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1.
To clarify the infection approach of Diplodia sapinea, a pathogen that causes tip blight of Pinus tabulaeformis, the infection process of the pathogen in needles was observed using scanning electron microscopy (SEM). In addition, the disease incidence on branches damaged by Aphrophora flavipes (Hemiptera: Cercopidae) and Dioryctria splendidella (Lepidoptera: Pyralidae) in the forest was also investigated. Then, branches and needles of P. tabulaeformis were inoculated using the D. sapinea spore suspension under indoor and field conditions. The results showed that the damage caused by A. flavipes could aggravate the occurrence of tip blight of P. tabulaeformis to some extent. Moreover, the pathogen could also penetrate 1‐, 2‐ and 3‐year‐old pine needles through stomata in the field. The pathogen infected the 1‐year‐old branches first and then gradually spread to 2‐ and 3‐year‐old branches. 相似文献
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Ana Cristina Silva Joana Henriques Eugnio Diogo Ana Paula Ramos Helena Bragana 《Forest Pathology》2020,50(1)
The fungus Sydowia polyspora is frequently isolated from conifers worldwide and is considered a pathogen on several hosts. Stone pine (Pinus pinea) is one of the most important forestry species throughout the Mediterranean basin due to the value of the edible pine nut. Stone pines showing tip dieback, needles with tan‐ to yellow‐coloured lesions and shoot death, observed in stands in Portugal, were sampled for analysis. Fungal colonies covered with cream‐coloured spore masses, were consistently obtained. Morphological and phylogenetic analyses of the ITS rDNA region enabled identification of these isolates as S. polyspora. Inoculation tests showed that the fungus caused lesions on excised P. pinea shoots. The symptoms observed might have a negative effect on pine nut production, and thus, evaluation of the impact of this disease is of relevance to future research. This paper is the first to report S. polyspora causing disease on P. pinea. 相似文献
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Severe dieback symptoms were observed in a 490‐ha moist ash (Fraxinus angustifolia) lowland forest stand, comprising trees over 100 years old and in 100 ha of newly planted F. angustifolia near Sinop, in Turkey. Five of the 10 soil samples collected around stem bases of the diseased trees were baited using ash leaves and yielded a Phytophthora sp. This heterothallic species produced non‐caducous, non‐papillate sporangia in non‐sterile soil extract, and fluffy, even growth on corn meal and potato dextrose agars, and suppressed, even growth on grated carrot agar. Isolates were identified as Phytophthora taxon salixsoil based on internal transcribed spacer DNA sequences. This species has been recently redesignated as P. lacustris. Three isolates were found to be pathogenic when inoculated on the stem bases of three‐year‐old F. angustifolia saplings. 相似文献
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Visualizing the early infection of Agathis australis by Phytophthora agathidicida,using microscopy and fluorescent in situ hybridization 
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下载免费PDF全文 S. E. Bellgard M. Padamsee C. M. Probst T. Lebel S. E. Williams 《Forest Pathology》2016,46(6):622-631
Phytophthora agathidicida (PTA) causes a root rot and collar rot of New Zealand kauri (Agathis australis). This study developed techniques to visualize early infection of kauri by PTA in deliberately inoculated seedlings. Conventional light microscopy was carried out on cleared and stained roots using trypan blue to observe PTA structures. Additionally, scanning electron microscopy (SEM) was used to study the PTA root structures at a higher resolution. A fluorescent in situ hybridization assay (FISH) was developed using a PTA‐specific probe to label PTA structures in planta. Infection progression in roots of 2‐year‐old kauri inoculated with PTA at 5, 10, 16 and 20 days post‐inoculation (d.p.i.) was compared using these three approaches. Light microscopy identified no Phytophthora‐like structures in the control treatments. In PTA‐inoculated plants, lignitubers were produced 5 d.p.i. in cortical cells. Infection was localized after 5 days, but as the infection progressed (up to 20 d.p.i.), the ‘degree’ of root infection increased, as did the number of replicates in which structures were observed. SEM provided higher resolution images; again, no PTA structures were observed in the negative control material examined. The slide‐based FISH‐specificity assay successfully hybridized with PTA hyphae. Fluorescence was observed using 330–380 nm excitation and an emission filter at 420 nm (DAPI), with PTA nuclei fluorescing a bright greenish‐yellow. Cross‐reactivity was not observed when the assay was applied to six other non‐target Phytophthora species. Successful hybridization reactions occurred between the primer and PTA structures in planta. Applying this FISH assay has allowed clear differentiation of the intracellular and intercellular structures of PTA. The technique can be applied to longer term studies or analysis of ex situ inoculation studies aiming to elucidate differential host‐responses to the pathogen. Additionally, the technique could be applied to study the interactions with other fungal endophytes (e.g. mycorrhizal fungi), which could be assessed for biocontrol potential as part of the integrated management of the disease. 相似文献
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The aim of this study was to assess genetic diversity and spatial distribution of 123 strains of the root‐rot pathogen Neonectria macrodidyma isolated from fine living roots of bare‐root nursery cultivated Pinus sylvestris. We found that ITS rDNA sequences were 100% identical for all strains. Arbitrary primed PCR fragment analysis showed the presence of two distinct N. macrodidyma types (Type 1 and Type 2), which included respectively 11 and 14 genotypes composed of 1–29 strains. Results of this study indicate that N. macrodidyma is commonly associated with fine living roots of pine seedlings, is largely disseminated by asexual means of local genotypes and has even distribution in the forest nursery soils. In living roots, N. macrodidyma is likely present as dormant propagules but under favourable conditions, it may develop rapidly and have a significant negative effect on plant health and productivity. 相似文献
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Fungal abundance and diversity were assessed in two differently managed forest soils. In soil 1, chipped woody debris had been spread on the top soil and mixed with the soil by standard deep ploughing to 50 cm. In soil 2, woody debris was removed and there was no ground preparation. Ten years later, the different methods of management resulted in unexpectedly distinctive habitat heterogeneity with a high variation in structure of the mycobiota communities. Incorporation of woody debris into soil resulted in lower abundance of fungi but greater fungal diversity (which may enhance ecosystem stability) and was beneficial for the growth of Scots pines. Removal of post‐harvest woody debris from the surface of the clear‐cut site with no subsequent ground preparation, compared with incorporating chipped debris and deep ploughing, resulted in the soil of the subsequent 10‐year‐old Scots pine plantation having: (a) 159‐fold greater abundance of fungi, (b) lower fungal diversity, (c) different fungal community composition, (d) higher proportion of mycorrhizal fungi, (e) no root rot pathogens, (f) less tree biomass. The study showed that removal of post‐harvest woody debris and no ground preparation is potentially beneficial for the health of young coniferous trees. 相似文献
7.
J. F. Webber A. M. Vettraino T. T. Chang S.E. Bellgard C. M. Brasier A. Vannini 《Forest Pathology》2012,42(2):136-143
Following the discovery in 2008 of Phytophthora lateralis in forest soil under old‐growth yellow cedar (Chamaecyparis obtusa var. formosana) in north‐east Taiwan, further sampling was undertaken in the same region. Soil, root and symptomatic foliage samples were collected from five separate sites where C. obtusa was the dominant species in cloud forests at ca. 1800–2500 m. Soil and fine root samples were baited with cedar needles; both direct isolation and cedar needle baiting were used on foliage samples. Phytophthora lateralis was obtained from soil at three of the sites, but only from three of the 27 soil samples overall. Only one of 25 root samples yielded the pathogen, and this was associated with infested soil. Three foliage samples with symptoms visible as dark brown to black frond tips also yielded P. lateralis; these came from two different sites. This is the first record of P. lateralis infecting the foliage of C. obtusa. Moreover, when some of the symptomatic Chamaecyparis foliage segments were incubated, sporangia of P. lateralis formed on the necrotic tissues, sometimes in the axils of needle segments. The study provides evidence that P. lateralis has both a soil/root infecting phase and an aerial or foliar infecting phase in Taiwan, which is consistent with its unusual combination of water‐dispersed (non‐papillate) and aerially dispersed (caducous) sporangia. It also demonstrates the importance of investigating the biology, aetiology and ecological behaviour of Phytophthoras in their native, endemic environments. 相似文献
8.
During the monitoring of the mycological complex on different forest tree species in the Biogradska Gora National Park in north‐east Montenegro, symptoms indicative of ash dieback caused by Hymenoscyphus fraxineus were observed on young Fraxinus excelsior trees in the protected virgin forest, including dieback of plants and branches, wilting of leaves and shoots leading to a “flag‐like” habitus, premature shedding of leaves and longitudinal bark necroses. Using standard isolation methods, slow‐growing cultures with numerous phialides, typical of the asexual phase of the ash dieback fungus, were obtained. In addition, petioles with numerous characteristic apothecia were also recorded. This is the first report of H. fraxineus on common ash in Montenegro. Possible pathways of introduction and implications of the findings are discussed. 相似文献
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Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
10.
Genetic diversity of pine‐parasitic nematodes Bursaphelenchus xylophilus and Bursaphelenchus mucronatus in China 下载免费PDF全文
下载免费PDF全文 The internal transcribed spacer (ITS) regions of rDNA have been routinely employed for identification and phylogenetic analysis of many nematode species. In this study, the intra‐ and interspecies ITS genetic diversity of Bursaphelenchus xylophilus and Bursaphelenchus mucronatus was evaluated. Ninety‐one isolates of the two nematode species collected from 14 Chinese provinces, Japan and Korea were used for ITS‐PCR and sequencing. An unweighted pair group cluster analysis dendrogram clustered them as two B. mucronatus and one B. xylophilus independent clades. Principal component analysis showed the phylogenetic relationship of the two nematode species more clearly; B. mucronatus isolates were separated into more than four groups, whereas B. xylophilus isolates still clustered into a group. The results of the Mantel test indicated the correlation of genetic distance matrices and geographic distance matrices was significant for both nematode species. The genetic differentiation coefficient (Gst) and gene flow (Nm) of B. mucronatus were 0.341 and 1.091, respectively, suggesting the importance of landscape heterogeneity and considerable obstacles for genetic exchange among B. mucronatus isolates in China. However, Gst and Nm of B. xylophilus were 0.188 and 2.151, respectively, very different compared to B. mucronatus. This could be owing to the short‐term introduction of B. xylophilus into China and a rapid spread through anthropogenic pathways. Our work adds to the understanding of the genetic diversity and genetic relationship of the two pine‐parasitic nematode species, and will aid in controlling them in the future. 相似文献
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Giada d'Errico Elena Fanelli Alberto Troccoli Francesco Binazzi Silvia Landi Pio Roversi Francesca De Luca 《Forest Pathology》2020,50(4)
In February 2015, an unexpected windstorm downed five hectares of a European black pine Pinus nigra subsp. laricio forest formation located close to Vallombrosa, Florence (Central Italy). In the following spring, an extensive survey was conducted in the area. Felled trees, stumps and all the suitable plant material were screened for the presence of the pinewood nematode (PWN), Bursaphelenchus xylophilus, by sampling wood and bark. Bark beetles were then collected from the gallery systems on the inner side of bark samples and observed in the laboratory. The following bark beetles were morphologically identified: Ips sexdentatus, Orthotomicus erosus, O. laricis and Pityogenes bidentatusa. The dissection of Ips sexdentatus allowed the extraction of numerous nematodes that were morphologically and molecularly identified as Ektaphelenchoides pini. Conversely, only few nematode specimens were isolated from either pine bark or wood. These individuals could be only molecularly identified and belonged to an undescribed nematode taxon. Even though no PWN was recorded in the investigated sites, our survey allowed the detection of a new association between E. pini and I. sexdentatus on P. nigra. 相似文献
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In addition to Hymenoscyphus fraxineus, two fungi identified as Diaporthe eres aff. and Fusarium sambucinum aff. were also isolated from necrotic bark lesions on declining one‐year‐old Fraxinus excelsior in a forest stand in Montenegro. To examine their involvement in ash decline, a pathogenicity test was performed using under bark inoculations on one‐year‐old Fraxinus excelsior. Hymenoscyphus fraxineus was included as comparison. All three fungal species proved highly pathogenic towards one‐year‐old seedlings although lesion sizes differed significantly between the different species. Hymenoscyphus fraxineus was most aggressive, followed by F. sambucinum aff., while D. eres aff. caused the smallest lesions. This study demonstrates for the first time the ability of isolates in the D. eres and F. sambucinum species complexes to cause decline on one‐year‐old common ash seedlings. 相似文献
16.
Sabyasachi Banerjee Seema Singh Shailesh Pandey Maneesh S. Bhandari Amit Pandey Krishna Giri 《Forest Pathology》2020,50(2)
Wilt disease caused by Fusarium solani is a serious constraint to Dalbergia sissoo (shisham) plantations in northern India. In this study, the antagonistic potential of 40 bacterial isolates recovered from rhizophere soil of healthy shisham trees, and a well‐characterized Trichoderma species (Trichoderma virens) were tested for their possibility as biocontrol agents for F. solani. Two promising isolates (S1 and S15) were identified which inhibited pathogen growth, caused chitin degradation, produced siderophores and solubilized phosphate in vitro. Isolate S15 scored highest for hydrogen cyanide (HCN) production while isolate S1 was a non‐HCN producer. These two isolates were identified as Serratia marcescens (S1) and Pseudomonas azotoformans (S15) following sequence analysis of 16S rDNA. In dual culture assays, T. virens caused 80% inhibition of mycelial growth of the test fungus. The three selected antagonists when tested in planta in the glasshouse completely suppressed production of wilt symptoms on 12‐month‐old shisham plants. Further work is needed to ascertain the potential of these isolates to be used as biocontrol agents to manage shisham wilt under field conditions. 相似文献
17.
Conifer species influence Heterobasidion irregulare sporulation on stem discs exposed to natural inoculum and root wood decay in soil‐block tests 下载免费PDF全文
下载免费PDF全文 The fungal pathogen Heterobasidion irregulare has caused substantial damage to pine species in much of the south‐eastern United States, but the potential for damage from Heterobasidion root disease to forest tree species of the Great Lakes Region has not been thoroughly investigated. In each of three trials in two infested stands, fresh stem discs of six native conifer species were exposed to natural inoculum and examined for the asexual Spiniger stage of H. irregulare after incubation in the laboratory. In the first trial, the fungus was infrequently observed on discs, and differences among species were not found. But in the other two trials, detection of the pathogen was much more frequent on discs of tamarack (Larix laricina), red pine (Pinus resinosa) and white spruce (Picea glauca) than those of northern white cedar (Thuja occidentalis), eastern hemlock (Tsuga canadensis) and balsam fir (Abies balsamea). In a second study, the ability of an isolate of H. irregulare to decay root sapwood of these same species was compared using a soil‐block decay test. After 16 weeks of incubation, weight loss due to decay was greatest for red pine (23.2%) and larch (19.1%) and least for balsam fir (1.3%). Differences in the ability of H. irregulare to infect and saprophytically utilize substrate of these important tree species should prompt additional investigation of the relative risk posed to forests of the Great Lakes Region. 相似文献
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Deividas Valiunas Rasa Jomantiene Algirdas Ivanauskas Donatas Sneideris Marija Zizyte‐Eidetiene Jonathan Shao Zhao Yan Stefano Costanzo Robert E. Davis 《Forest Pathology》2019,49(6)
In order to devise a method for rapid detection of ‘Candidatus (Ca.) Phytoplasma pini’ and for distinguishing it rapidly from other phytoplasmas, we carried out preliminary sequencing of Lithuanian ‘Ca. Phytoplasma pini’ strain PineBL2 using Illumina (NGS) technology and targeted sequencing employing universal phytoplasma primers. We focused on two resulting chromosomal segments that contained a 16S rRNA gene and a translation elongation factor EF‐TU gene (tuf), respectively. Based on alignments of the ‘Ca. Phytoplasma pini’ gene sequences with the corresponding sequences of other phytoplasmas, we designed new primer pairs for PCR‐based detection of ‘Ca. Phytoplasma pini’. Because ‘Ca. Phytoplasma pini’ strains are expected to reside in the pine phloem in a very low titre, one might expect that they could be detected only by nested PCR. By contrast, the primers and PCR protocols designed in the current work enabled rapid direct PCR detection and identification of ‘Ca. Phytoplasma pini ’ by amplifying a 484 bp 16S rDNA segment and a 513 bp tuf gene fragment that contain regions unique to this phytoplasma . 相似文献
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The pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease (PWD), which is a major problem in East Asia and West Europe. Quick identification of PWN is needed to prevent the dispersal of PWD to healthy forests. Various detection methods of PWN have been developed using anatomical characters and molecular markers. These methods are not suitable for rapid diagnosis because it is difficult to distinguish B. xylophilus from the non‐pathogenic species Bursaphelenchus mucronatus based on morphological characters without expertise in nematode taxonomy and most PCR or isothermal amplification detection methods require time‐consuming processes. In this study, we developed an on‐site PWN detection method using a recombinase polymerase amplification (RPA) assay with a novel extraction buffer (DAP buffer). This new PWN detection method is able to extract genomic DNA from PWN in pinewood by simple buffer consisting of sodium hydrate, polyethylene glycol 200 and dimethyl sulfoxide in 10 min without using the experimental devices and able to distinguish between B. xylophilus and other Bursaphelenchus spp. by amplifying the species‐specific 5S rDNA fragment of B. xylophilus in 10 min. Taken together, our protocol can obtain the result for the detection of PWN in pine tree samples within 30 min. This result suggests that RPA/DAP assay is much faster, easier and cheaper than the conventional methods for detecting PWN. 相似文献
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J. Morgan Varner Francis E. Putz Joseph J. O&#x;Brien J. Kevin Hiers Robert J. Mitchell Doria R. Gordon 《Forest Ecology and Management》2009,258(11):2467-2474
Understanding the proximate causes of post-fire conifer mortality due to smoldering duff fires is essential to the restoration and management of coniferous forests throughout North America. To better understand duff fire-caused mortality, we investigated tree stress and radial growth following experimental fires in a long-unburned forest on deep sands in northern Florida, USA. We burned basal fuels surrounding 80 mature Pinus palustris Mill. in a randomized experiment comparing the effects of basal burning treatments on stem vascular meristems; surficial roots; root and stem combinations; and a non-smoldering control. We examined the effects of duration of lethal temperatures (>60 °C) on subsequent pine radial growth and root non-structural carbohydrates (starch and sugar). Duff and mineral soil temperatures in the experimental fires consistently exceeded 60 °C for over an hour following ignition, with lethal temperatures of shorter duration recorded 20 cm below the mineral soil surface. Duff heating was best explained by day-of-burn Oe horizon moisture (P = 0.01), although little variation was explained (R2 = 0.24). Post-fire changes in latewood radial increment in the year following fires was related to duration of temperatures >60 °C 10 cm deep in the mineral soil (P = 0.07), but explained little variability in post-fire growth (R2 = 0.17). In contrast, changes in non-structural carbohydrate content in coarse roots (2–5 mm diameter) 120 days following burning were more strongly correlated with the duration of lethal heating 5 cm below the mineral soil surface (P = 0.02; R2 = 0.53). Results from this study implicate the role of mineral soil heating in the post-fire decline of mature longleaf pine following restoration fires in sandy soils. 相似文献