Summary
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 new reports of this pathogen in Europe and in North America during the course of the past 10 years. This is despite the fact that quarantine practices and eradication protocols are in place to prevent its spread.
Taxonomy
Kingdom Fungi; Phylum Ascomycota; Subphylum Pezizomycotina; Class Dothideomycetes; Subclass Dothideomycetidae; Order Capniodales; Family Mycosphaerellaceae; Genus Lecanosticta.
Host range and distribution
Lecanosticta spp. occur on various Pinus species and are found in North America, Central America, South America (Colombia), Europe as well as Asia.
Disease symptoms
Small yellow irregular spots appear on the infected pine needles that become brown over time. They can be surrounded by a yellow halo. These characteristic brown spots develop to form narrow brown bands that result in needle death from the tips down to the point of infection. Needles are prematurely shed, leaving bare branches with tufts of new needles at the branch tips. Infection is usually most severe in the lower parts of the trees and progresses upwards into the canopies.
Useful websites
The EPPO global database providing information on L. acicola (https://gd.eppo.int/taxon/SCIRAC)
Reference genome of L. acicola available on GenBank (https://www.ncbi.nlm.nih.gov/genome/?term=Lecanosticta+acicola)
JGI Gold Genome database information sheet of L. acicola sequenced genome (https://gold.jgi.doe.gov/organism?xml:id=Go0047147)
Needle blights are serious fungal diseases affecting European natural and planted pine forests. Brown-spot needle blight (BSNB) disease, caused by the fungus Lecanosticta acicola, causes canopy ...defoliation and severe productivity losses, with consequences depending on host susceptibility. To gain new insights into BSNB plant-pathogen interactions, constitutive and pathogen-induced traits were assessed in two host species with differential disease susceptibility. Six-month-old Pinus radiata D. Don (susceptible) and Pinus pinea L. (more resistant) seedlings were needle inoculated with L. acicola under controlled conditions. Eighty days after inoculation, healthy-looking needles from symptomatic plants were assessed for physiological parameters and sampled for biochemical analysis. Disease progression, plant growth, leaf gas-exchanges and biochemical parameters were complemented with hormonal and untargeted primary metabolism analysis and integrated for a holistic analysis. Constitutive differences between pine species were observed. Pinus pinea presented higher stomatal conductance and transpiration rate and higher amino and organic acids, abscisic acid as well as putrescine content than P. radiata. Symptoms from BSNB disease were observed in 54.54% of P. radiata and 45.45% of P. pinea seedlings, being more pronounced and generalized in P. radiata. For both species, plant height, sub-stomatal CO2 concentration and water-use efficiency were impacted by infection. In P. radiata, total soluble sugars, starch and total flavonoids content increased after infection. No differences in hormone content after infection were observed. However, secondary metabolism was induced in P. pinea visible through total phenolics, flavonoids and putrescine accumulation. Overall, the observed results suggest that P. pinea constitutive and induced traits may function as two layers of a defence strategy which contributed to an increased BSNB resistance in comparison with P. radiata. This is the first integrative study linking plant physiological and molecular traits in Pinus-Lecanosticta acicola pathosystem, contributing to a better understanding of the underlying resistance mechanisms to BSNB disease in pines.
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. guatemalensis, have recently been described from Mexico and Guatemala respectively based on morphology and sequence-derived phylogenetic inference. However, the putative native pathogen, L. acicola, was not found in those areas. In this study, the species diversity of a large collection of Lecanosticta isolates from Central America was considered. Phylogenetic analyses of the BT1, ITS, MS204, RPB2 and TEF1 gene regions revealed six species of Lecanosticta, four of which represented undescribed taxa. These are described here as Lecanosticta jani sp. nov. from Guatemala and Nicaragua, L. pharomachri sp. nov. from Guatemala and Honduras, L. tecunumanii sp. nov. from Guatemala and L. variabilis sp. nov. from Guatemala, Honduras, and Mexico. New host and country records were also found for the previously described L. brevispora and L. guatemalensis. Lecanosticta acicola was not found in any of the samples from Central America, and we hypothesize that it could be a northern hemisphere taxon. The high species diversity of Lecanosticta found in Mesoamerica suggests that this is a centre of diversity for the genus.
Lecanosticta acicola is a pine needle pathogen causing brown spot needle blight that results in premature needle shedding with considerable damage described in North America, Europe, and Asia. ...Microsatellite and mating type markers were used to study the population genetics, migration history, and reproduction mode of the pathogen, based on a collection of 650 isolates from 27 countries and 26 hosts across the range of L. acicola. The presence of L. acicola in Georgia was confirmed in this study. Migration analyses indicate there have been several introduction events from North America into Europe. However, some of the source populations still appear to remain unknown. The populations in Croatia and western Asia appear to originate from genetically similar populations in North America. Intercontinental movement of the pathogen was reflected in an identical haplotype occurring on two continents, in North America (Canada) and Europe (Germany). Several shared haplotypes between European populations further suggests more local pathogen movement between countries. Moreover, migration analyses indicate that the populations in northern Europe originate from more established populations in central Europe. Overall, the highest genetic diversity was observed in south‐eastern USA. In Europe, the highest diversity was observed in France, where the presence of both known pathogen lineages was recorded. Less than half of the observed populations contained mating types in equal proportions. Although there is evidence of some sexual reproduction taking place, the pathogen spreads predominantly asexually and through anthropogenic activity.
The pine needle pathogen Lecanosticta acicola has been introduced into Europe on several separate occasions with human activity supporting the pathogen's onwards spread from already established European populations into new areas.
In 2018, L. acicola was detected for the first time on a non-pine host in an arboretum in Turkey on a Lebanon cedar (Cedrus libani) showing needle blight symptoms (Oskay et al., 2020). Since 2019 it ...has been considered a regulated non-quarantine pest in the European Union. In parallel, total DNA was extracted from symptomatic needle pieces and the presence of L. acicola was confirmed by a specific real-time PCR assay using the L. acicola-specific primer/probe combination Latef-F1/-R1/-P1 (Iooset al., 2010). Pinus spp. (including Pinus nigra subsp. laricio) are widely present in the regions concerned, brown spot needle blight has not been identified despite intensive inspection of trees in this genus close to the affected cedars.
The defoliation of the eastern white pine (Pinus strobus) across the northeastern United States is an escalating concern threatening the ecological health of northern forests and economic vitality of ...the region's lumber industry. First documented in the spring of 2010 affecting 24 328 hectares in the state of Maine, white pine needle damage (WPND) has continued to spread and is now well established in all New England states. While causal agents of WPND are known, current research is lacking in both sampling distribution and the specific environmental factor(s) that affect the development and spread of this disease complex. This study aims to construct a more detailed distribution map of the four primary causal agents within the region, as well as utilize long‐term WPND monitoring plots and data collected from land‐based weather stations to develop a climatic model to predict the severity of defoliation events in the proceeding year. Sampling results showed a greater distribution of WPND than previously reported. WPND was generally found in forest stands that compromised >50% eastern white pine by basal area. No single species, nor a specific combination of species had a dominating presence in particular states or regions, thus supporting the disease complex theory that WPND is neither caused by an individual species nor by a specific combination of species. In addition, regional weather data confirmed the trend of increasing temperature and precipitation observed in this region with the previous year's May, June, and July rainfall being the best predictor of defoliation events in the following year. Climatic models were developed to aid land managers in predicting disease severity and accordingly adjust their management decisions. Our results clearly demonstrate the role changing climate patterns have on the health of eastern white pine in the northeastern United States.
Brown spot needle blight, a disease of pine trees caused by the pathogenic fungus Lecanosticta acicola, has been known in Lithuania since 2009 and in Poland since 2014, but data on the distribution ...and population genetics of this needle pathogen were lacking. In order to investigate the genetic diversity, population structure and reproductive mode of L. acicola, 93 isolates were isolated from Pinus mugo needles in 2017–2019 and analysed using 11 microsatellite and two mating‐type markers. This study revealed 47 unique multilocus haplotypes among all investigated isolates; two genetically distinct populations of L. acicola (LIT‐E and LIT‐W) were identified in Lithuania and one population (POL‐N) in the coastal region of northern Poland. The most genetically diverse population was the LIT‐E population occurring in the eastern continental part of Lithuania, followed by the LIT‐W population spreading along the western Baltic Sea coast. All populations in both countries are characterized by low genetic diversity and contain clones, with the northern Polish population having the lowest mean genetic diversity and the greatest clonal fraction. Both mating types are present in the Lithuanian populations, demonstrating that sexual reproduction is possible, whereas only one mating type is present in the Polish population. However, the sexual stage (teleomorph) has not yet been found on infected needles, and asexual reproduction predominates. High gene flow from the eastern Lithuanian population to the northern Poland population was found, suggesting that the Polish coastal population may have been introduced from the central part of Lithuania and did not spread naturally along the Baltic Sea coast from the western Lithuanian population.
Three genetically different L. acicula populations were identified. High gene flow from the eastern Lithuanian to the northern Polish population suggested that the latter may have been introduced from the central part of Lithuania.
•Pine tree’s health monitoring through their acoustic response.•Evaluation of Lecanostica acicola fungus as a result of the drying of the tree.•Correlation between frequency drift and mass ...loss.•Comparison between expert’s visual assessment and acoustic response on real trees.•Acoustic response foresees the evolution of the illness before leaves turn brown.
Over the past years, the Lecanosticta acicola fungus or brown band is seriously damaging the pine forests of northern Spain. This fungus happens to dry the leaves and branches of trees. The present article describes the equipment and methodology for assessing the severity and spread of diseases in trees quickly, easily and cheaply. The concept is based on a basic assumption: a sick tree does not sound the same when it is hit as a healthy one does. The breakthrough character of the present work comes from a basic mechanical principle: if a tree loses water its density is reduced, so the sound that it makes when it is hit, also known as its acoustic response, is higher. If the tree is healthy it will grow, so the sound will be the same or deeper. The human ear cannot distinguish these variations or quantify them, but a microphone with an acquisition system can. After initial proofs of concept on real trunks, the function that relates the frequency increase to the degree of dehydration of the tree, and therefore to the severity of the disease, has been identified. Then, the method has been tested in a real forest with sick pines and compared to visual inspection of an expert. After several months of tests, it has been concluded that the trend of the acoustic method coincides with the visual assessment, with the difference that it is objective, while visual inspection is not. It has even demonstrated to be able to foresee the healing of trees before new leaves start to sprout.
Red band needle blight caused by Dothistroma septosporum and D. pini, and brown spot needle blight caused by Lecanosticta acicola provoke severe and premature defoliation in Pinus, and subsequent ...reduction of photosynthetic surfaces, vitality, and growth in young and adult trees. The recurrent damage results in branch and tree death. Until recently, pine needle blight diseases have had only minor impacts on native and exotic forest trees in the North of Spain, but in the past five years, these pathogen species have spread widely and caused severe defoliation and mortality in exotic and native plantations of Pinus in locations where they were not detected before. In an attempt to understand the main causes of this outbreak and to define the effectiveness of owners' management strategies, four research actions were implemented: a survey of the management activities implemented by the owners to reduce disease impact, the evaluation of specific symptoms and damage associated with infection, and the identification of the causative pathogenic species and their reproductive capacity. Morphological characteristics of the fungus and molecular identification were consistent with those of Lecanosticta acicola and Dothistroma spp., D. septosporum, D. Pini, and both mating types were present for the three identified pathogens. The local silvicultural management performed, mainly pruning and thinning, was not resulting in the expected improvement. The results of this study can be applied to establish guidelines for monitoring and controlling the spread of needle blight pathogens.
Conifers severely affected by brown needle blight disease caused by the ascomycete Lecanosticta acicola (Thüm.) Syd. show defoliation, reduced growth, and death. Although L. acicola has been known in ...Europe since 1942, its teleomorph, Mycosphaerella dearnessii Rostrup, has not yet been found. In this brief, we address the occurrence of Mycosphaerella dearnessii in dead needles cast from Pinus radiata D. Don collected in the north of Spain (Basque country). To our knowledge, this is the first report of M. dearnessii, teleomorph of L. acicola, in Europe.
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