Irene Barnes

University of Pretoria | UP · Forestry and Agricultural Biotechnology Institute (FABI)

Dothistroma needle blight (DNB) caused by Dothistroma septosporum is one of the most important needle diseases of Pinus spp., especially in Southern Hemisphere plantations. In Colombia, the pathogen has caused severe outbreaks in plantations of Pinus tecunumanii of the low elevation population (LE). Currently, management strategies suffer from a la...

Araucaria araucana is an ancient conifer, native to the mountain ranges in Chile and Argentina. These trees host a large number of organisms, mainly insects, strongly or even exclusively associated with them. The recent emergence of a novel canker disease on A. araucana has emphasised the importance of fungi associated with these iconic trees and h...

European forests are threatened by increasing numbers of invasive pests and pathogens. Over the past century, Lecanosticta acicola, a foliar pathogen predominantly of Pinus spp., has expanded its range globally, and is increasing in impact. Lecanosticta acicola causes brown spot needle blight, resulting in premature defoliation, reduced growth, and...

Fulvia fulva and Dothistroma septosporum are closely related apoplastic pathogens with similar lifestyles but different hosts: F. fulva is a pathogen of tomato, whilst D. septosporum is a pathogen of pine trees. In 2012, the first genome sequences of these pathogens were published, with F. fulva and D. septosporum having highly fragmented and near-...

The nematode Deladenus siricidicola is used for the biocontrol of the invasive woodwasp, Sirex noctilio, that infests Pinus globally. In New Zealand, D. siricidicola was accidentally introduced along with S. noctilio, after which its potential for biological control was realized in the 1960s. Additional strains of the nematode were collected from a...

The Coryneliaceae is a relatively small family of mainly pathogenic fungi occurring on a diversity of hosts with a wide global distribution. Members of the family are recognized by their black, upright and elongated ascomata. Historically, the taxonomy of this group was mainly based on morphological characters, but in more recent years, DNA sequenc...

The monkey puzzle tree or pewen (Araucaria araucana), is an ancient conifer endemic to the Chilean and Argentinian mountain ranges. These trees live up to a thousand years, are slow growing and have both a sacred and economic relevance to indigenous communities in both countries. Between 2015 and 2016, an unrecorded disease causing severe crown die...

The genus Pewenomyces was recently described based on Pewenomyces kutranfy, a fungal pathogen that causes cankers on branches and stems of Araucaria araucana in Chile. This genus resides in the Coryneliaceae, a relatively small Family, and its morphology resembles those of species in the closely related genera Caliciopsis and Hypsotheca. During the...

Purpose of Review The Araucariaceae is a family of ancient conifers containing iconic tree species from diverse parts of the world. Thirty-eight extant species are present in three genera. Extensive reduction of natural populations has occurred for many species of Araucariaceae, largely due to anthropogenic disturbances. This has occurred to the ex...

Purpose of Review The Araucariaceae is a family of ancient conifers containing iconic tree species from diverse parts of the world. Thirty-eight extant species are present in three genera. Extensive reduction of natural populations has occurred for many species of Araucariaceae, largely due to anthropogenic disturbances. This has occurred to the...

The genus Calonectria includes many aggressive plant pathogens causing diseases on various agricultural crops as well as forestry and ornamental tree species. Some species have been accidentally introduced into new environments via international trade of putatively asymptomatic plant germplasm or contaminated soil, resulting in significant economic...

Brown spot needle blight (BSNB), caused by the fungal pathogen Lecanosticta acicola, is a well-known disease of Pinus species in several Northern Hemisphere countries. In the Southern Hemisphere, this disease has been reported only in Colombia and, apart from a single report of severe defoliation of Pinus radiata plantations in the early 1980s, has...

Species in the Ceratocystis manginecans complex are important fungal pathogens of plantation trees globally. The most important hosts include species of Eucalyptus, Acacia, Mangifera, and Punica. Despite their relevance and widespread occurrence, little is known regarding their population genetics and how this might relate to their host association...

Dothistroma pini is one of two pathogens causing the foliar disease of pines: Dothistroma needle blight (DNB). The species was re‐defined in 2004 and subsequently recorded in several European countries. In Slovakia, the first report of the pathogen was in 2013. In this study, the population structure, genetic diversity and reproductive mode of 105...

Stem canker disease of Araucaria araucana in Chile, caused by the newly described fungal species, Pewenomyces kutranfy. Photograph: Rodrigo Ahumada. See 70, 778–792.

Needle blights are serious needle fungal diseases affecting pines both in natural and productive forests. Among needle blight agents, the ascomycetes Lecanosticta acicola, Dothistroma pini and D. septosporum are of particular concern. These pathogens need specific, fast and accurate diagnostics since they are regulated species in many countries and...

Several species in the Euwallacea fornicatus complex have emerged as important pests of woody plants globally, particularly in habitats where they are invasive aliens. These beetles live in obligate symbioses with fungi in the genus Fusarium. In this study, we identified Euwallacea spp. and their fungal mutualists that have emerged as pests of plan...

Araucaria araucana, (commonly referred to as Araucaria, Pewen or monkey puzzle tree) is an ancient conifer endemic to the Chilean and Argentinean mountain ranges where it has a sacred relevance to indigenous communities. During 2016, a serious disease was noticed on trees of all ages in most of the natural distribution of this iconic tree. Four are...

Dothistroma septosporum, the primary causal agent of Dothistroma needle blight, is one of the most significant foliar pathogens of pine worldwide. Its wide host and environmental ranges have led to its global success as a pathogen and severe economic damage to pine forests in many regions. This comprehensive global population study elucidated the h...

Cercospora zeina is a causal pathogen of gray leaf spot (GLS) disease of maize in Africa. This fungal pathogen exhibits a high genetic diversity in South Africa. However, little is known about the pathogen’s population structure in the rest of Africa. In this study, we aimed to assess the diversity and gene flow of the pathogen between major maize...

In 2014, a new and serious leaf and shoot disease of unknown aetiology appeared in Eucalyptus plantations of North Sumatra, Indonesia. The disease is characterised by black necrotic spots that initially appear on young leaves and petioles, which become scab‐like as the lesions age. Infected trees respond to infection by producing shoots with small...

The genus Calonectria includes many important plant pathogens with a wide global distribution. In order to better understand the reproductive biology of these fungi, we characterised the structure of the mating type locus and flanking genes using the genome sequences for seven Calonectria species. Primers to amplify the mating type genes in other s...

Ceratocystis accommodates many important pathogens of agricultural crops and woody plants. Ceratocystis fimbriata , the type species of the genus is based on a type that is unsuitable for a precise application and interpretation of the species. This is because no culture or DNA data exist for the type specimen. The aim of this study was to select a...

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. Previously (Geiser et al. 2013; Phytopathology 103:400-408. 2013), the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agr...

The fungal pathogen, Calonectria (Ca.) pauciramosa, has caused serious diseases of many important plants worldwide. Understanding the genetic diversity and mating type distribution of this pathogen provides an essential step towards the development of disease control measures. In this study, we designed 15 polymorphic microsatellite markers using g...

Austropuccinia psidii, cause of myrtle rust, has spread globally where Myrtaceae occur. Multiple strains of A. psidii have been identified, including a unique strain found only in South Africa. The South African strain is a biosecurity concern for species of Myrtaceae worldwide. This is because preliminary testing of South African Myrtaceae suggest...

Many current tree improvement programs are incorporating assisted gene flow strategies to match reforestation efforts with future climates. This is the case for the lodgepole pine (Pinus contorta var. latifolia), the most extensively planted tree in western Canada. Knowledge of the structure and origin of pathogen populations associated with this t...

A historical outbreak of needle blight disease was recorded during 2018 to 2019 in plantations of Pinus radiata and Pinus nigra in the North of Spain. The main pathogens involved in this historical outbreak were identified as Lecanosticta acicola and Dothistroma septosporum. Recently, a variety of tree species in three arboreta planted between 2011...

Coniothyrium stem canker, caused by Teratos�phaeria zuluensis, is one of the most important diseases of plantation-grown Eucalyptus trees in tropical and sub�tropical areas of the world. Previous research on the population structure of T. zuluensis in China, Malawi and South Africa has suggested that T. zuluensis in these countries had independent...

Gray leaf spot (GLS) disease is a major foliar disease of maize, whose causal pathogen is Cercospora zeina Crous & U. Braun. Cercospora zeina is reported to be a highly diverse pathogen in maize producing countries globally because of sexual recombination and persistent gene flow. However, these reports are based on analysis of a few isolates, popu...

Pewen or the Monkey Puzzle tree (Araucaria araucana) is an ancient conifer endemic to the mountain ranges from Chile and Argentina. Its distribution is limited to small populations in the south-central region of the Andes mountain range and Chilean’s coastal range, where it is of cultural and economic importance to the indigenous people of the regi...

Ceratocystis fimbriata is a host specific fungal pathogen of sweet potato (Ipomoea batatas). The closely related species, C. manginecans, is an important pathogen of trees (e.g. Acacia mangium and Mangifera indica) but has never been isolated from tuber crops. The genetic factors that determine the host range and host specificity of these species h...

Wilt and death of an E. grandis × E. urophylla variety was recently observed in the Zululand region of KwaZulu- Natal, South Africa. Symptoms on the dying trees included a streaking pattern of discolouration in the sapwood and cambium of stems and roots. A fungus resembling a Ceratocystis sp. was consistently found sporulating on diseased material...

Non-native Acacia plantations in Indonesia were first reported to be infested by a native ambrosia beetle species, identified as Euwallacea fornicatus in 1993. Recently the level of infestation in these plantations by ambrosia beetles has steadily increased. The recent redefinition of the taxonomic parameters of the Euwallacea fornicatus species co...

One of the main threats to forests in the Anthropocene are novel or altered interactions among trees, insects and fungi. To critically assess the contemporary research on bark beetles, their associated fungi, and their relationships with trees, the international Bark Beetle Mycobiome research coordination network has been formed. The network compri...

Background: The taxonomic history of Ceratocystis, a genus in the Ceratocystidaceae, has been beset with questions and debate. This is due to many of the commonly used species recognition concepts (e.g., morphological and biological species concepts) providing different bases for interpretation of taxonomic boundaries. Species delineation in Cerat...

Austropuccinia psidii is a rust fungus that has expanded its known geographic distribution and host range on Myrtaceae. Invasions by rust fungi are often caused by asexual urediniospores that give rise to populations with low genotypic diversity. Recently it was shown that basidiospores, the gametic spores of A. psidii, were able to infect species...

The Cryphonectriaceae (Diaporthales, Ascomycota) is an important family of fungi including endophytes and pathogens. These fungi cause cankers on trees and can shift hosts between genera and families in the Myrtales. They represent an understudied group in Southeast Asia, where species of Eucalyptus are grown for plantation forestry. Cankers on spe...

The largest impact of needle diseases in the recorded history of Pinus radiata and Pinus nigra plantations in the North of Spain, was from 2018 to 2019. The severity of the disease has led to a serious reconsideration of forest management in the area. The main pathogens involved in this historical outbreak were Lecanosticta acicola and Dothistroma...

Draft genomes of the fungal species Fusarium xylarioides, Teratosphaeria gauchensis and T. zuluensis are presented. In addition an annotation of the genome of Ceratocystis fimbriata is presented. Overall these genomes provide a valuable resource for understanding the molecular processes underlying pathogenicity and potential management strategies o...

The detrimental effect of fungal pathogens on forest trees is an increasingly important problem that has implications for the health of our planet. Despite this, the study of molecular plant-microbe interactions in forest trees is in its infancy, and very little is known about the roles of effector molecules from forest pathogens. Dothistroma septo...

Lecanosticta acicola causes brown spot needle blight (BSNB) of Pinus species. The pathogen occurs mostly in the Northern Hemisphere but has also been reported in Central America and Colombia. BSNB can lead to stunted growth and tree mortality, and has resulted in severe damage to pine plantations in the past. There have been increasingly frequent n...

Lecanosticta acicola causes the disease known as brown spot needle blight (BSNB), on Pinus species. The pathogen is thought to have a Central American centre of origin. This was based on the morphological variation between isolates believed to represent L. acicola from native Pinus spp. Two species of Lecanosticta, L. brevispora and L. guatemalensi...

Some species of Ceratocystis display strong host specificity, such as C. fimbriata sensu stricto that is restricted to sweet potato (Ipomoea batatas) as host. In contrast, the closely related C. manginecans, infects Acacia mangium and Mangifera indica but is not pathogenic to I. batatas. Despite the economic importance of these fungi, knowledge reg...

Dothistroma needle blight is one of the most devastating pine tree diseases worldwide. New and emerging epidemics have been frequent over the last 25 years, particularly in the Northern Hemisphere, where they are in part associated with changing weather patterns. One of the main Dothistroma needle blight pathogens, Dothistroma septosporum, has a gl...

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 (P...

The myrtle rust pathogen, Austropuccinia psidii, was recently detected in New Zealand and Singapore. We used microsatellite markers to identify the strain of A. psidii that caused these incursions. Our results show that the pandemic strain of the pathogen caused outbreaks in both New Zealand and Singapore.

Vietnam and Indonesia have rapidly growing and extensive plantation forestry programs, especially of Acacia spp. and Eucalyptus spp. As these plantations expand, the threat from pests and diseases also increases. Calonectria species are among those pathogens causing diseases of trees in plantations and nurseries in these countries. Extensive survey...

The native ‘ōhi’a lehua (Metrosideros polymorpha) has cultural, biological and ecological significance to Hawai’i, but it is seriously threatened by a disease commonly referred to as rapid ‘ōhi’a death (ROD). Preliminary investigations showed that a Ceratocystis species similar to C. fimbriata s.lat. was the cause of the disease. In this study, we...

The ascomycete genus Huntiella (Microascales) has a cosmopolitan distribution and occurs on a wide range of woody plants. Little is known regarding the identity, diversity, origin, or impact of these fungi in China. Recently, isolates of Huntiella spp. were collected from stumps of freshly felled trees or wounds on plantation-grown Eucalyptus in Gu...

Deladenus siricidicola is a parasite nematode of the woodwasp Sirex noctilio, which is invasive in the Southern Hemisphere, where it infests and kills pine trees. In New Zealand, D. siricidicola was accidentally introduced along with S. noctilio. In Australia, as in other Southern Hemisphere countries, D. siricidicola has been introduced deliberate...

Cylindrocladiella spp. are widely distributed especially in tropical and sub-tropical regions, where they are mainly known as saprobes although some species are plant pathogens. Very little is known about these fungi in South-East Asia. The aim of this study was to identify a collection of Cylindrocladiella isolates from soils collected in forest n...

Figure S2. Phylogenetic tree based on maximum likelihood (ML) analysis of tef1 sequence alignments

Figure S1. Phylogenetic tree based on maximum likelihood (ML) analysis of his3 sequence alignments

Figure S3. Phylogenetic tree based on maximum likelihood (ML) analysis of tub2 sequence alignments

Figure S4. Phylogenetic tree based on maximum likelihood (ML) analysis of ITS sequence alignments

Ceratocystis fimbriata is a fungal plant pathogen that causes black rot on Ipomoea batatas. Based on inoculation studies on numerous tree species, the pathogen is known to be host specific. The closely related species, Ceratocystis manginecans, causes severe wilt on a broad range of tree hosts, including Mangifera indica, Acacia mangium and other l...

The Ascomycete genus Ceratocystis has a broad geographic distribution and includes pathogens of a wide range of mostly woody hosts. Black rot of Colocasia esculenta (taro), a popular cultivated root crop in China, is caused by a species of Ceratocystis broadly treated as C. fimbriata sensu lato. Recently, isolates of Ceratocystis were obtained from...

Diseases caused by species of Calonectria (Ca.) represent a serious threat to the growth and sustainability of Eucalyptus plantations in China. Symptoms caused by these fungi mainly include leaf blight on trees in plantations and rotting of stems and leaves in nurseries. Extensive surveys have recently been conducted where Calonectria species were...

Dothistroma septosporum, a notorious pine needle pathogen with an unknown historical geographic origin and poorly known distribution pathways, is nowadays found almost in all areas inhabited by pines (Pinus spp.). The main aim of this study was to determine the relationship between North European and East Asian populations. In total, 238 Eurasian D...

Biological invasions in forests are growing in number and importance globally. The best studied examples are those caused by plants and animals, including insects. In contrast, forest invasions caused by microbes, including fungi, have received much lower levels of attention, particularly in the invasion biology literature. This can at least to som...

Associations between fungal tree pathogens and insects have been recognized for at least 100 years. An important group of these fungi, termed ‘ophiostomatoid fungi’ on account of their morphological similarity, are represented by genera in the families Ceratocystidaceae and Ophiostomataceae. Associations between these fungi, tree-colonizing insects...

The rust fungus Austropuccinia psidii has spread globally and naturalized in areas with naïve species of Myrtaceae. Previous studies have revealed multiple strains of A. psidii within South America and two strains outside of its native range. The rust spreads by wind-borne mitotic urediniospores, which are the dominant spore stage. Teliospores and...

Fungal secondary metabolites have many important biological roles and some, like the toxic polyketide aflatoxin, have been intensively studied at the genetic level. Complete sets of polyketide synthase (PKS) genes can now be identified in fungal pathogens by whole genome sequencing and studied in order to predict the biosynthetic potential of those...

The rust fungus Austropuccinia psidii was recently reported from ornamental Corymbia citriodora and plantations of Eucalyptus in Colombia. It is unknown whether the genotypic diversity of the pathogen in Colombia reflects that of other countries in South America or if unique genotypes occur. Multilocus genotypes (MLG) were determined for collection...

Genera of Phytopathogenic Fungi (GOPHY) is introduced as a new series of publications in order to provide a stable platform for the taxonomy of phytopathogenic fungi. This first paper focuses on 21 genera of phytopathogenic fungi: Bipolaris, Boeremia, Calonectria, Ceratocystis, Cladosporium, Colletotrichum, Coniella, Curvularia, Monilinia, Neofabra...

Cercospora zeina, Population genetics, Farming systems, Microsatellite markers

Ceratocystis tsitsikammensis was first isolated from bark harvesting wounds on two indigenous tree species in the Afromontane forests of the Western Cape Province of South Africa. Inoculation studies indicated that it is a potential pathogen of native Rapanea melanophloeos trees. In this study, we investigated the distribution, ecology and biology...

The rust pathogen, Puccinia psidii, was first detected in South Africa in 2013 on a single non-native ornamental Myrtus communis tree. This prompted surveys of the country to determine its geographic distribution and host range. Previously developed microsatellite markers where used to characterize the genetic diversity of P. psidii isolates collec...

Dothistroma needle blight (DNB) caused by Dothistroma septosporum and Dothistroma pini is a damaging disease of pine in many countries. The disease led to the abandonment of planting susceptible Pinus species in parts of Africa, Asia, Australasia, Europe and North America. Although the disease can be effectively controlled using copper fungicides,...

Dothistroma needle blight (DNB) is one of the most devastating needle diseases on Pinus spp. worldwide. Ever since the description of the causal agent of the disease in Europe in 1911 as Cytosporina septospora, and independently in the USA in 1941 as Dothistroma pini, there has been considerable taxonomic discordance regarding the name of the patho...

Dothistroma needle blight (DNB) is one of the most important diseases of pine. Although its notoriety stems from Southern Hemisphere epidemics in Pinus radiata plantations, the disease has increased in prevalence and severity in areas of the Northern Hemisphere, including Europe, during the last two decades. This increase has largely been attribute...

Dothistroma needle blight of Pinus spp. is a serious disease that can be caused by two distinct fungal species: Dothistroma septosporum and D. pini. Dothistroma septosporum has a broad pine host range, a worldwide distribution and has caused many serious epidemics. In contrast, D. pini has a more limited distribution; known only from Europe and the...

South Africa is one of the leading maize-producing countries in sub-Saharan Africa. Since the 1980s, Cercospora zeina, a causal agent of gray leaf spot (GLS) of maize, has become endemic in South Africa, and is responsible for substantial yield reductions. To assess genetic diversity and population structure of C. zeina in South Africa, 369 isolate...

Exserohilum turcicum is the causal agent of northern corn leaf blight, a destructive foliar disease of maize that results in yield losses worldwide. In South Africa, typical yield losses range from 15 to 30%. Previous studies found high haplotypic diversity with evidence for sexual recombination in E. turcicum populations from tropical climates suc...

Ceratocystis pirilliformis was first described from wounds on Eucalyptus trees in Australia and subsequently found as a common wound inhabitant on these trees in South Africa. During a recent disease survey carried out to identify Ceratocystis species infecting tree wounds in South Africa, C. pirilliformis was isolated from various tree species, in...

Geographical range expansion or host shifts are amongst the various evolutionary forces that underlie numerous emerging diseases caused by fungal pathogens. In this regard, Ceratocystis albifundus, the causal agent of a serious wilt disease of Acacia mearnsii trees in Africa, was recently identified killing cultivated Protea cynaroides in the Weste...

Lecanosticta acicola is a heterothallic ascomycete that causes brown spot needle blight on native and non-native Pinus spp. in many regions of the world. In this study we investigated the origin of European L. acicola populations and estimated the level of random mating of the pathogen in affected areas. Part of the Elongation Factor 1-α gene was s...

The genomes of Ceratocystis eucalypticola, Chrysoporthe cubensis, Chrysoporthe deuterocubensis, Davidsoniella virescens, Fusarium temperatum, Graphilbum fragrans, Penicillium nordicum and Thielaviopsis musarum are presented in this genome announcement. These seven genomes are from plant pathogens and otherwise economically important fungal species....

The aim of this study was to assess potential candidate gene regions and corresponding universal primer pairs as secondary DNA barcodes for the fungal kingdom, additional to ITS rDNA as primary barcode. Amplification efficiencies of 14 (partially) universal primer pairs targeting eight genetic markers were tested across > 1 500 species (1 931 strai...

Dothistroma needle blight (DNB), caused by Dothistroma septosporum and Dothistroma pini, is a highly damaging disease of pine. DNB was originally considered a problem on exotic Pinus radiata plantations in the Southern Hemisphere and on both exotic and native pines in parts of North America in the 1960s. Since the mid-1990s, however, DNB has increa...