Genetic

Sporendocladia bactrospora associated with wounds on native broadleaved trees in Norway and Sweden

A survey to identify ophiostomatoid fungi that infect wounds on native Norwegian and Swedish broadleaved trees was undertaken during summer 2004. A fungus resembling a species of Sporendocladia was commonly isolated from the exposed cambium and inner bark of wounds. Morphological examination and comparisons of DNA sequence data for the ITS and 5.8S regions of the rRNA gene region led to its identification as Sporendocladia bactrospora. Pathogenicity trials on young Populus tremula and Betula pubescens trees showed that S. bactrospora is capable of causing lesions on these trees. There have been few previous reports of S. bactrospora, and in most cases, these have been as saprophytes on wood. In contrast, results of this study show that it is a common inhabitant of freshly made wounds on native broadleaved trees in Scandinavia, and it appears to contribute to staining of wood.Norwegian Research Council (152266/V10)http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0329hb201