Red Band Needle Blight Research Articles

Identification and sequence determination of a new chrysovirus infecting the phytopathogenic fungus Dothistroma septosporum

A new double-stranded (ds) RNA mycovirus has been identified in isolate Ds752-1 of the phytopathogenic fungus Dothistroma septosporum, the causal agent of Dothistroma needle blight, also known as red band needle blight or pine needle blight. Dothistroma septosporum chrysovirus 1 (DsCV-1) is a new member of the genus Alphachrysovirus in the family Chrysoviridae. The DsCV-1 genome comprises four dsRNA elements designated 1, 2, 3, and 4 from largest to smallest. dsRNA1 encodes an RNA-dependent RNA polymerase (RdRP) that is most similar to the RdRP of Erysiphe necator associated chrysovirus 3. dsRNA2 potentially encodes two hypothetical proteins, one of which is small and has no homology to known proteins, and one of which is large with significant sequence similarity to the alphachryso-P3 of other alphachrysoviruses. dsRNA3 and dsRNA4 encode a coat protein (CP) and a putative cysteine protease, respectively. This is the first report of a mycovirus infecting the fungus D. septosporum, and DsCV-1 is one of three Chrysoviridae family members found to possess genomic dsRNAs potentially encoding more than one protein.

New data on the spread of the invasive species Dothistroma septosporum (Dorogin) M. Morelet in Belarus

Red band needle blight, or Dothistroma needle blight is one of the most common and harmful diseases of pine. The causative agents of the disease are pathogenic micromycetes Dothistroma septosporum (Dorogin) M. Morelet and Dothistroma pini Hulbary. Dothistroma needle blight was firstly detected in Belarus in 2012 year, but till now information about this disease in the republic is fragmentary. The article presents the results of a survey of different pine trees, carried out in the period 2016–2020 years in botanical and dendrological gardens, forest nurseries and mini-arboretums at forestry enterprises, urban stands, nurseries of decorative plants, garden centers, for the presence of Dothistroma needle blight. The species identification of the causative agent of the disease was carried out by mycological and molecular genetic methods. In this study, Dothistroma needle blight was revealed on individual trees of Pinus mugo, P. nigra and P. ponderosa in the stands of the Central Botanical Garden of the NAS of Belarus, the dendrological garden of the Glubokoe experimental forestry enterprise, in the nurseries of decorative plants in the Grodno and Minsk regions. In the collected samples of needles, the invasive species Dothistroma septosporum was identified. The frequency of occurrence of the pathogen was 4.8–7.2 %, the proportion of observation sites in which this disease was detected at 60 %. The detection of Dothistroma needle blight on pine trees, mainly on planting material imported from abroad, indicates a transboundary route of D. septosporum entering the country. Analysis of literature data indicates the potential danger of Dothistroma needle blight for pine stands in the republic, which in turn requires the organization of regular monitoring of the disease and the development of methods to limit the spread of D. septosporum in the republic.

Combined use of spectral and structural characteristics for improved red band needle blight detection in pine plantation stands

Current trends in research for detection of infections in forests almost exclusively involve the use of a single imaging sensor. However, combining information from a range of sensors could potentially enhance the ability to diagnose and quantify the infection. This study investigated the potential of combining hyperspectral and LiDAR data for red band needle blight detection. A comparative study was performed on the spectral signatures retrieved for two plots established in lodgepole pine stands and on a range of LiDAR metrics retrieved at individual tree-level. Leaf spectroscopy of green and partially chlorotic needles affected by red band needle blight highlighted the green, red and short near-infrared parts of the electromagnetic spectrum as the most promising. A good separation was found between the two pine stands using a number of spectral indices utilising those spectral regions. Similarly, a distinction was found when intra-canopy distribution of LiDAR returns was analysed. The percentage of ground returns within canopy extents and the height-normalised 50th percentile (height normalisation was performed to each tree’s canopy extents) were identified as the most useful features among LiDAR metrics for separation of trees between the plots. Analysis based on those metrics yielded an accuracy of 80.9%, indicating a potential for using LiDAR metrics to detect disease-induced defoliation. Stepwise discriminant function analysis identified Enhanced Vegetation Index, Normalised Green Red Difference Index, percentage of ground returns, and the height-normalised 50th percentile to be the best predictors for detection of changes in the canopy resulting from red band needle blight. Using a combination of these variables led to a substantial decrease of unexplained variance within the data and an improvement in discrimination accuracy (96.7%). The results suggest combining information from different sensors can improve the ability to detect red band needle blight.

Canopy temperature from an Unmanned Aerial Vehicle as an indicator of tree stress associated with red band needle blight severity

Monoculture plantation woodlands are particularly vulnerable to disturbance events as species uniformity makes such stands highly susceptible to pests and diseases. Red band needle blight (caused by the fungus Dothistroma septosporum) is a disease which has a particularly significant economic impact on pine plantation forests worldwide, affecting diameter and height growth. However, monitoring its spread and intensity is complicated by the fact that the diseased trees are often only visible from aircraft in the advanced stages of the epidemic. Remote sensing could potentially aid in the detection of infected stands and in monitoring disease development and spread. Thermography is one of the techniques that can be used for monitoring changes in the physiological state of plants following infection. However, the use of thermography in forestry has so far been restricted by poor spatial resolution (satellite-based sensors) or high data acquirement costs (airborne sensors). This paper investigates the use of Unmanned Aerial Vehicle (UAV)-borne thermal systems for detecting disease-induced canopy temperature increase and explores the influence of the imaging time and weather conditions on the detected relationship. Furthermore, the potential of a number of airborne LiDAR-derived structural metrics for detection of changes in the canopy structure following the infection are investigated. The study was located in a diseased Scots pine (Pinus sylvestris) stand in Queen Elizabeth II Forest Park (central Scotland, UK), where 60 sample trees were surveyed. The thermal imagery was acquired at six different times of a day from an altitude of 60 m. Statistically significant correlation between canopy temperature depression (CTD) and disease levels was found for most of the flights (R2 between 0.27 and 0.41), which may be related to the needle damage symptoms caused by the disease, i.e. loss of cellular integrity, necrosis and eventual desiccation. Furthermore, the standard deviation of the crown temperature exhibited weak but statistically significant correlation (R2 between 0.11 and 0.13). The combination of CTD and standard deviation of crown temperature in a partial least squares regression (PLSR) further improved the observed relationship with the estimated disease level. Inclusion of LiDAR structural metrics was also investigated but only provided a slight improvement. A change in environmental conditions altered the magnitude of differences between canopy temperatures; no significant correlation with disease level was found in the morning flight, whilst the strongest relationship was obtained at the time of highest solar radiation, which coincides with the time of maximum photosynthetic activity.

Emerging Needle Blight Diseases in Atlantic Pinus Ecosystems of Spain

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.

UAV-BORNE THERMAL IMAGING FOR FOREST HEALTH MONITORING: DETECTION OF DISEASE-INDUCED CANOPY TEMPERATURE INCREASE

Abstract. Climate change has a major influence on forest health and growth, by indirectly affecting the distribution and abundance of forest pathogens, as well as the severity of tree diseases. Temperature rise and changes in precipitation may also allow the ranges of some species to expand, resulting in the introduction of non-native invasive species, which pose a significant risk to forests worldwide. The detection and robust monitoring of affected forest stands is therefore crucial for allowing management interventions to reduce the spread of infections. This paper investigates the use of a low-cost fixed-wing UAV-borne thermal system for monitoring disease-induced canopy temperature rise. Initially, camera calibration was performed revealing a significant overestimation (by over 1 K) of the temperature readings and a non-uniformity (exceeding 1 K) across the imagery. These effects have been minimised with a two-point calibration technique ensuring the offsets of mean image temperature readings from blackbody temperature did not exceed ± 0.23 K, whilst 95.4% of all the image pixels fell within ± 0.14 K (average) of mean temperature reading. The derived calibration parameters were applied to a test data set of UAV-borne imagery acquired over a Scots pine stand, representing a range of Red Band Needle Blight infection levels. At canopy level, the comparison of tree crown temperature recorded by a UAV-borne infrared camera suggests a small temperature increase related to disease progression (R = 0.527, p = 0.001); indicating that UAV-borne cameras might be able to detect sub-degree temperature differences induced by disease onset.

Spore Dispersal byDothistroma septosporumin Northwest British Columbia

We studied spore dispersal by Dothistroma septosporum, causal agent of a serious outbreak of red band needle blight in lodgepole pine plantations in northwest British Columbia. Spore abundance was assessed at different distances and heights from inoculum sources and microclimatic factors were recorded during two consecutive years. Conidia were observed on spore traps from June to September during periods of rainfall. It was rare to detect spores more than 2 m away from inoculum sources. The timing and number of conidia dispersed were strongly tied to the climatic variables, particularly rainfall and leaf wetness. Should the trend toward increased spring and summer precipitation in the study area continue, the results suggest that disease spread and intensification will also increase. Increasing the planting distances between lodgepole pine trees through mixed species plantations and overall reduction in use of lodgepole pine for regeneration in wet areas are the best strategies to reduce the spread of the disease and enhance future productivity of plantations in the study area.

First Record of Dothistroma pini on Pinus nigra in Switzerland.

The mitosporic ascomycetes Dothistroma septosporum s.s. (Dorog.) Morelet and D. pini Hulbary are closely related species (1) causing red band needle blight on Pinus spp. D. septosporum (teleomorph Mycosphaerella pini Rostr.) is considered as a cosmopolitan species, whereas D. pini (no teleomorph known) seems to have a more restricted distribution area. Detected in the United States on Pinus nigra for the first time, it was later found in Russia, Ukraine, Hungary, and France on different pine species (P. radiata, P. mugo, P. pallasiana) (3). In Switzerland, Dothistroma sp. (species not further determined) was recorded in 1989 for the first time and since then only damages on planted pines (mainly P. mugo and P. nigra) in urban areas were reported (R. Engesser, personal communication). In September 2012 and in April 2013, several planted mature trees and naturally regenerated young trees of P. nigra with Dothistroma needle blight were detected on a climatically mild forest site on limestone at the shore of Lake Walensee (47°07'48.0″ N, 9°13'54.4″ E, 420 m asl). In 2012, symptomatic needles were collected from the litter under one planted mature P. nigra tree and in 2013, symptomatic needles were collected from green twigs from a 2 m tall naturally regenerated P. nigra specimen. Conidiomata were frequently observed in the red bands but no conidia were detected. For fungal isolation, the surface of infected needles was shortly disinfected with 95% ethanol. The epi- and hypo-dermis covering the still closed conidiomata was removed and small tissue samples from the mesophyll (less than 0.5 mm length) were placed on malt extract agar (15 g/liter agar, 20 g/liter malt extract) amended by 50 mg/liter oxytetracycline. Conidia were observed after one year at 4°C in the resulting pure colonies (3 to 4 cm diameter on malt extract agar medium). The conidia formed by strain OH_120923_2_1_1 (KJ878557 = D. pini) were hyaline, smooth, thin-walled, 2- to 4-celled, and 31.6 (22 to 37) × 2.8 (2 to 3.5) μm. While conidial morphology of both Dothistroma species overlap, DNA was extracted and the internal transcribed spacer (ITS) region (primers ITS 1 and ITS 4) sequenced (KJ878557 to 81). From the 25 obtained ITS sequences, seven were identical with AY808275 (D. septosporum from P. radiata, South Africa, CMW 684), three were identical with AY808302 (D. pini from P. nigra, Michigan, CMW 10951), and 15 were identical with DQ926964 (D. pini from P. pallasiana, Ukraine, CMW 23767). The North American and Ukrainian D. pini sequences (AY808302 and DQ926964) showed only 1 bp difference. In addition, mating type genes were amplified using the method described by Groenewald et al. (2) for D. pini and scored using gel electrophoresis. Analyses showed that both D. pini ITS-sequence variants (e.g., KJ878557 and KJ878558) and both mating types were sometimes present in the same needle. In two cases, both mating types and ITS-sequence variants were also present within the same lesion. Interestingly, D. pini and D. septosporum were found on the same tree but not on the same needles. This is the first report of D. pini in Switzerland. Although symptoms of red band needle blight (species not determined) were repeatedly observed on this site during the last 20 years, the disease level always remained low and no tree mortality was noted. However, due to the presence of two ITS-sequence variants and both mating types, the incidence of D. pini in Switzerland deserves attention.

Four New Host and Three New State Records of Dothistroma Needle Blight Caused by Dothistroma pini in the United States.

During 2010 and 2011, Dothistroma needle blight (DNB), also known as red band needle blight, was observed for the first time in Cass and Pembina counties in North Dakota (ND). In Pembina Co., DNB was observed in two sites in the Jay V. Wessels Wildlife Management Area (JWWMA). In September 2009, yellow spots on green needles were observed on some trees along the western edge of one planting. By June 2010, DNB was found on third- and fourth-year needles in both JWWMA plantings. Symptoms had developed into dark brown bands or spots on necrotic needles that contained erumpent black acervuli. In June 2011, similar DNB symptoms were observed on Pinus nigra, P. flexilis, P. ponderosa, P. cembra, and P. albicaulis in the Dale E. Herman Research Arboretum, Cass Co., ND. DNB was collected in July 2011 in Brookings Co., South Dakota (SD), from a seed source provenance planting of P. ponderosa. To identify the species causing the infections, symptomatic needles were collected in 2010 from both sites in JWWMA and then again from all four locations in 2011 on all pine species infected. Needles of P. nigra from a private residence near Fairland in Shelby County, Indiana (IN), were also included in the sample set. The rDNA-ITS was PCR-amplified either directly from conidia obtained from acervuli on the needles or from cultures obtained from isolations. Amplicons were sequenced and a BLAST search was performed in GenBank. The sequences of samples obtained from P. nigra, P. flexilis, P. cembra, and P. albicaulis in ND, P. ponderosa in SD, and P. nigra from IN showed 100% sequence homology with Dothistroma pini (Accession No. AY808302). These isolates were identical to all previously assayed isolates of D. pini from Nebraska, Minnesota, and Michigan in the United States. The P. ponderosa isolates from all three sites in ND differed from the other isolates and contained a 1-bp point mutation from a C to a T at site 72 (sequence deposited in GenBank, accession KJ933441). Mating type was determined using species-specific mating type primers for D. pini (3). All 26 samples from ND and SD were of the MAT-1 idiomorph, while the sample from IN contained the MAT-2 idiomorph. All cultures are maintained at FABI, University of Pretoria, South Africa. The two species that cause DNB, D. septosporum (G. Dorog.) M. Morelet and D. pini Hulbary, are morphologically indistinguishable and molecular characterization remains essential for correct species identification (1). Host and geographical distribution range determinations of Dothistroma spp. made without molecular methods are not valid. To date, species confirmed using DNA sequences in the United States include D. septosporum in the Pacific Northwest states of Oregon and Idaho on P. ponderosa, in Montana on P. contorta v. latifolia, and D. pini in the North Central states of Nebraska, Minnesota, and Michigan on P. nigra (1). This study documents the presence of D. pini in three additional states, including a first report of DNB in ND and SD. It also includes new records of D. pini infecting P. flexilis, P. cembra, P. albicaulis, and P. ponderosa. Results of this study have expanded the documented host range of D. pini in the United States from one (P. nigra) to five species. Globally, D. pini is now known to infect a total of 10 pine hosts (2,4,5).

First Report of Dothistroma pini, a Recent Agent of the Dothistroma Needle Blight, on Pinus radiata in France.

Dothistroma needle blight (DNB), also known as red band needle blight, is an important fungal disease of Pinus spp. that occurs worldwide. On the basis of molecular and morphological studies of the anamorphic stage, Barnes et al. (1) showed that two closely related species were involved in DNB: Dothistroma septosporum (Dorog.) Morelet and D. pini Hulbary. D. septosporum (teleomorph: Mycosphaerella pini Rostr.) has a worldwide distribution and is reported as the species that caused past epidemics of DNB. This species is reported on more than 80 different pine species, and Pinus radiata D. Don (Monterey pine) is classified as a highly or moderately susceptible species, depending on the published sources (4). D. pini (telemorph: unknown) was initially found on needles of P. nigra J. F. Arnold collected from 1964 to 2001 in the north central United States (Minnesota, Nebraska, and Michigan). It was subsequently found in Ukraine and southwestern Russia, where it has been associated with the emergence of DNB on P. nigra subsp. pallasiana (Lamb.) Holmboe, in Hungary on P. nigra, and in Russia on P. mugo Turra (1). In France, D. pini was reported for the first time on P. nigra, and was sometimes found in association with D. septosporum on the same needles (3). Later on, a more intensive survey of DNB was launched in France and 216 stands of Pinus sp. were studied. D. septosporum and D. pini were detected in 133 and 123 stands, respectively. Both species co-occurred in 40 stands but D. pini was only found on P. nigra (subsp. laricio and austriaca) (2). Up to now, D. pini was therefore only reported on European pine species, mainly on the different allopatric subspecies belonging to the black pine complex and on one occasion on P. mugo, which belongs to the same section and subsection as P. nigra. In March 2011, typical symptoms of DNB (needles with orangey-red brown distal ends, dark red bands, and green bases; small and black fruit bodies within the bands) were observed in a 50- to 60-year old P. radiata stand of ~3 ha located in Pyrénées Atlantiques close to the Spanish border (1°36'08″ W, 43°19'51″ N). The density of pine was relatively low and patches of natural regeneration were present. Although nearly all of the trees showed DNB symptoms, less than 50% of their needles were affected by the disease. In this stand, needles showing typical DNB symptoms were randomly taken from four pines and mixed together to form a single sample for analysis. Total DNA was extracted from symptomatic needle pieces. The presence of D. pini was confirmed by a specific multiplex real-time PCR analysis using the D. pini-specific primers/probe combination DPtef-F1-/R1/-P1 (3), and by sequencing a D. pini-specific amplicon generated by another conventional PCR (3) using DPtef-F/DPtef-R primers (GenBank Accession KC853059) (3). D. septosporum was not detected in the sample. To our knowledge, this is the first report worldwide of D. pini on P. radiata, a pine species largely planted in Spain and in the Southern Hemisphere. This is also the first report of this pathogen on a non-European pine species. The original native range and the host range of D. pini remain unknown and there is currently no data about host preferences or aggressiveness on different pine species.

Incorporating climate change into pest risk models for forest pathogens: a role for cold stress in an era of global warming?

Climate change may alter the distribution and activity of native and alien pathogens that infect trees and, in severe cases, cause tree death. In this study, potential future changes in climate suitability are investigated for three forest pathogens that occur in western North America: the native Arceuthobium tsugense subsp tsugense, hemlock dwarf mistletoe, and two alien invasive species, Dothistroma septosporum, the cause of red band needle blight or Dothistroma needle blight, and Phytophthora ramorum, the cause of sudden oak death or ramorum blight. Specifically, the software CLIMEX is used to calculate Cold-Stress, Heat-Stress, and Dry-Stress indices for each pathogen in 98,224 grid cells in North America. Downscaled climate projections from the general circulation models CGCM1, CSIROMk2, and HadCM3 drive forecasts for 2020, 2050 and 2080. These climate projections are then analyzed to forecast shifts in the geographic extent of abiotic stresses that are severe enough to directly kill pathogen propagules and prevent year-round establishment of these pathogens. Cold stress currently has a major impact on climate suitability for all three pathogens; heat stress is likely to become more significant in the future. I forecast that the geographic extent of cold stress will decline from its current levels by a constant 5% (± 1%) of all grid cells in each 30-yr projection horizon for all three pathogens. Forecasts suggest the extent of heat stress will increase concurrently by 4% (± 1%) in each 30-yr projection horizon. Drought stress shows no consistent trend over time. No disproportionate effect of climate change on the two alien invasive pathogens over the native is forecasted. These results suggest that forecasts of future climate suitability for pathogens based on historical climate normals are accurate for less than 30 yrs. Adaptive management strategies in forestry will be needed to respond as these changes unfold.

Microspatial genetic diversity of Dothistroma septosporum

SummaryThe distribution of genetic diversity in a local population of Dothistroma septosporum was determined on a microspatial geographical scale. The study was conducted in a seed orchard of Pinus nigra divided into four plots, each of 0.84 ha in area. Ninety‐two isolates were obtained from needles with red band needle blight symptoms. Molecular variance, Mantel test and autocorrelation spatial analyses were performed with the use of random amplified microsatellites markers to test the null hypothesis of a random distribution of genotypes. The groups of isolates from individual plots demonstrated small differences as regards intrapopulation variation. The mean contribution of polymorphic loci for isolate groups was almost 77%, genetic diversity 0.270, while the Shannon coefficient was 0.389. The Mantel test demonstrated a significant, positive correlation between Huff's genetic distance and geographical distance. Significant spatial genetic structure was detected with autocorrelation coefficients being significant in the first two distance classes up to about 8–12 m.

Integrating red squirrel (Sciurus vulgaris) habitat requirements with the management of pathogenic tree disease in commercial forests in the UK

The native red squirrel is being replaced by the introduced North American eastern grey squirrel in the UK. Here, Sitka spruce dominated plantations containing a larch and pine element offer the best long-term opportunity to conserve the red squirrel because they can sustain populations in a forest environment where the competitive advantage of the grey squirrel is reduced. Forest habitat management in designated stronghold areas in England and Scotland is therefore a key strategy for red squirrel conservation. However, the threat of pathogenic tree disease is already leading to changes in forest composition through modified thinning and planting regimes. This has the potential of not only altering habitat suitability for red squirrels but also the competitive ability of grey squirrels. For example, Phytophthora ramorum can severely affect Japanese larch, whilst other common crop species such as Corsican pine, Scots pine and lodgepole pine are all vulnerable to Red Band Needle Blight (Dothistroma septosporum); factors driving significant changes in future forest composition. In this paper we wish to highlight the serious impact of these diseases on established red squirrel management options. We examine proactive and reactive management in three case studies which are attempting to integrate red squirrel habitat requirements into evolving tree disease management protocols. We recommend specific tree species that are both less susceptible to infections and offer potential alternative seed sources for red squirrels, whilst stressing the need for research into grey squirrel exploitation of such crops. We also highlight how the presence of grey squirrels is limiting the use of hazel and other broadleaved species in this context. Finally, a flexible red squirrel management protocol is presented to assist forest managers to integrate red squirrel conservation with the threat posed by Red Band Needle Blight and P. ramorum.

First Report of Mycosphaerella pini Causing Red Band Needle Blight on Scots Pine in Norway.

During a survey conducted in August 2009 in northern Norway, symptoms typical for red band needle blight (1) were observed in four young Scots pine (Pinus sylvestris) stands. The stands, less than 15 years old, were located in humid sites near rivers in Bardu and Målselv municipalities, Troms County. Many of the oldest needles (2- to 3-yearsold) in the lower part of young trees were partially or completely brown, but still attached, and red bands could be observed. Aggregations of conidial stromata were often seen in the red bands. Conidia were hyaline, smooth, thin walled, and filiform, 1.9 to 2.6 μm wide and 12 to 36 μm long. Isolations were made from conidiomata and the identity of Mycosphaerella pini was confirmed by partial sequencing of the internal transcribed spacer (ITS) region of a sample from Målselv (69°00'N, 18°51'E) (GenBank Accession No. JF796109). In June 2010, a survey was done in southeastern Norway where nearly 100 stands with young Scots pine, up to 20 years old, were inspected and typical symptoms of red band needle blight were observed in 10 stands in three municipalities in Hedmark County (Eidskog, Kongsvinger, and Trysil), less than 25 km from the Swedish border, and in one stand in Buskerud County (Nedre Eiker). Lower branches of up to 5 m tall trees had symptoms of red band needle blight, mainly on the oldest needles. In the red bands, acervuli of Dothistroma septosporum, the anamorph of M. pini, appeared. Typical conidia from acervuli were germinated in water agar and resulting mycelium was transferred to modified orange serum agar. Two isolates were sequenced as above and both herbarium samples and isolates (Kongsvinger, 60°06'N, 12°04'E; GenBank Accession No. JF796108 and Trysil, 61°14'N, 12°22'E; GenBank Accession No. JF796107) were deposited at the Norwegian Forest and Landscape Institute. To fulfill Koch's postulates, symptoms were reproduced by artificial inoculation onto 1-year-old Scots pine seedlings. In June 2010, a pooled conidial suspension (2.4 to 3.8 × 103 conidia per ml) from two single-conidium cultures was sprayed to runoff onto 128 seedlings and 64 seedlings were mock sprayed with distilled water. First symptoms (brown segments and red bands) appeared on inoculated seedlings 1 month later and acervuli appeared after another 6 to 8 weeks. M. pini was reisolated from the acervuli. Three months after inoculation, 90% of inoculated seedlings showed symptoms while all uninoculated seedlings were healthy. Damage caused by M. pini has increased in the northern hemisphere during the last 15 to 20 years, possibly because of climate change (4). In 2006, the fungus was recorded in Estonia (2), in 2008 in Finland (3), and by 2009, the disease had spread over large areas in Finland including the region near the Norwegian border in the north. The disease has been in Sweden for a few years (J. Stenlid, personnel communication). In southern Norway, the disease has mainly been observed near the Swedish border so here the disease may originate from Sweden. So far, however, only small areas of Norway have been surveyed. Both natural spread and human transport dissemination may be occurring.

Nested polymerase chain reaction–based detection of Dothistroma septosporum, red band needle blight of pine, a tool in support of phytosanitary regimes

Red band needle blight is one of the most important foliar diseases of Pinus species and is of increasing international forest health and biosecurity concern. To provide a rapid identification technique for this pathogen in support of official control measures, a nested polymerase chain reaction-based diagnostic assay that employs species-specific primer sets has been developed. The assay is able to detect the presence of the pathogen direct from pine needles, irrespective of host species, to within 10 fg of target DNA, the equivalent of approximately 2-3 ascospores or hyphael cells.

Records of Brown spot needle blight related to Lecanosticta acicola in the Czech Republic

There are two records of brown spot needle blight caused by <I>L. acicola</I> in the Czech Republic up to date. Disease was first reported on June 2007 in National Nature Reserve (NNR) Červená Blata, South Bohemia. A more recent discovery of <I>L. acicola</I> took place on August 2008 in the NNR Borkovická Blata. The disease was observed on 10-60 year old <I>Pinus rotundata</I>. Both locations with infected trees are situated inside nature conservation sites under strict protection regimes that are located approximately 50 km apart. In both sites, <I>L. acicola</I> occurred simultaneously with <I>Dothistroma septospora</I>, the red band needle blight causal agent on Scots pine (<I>Pinus sylvestris</I>), bog pine (<I>P. rotundata</I>) and their hybrid (<I>P. × digenea</I>). However, infections of both diseases on the same tree have not yet been observed.

British Columbia's Northern Interior Forests Dothistroma Stand Establishment Decision Aid

Dothistroma needle blight, also known as red band needle blight, is caused by the fungus Dothistroma septosporum. It affects over 60 species of pine in 45 countries and is considered the most destructive pine needle disease in the world. All pine species native to British Columbia are susceptible and the fungus is widely distributed wherever host species can be found. Infection is caused by rain splash and air dispersal of the spores. In the southern hemisphere, it has been a major problem for decades. In British Columbia, however, damage levels from this pathogen have historically been low. Recent widespread defoliation, mortality (including mature tree mortality), and plantation failure caused by Dothistroma in the northwest portion of the province may be a result of changing climatic conditions that allow the fungus to develop in a way that was not previously possible.The Stand Establishment Decision Aid (SEDA) format has been used to extend information on a variety of vegetation and forest health concerns in British Columbia. The two-page SEDA presented in this extension note was developed to summarize information that provincial forest managers will need to mitigate the impacts of Dothistroma needle blight. The first page provides information on susceptible stand types, disease biology, hazard ratings, and appropriate management practices. The second page outlines forest productivity considerations and risks to human health. A resource and reference list that readers can use to find more detailed information is also included. Most reference material that is not available online can be ordered through libraries or the Queen's Printer at: www.qp.gov.bc.ca

First Observations of Mycosphaerella pini on Scots Pine in Finland.

Red band needle blight of pines caused by Mycosphaerella pini (anamorph Dothistroma septosporum) has recently been recorded on Scots pine (Pinus sylvestris) at 14 rural districts in southern and central Finland. Scots pine is the most common and commercially most important tree species in Finland. Red bands with aggregations of conidial stromata on otherwise brown attached needles were frequently encountered on saplings and young trees in dense stands and sporadically on lower twigs of mature trees within 2 m of the ground. These symptoms and signs, typical for M. pini (1), were also observed on needles of P. contorta and P. cembra, which occur in Finland in low frequency. Symptoms of red band needle blight and abundant conidial stromata were found in March and April of 2008 after a mild and rainy winter. After this time, the frequency at which fresh acervuli were observed decreased. Conidia were isolated after squeezing conidial stromata into a drop of sterile water and rinsing out the drop onto water agar from where single conidia were picked up from under the microscope with a modified Pasteur pipette. The conidia were hyaline, smooth, thin walled, filiform, 2.0 to 2.7 (2.4) μm wide, and 15 to 37 (29.4) μm long. Germination of the conidia on water agar was 100%. The cultures grew slowly and reached a diameter of 4 to 10 mm within 3 weeks on modified orange serum agar (2) at 20°C and abundantly produced conidia. Complete sequences of the internal transcribed spacer (ITS) region including the 5.8S rRNA gene were obtained for three isolates from different rural districts: Hartola (61°34'N, 26°01'E), Kangasniemi (61°59'N, 26°39'E), and Suonenjoki (62°37'N, 27°07'E). These sequences are deposited in GenBank with Accession Nos. EU834294, EU834295, and EU834296 and are identical to each other and to more than 50 M. pini sequences in GenBank, including those of several Estonian and Austrian isolates. These isolates are deposited in the culture collection of the Finnish Forest Research Institute with identifiers Dot1, Dot2, and Dot8. Symptoms were reproduced after inoculation of 1-year-old Scots pine seedlings growing in seedling trays with 115 cm3 cavities. A conidial suspension (5 to 6·× 103 conidia ml-1) was prepared from two single-conidial cultures (Dot10 and Dot15), combined, and sprayed during July 2008 onto 192 seedlings until needles looked completely wet. Sixty-four seedlings were sprayed with distilled water as a control treatment. Seedlings were incubated outdoors in Suonenjoki and covered with a transparent plastic hood for the first 5 days after inoculation. The first symptoms (brown segments and red bands on needles) appeared on inoculated seedlings 1 month later, and conidial stromata appeared after another 2 to 4 weeks. M. pini was reisolated from the acervuli of 10 sample needles. Three months after inoculation, all inoculated seedlings showed symptoms while all noninoculated seedlings were healthy. It is possible that M. pini has spread recently from the south since it was identified for the first time in Estonia 2 years earlier (3). Although the Gulf of Finland separates Finnish pine forests from Estonian pine forests by approximately 50 to 100 km, spores may have been aerially disseminated over this distance. Alternatively, introduction of M. pini to Finland may have occurred on imported seedlings.

Introduced pathogens found on ornamentals, strawberry and trees in Finland over the past 20 years

The comparative ease and speed of international trade and travel have enabled or enhanced the spread of pests around the globe. For example, trade in ornamental plants has bolstered the spread of alien Oomycetes such as pathogenic species of Phytophthora. To date, four Phytophthora species have been identified in Finland: P. cactorum on Fragaria x ananassa, Betula pendula and Rhododendron spp., P. plurivora on Rhododendron spp. and Syringa vulgaris, and P. pini and P. ramorum on Rhododendron spp. The ascomycete Colletotrichum acutatum, which was listed as a quarantine pathogen by the European Union until 2009, was introduced in 2000 and can survive in plant debris over two winters in Finland. Positive PCR results have also been obtained from bait plants grown in soil collected from locations where diseased Fragaria x ananassa plants had earlier been destroyed. In the mid-1990s, there was an epidemic of foliar rust caused by the Asian basidiomycete Melampsoridium hiratsukanum on Alnus glutinosa and A. incana. Recently, two ascomycetes that have been introduced are Dothistroma septosporum (responsible for red band needle blight on Pinus sylvestris) and Chalara fraxinea (causing ash decline on Fraxinus excelsior).;

Mycosphaerella dearnessii and Mycosphaerella pini

<i>Mycosphaerella dearnessii</i> and <i>Mycosphaerella pini</i>