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1.
Xyleborus glabratus attacks and systemic colonization by Raffaelea lauricola associated with dieback of Cinnamomum camphora in the southeastern United States 
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下载免费PDF全文 Laurel wilt, caused by Raffaelea lauricola, is responsible for extensive mortality of redbay and other American members of the Lauraceae in the southeastern United States. Raffaelea lauricola is a mycangial symbiont of the redbay ambrosia beetle (Xyleborus glabratus), and the beetle and fungus were accidentally introduced from Asia. Branch dieback of camphortree (Cinnamomum camphora), an Asian member of the Lauraceae, has been occasionally observed in areas where laurel wilt has decimated redbay populations, and R. lauricola was isolated from such camphortrees. However, the role of X. glabratus and R. lauricola in this branch dieback remains unclear. Examination of camphortrees on Jekyll Island, Georgia showed that healthy‐appearing trees and those with branch dieback had been attacked by X. glabratus, but the trees with branch dieback had four times as many beetle attacks. Raffaelea lauricola was routinely isolated from discoloured xylem near beetle tunnels in healthy trees and those with dieback. Single‐point inoculations with R. lauricola on stems of mature, healthy camphortree trees failed to induce wilt‐like symptoms or branch dieback, although areas of discoloration were scattered throughout the xylem, and R. lauricola was reisolated irregularly at various heights in some inoculated trees. In growth chamber experiments, single‐point inoculations with R. lauricola resulted in systemic colonization but no wilt symptoms or branch dieback in camphortree saplings. In contrast, inoculations at multiple points along the stem (simulating multiple attacks by the vector) caused branch dieback and wilt‐like symptoms, including a brownish, diffuse discoloration of the xylem. Camphortree appears to be more resistant than American species of Lauraceae to the vascular wilt caused by R. lauricola. The fungus does colonize camphortrees systemically, however, and can apparently cause branch dieback. This suggests that the fungus may provide brood material for X. glabratus in Asia as it does in the southeastern United States. 相似文献
2.
Shisham (Dalbergia sissoo) is an important multipurpose tree with great economic importance, but this tree has been devastated by dieback disease. Seedlings and asexually propagated (cuttings) plants were artificially inoculated with four fungi (Fusarium solani, Botryodiplodia theobromae, Curvularia lunata and Ganoderma lucidum) to evaluate the potential role of these fungi in shisham dieback disease. Results at 2 years revealed that highest disease was caused by inoculation of F. solani (31.39%), followed by B. theobromae (19.042%) and C. lunata (12.22%), but no dieback disease was caused by G. lucidum. During both years, seedlings exhibited greater susceptibility to disease (17.24%) compared to cuttings (7.83%). In particular, F. solani caused more disease in seedlings (46.18%) compared to cuttings (16.61%). With the F. solani inoculations, maximum disease rate was observed at 8 weeks post‐inoculation both in seedlings (77%) and in cuttings (31%), but the maximum disease increase was observed at 4–5 weeks post‐inoculation. Analysis of variance showed significant differences among the different fungi and also between seedlings and cuttings. F. solani can be considered as a major fungal pathogen contributing to dieback disease of shisham, and asexual propagation can reduce the severity of dieback. 相似文献
3.
Dawa Mndez‐lvarez Arantxa Rodríguez Yorleny Badilla‐Valverde Olman Murillo‐Gamboa 《Forest Pathology》2019,49(3)
Teak plantation productivity and economic value have risen significantly since 2000; however, teak dieback syndrome in commercial plantations is becoming worse every year. We isolated, characterized and identified the causal agents of teak dieback, based on morphological characteristics in culture and DNA sequencing. The pathogenicity of Lasiodiplodia theobromae and Fusarium proliferatum (separate and together) was confirmed in inoculations of teak elite genotypes, fulfilling Koch's postulates. To our knowledge, this is the first report of L. theobromae and F. proliferatumcausing teak dieback syndrome in Costa Rica. 相似文献
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Shailesh Pandey R Raja Rishi RSC Jayaraj Krishna Giri Rajesh Kumar Amit Pandey Ranjana Juwantha Sheeba Madaan Maneesh S. Bhandari 《Forest Pathology》2019,49(2)
Aquilaria malaccensis, categorized by IUCN as globally vulnerable, is in high demand in the Middle East and Asian markets for its unique resinous agarwood. In August 2015, symptoms of dieback were observed on A. malaccensis trees planted in the Medicinal and Aromatic Plant Garden, Panbari, Golaghat of the Assam Forest Department. The entire crowns of 70 trees showed complete leaf loss and severe dieback. Rotting at the collar region and of roots was also observed. Isolation from the infected roots consistently yielded Fusarium equiseti identified following standard laboratory procedures and analysis of the internal transcribed spacer (ITS) sequence of the ribosomal DNA. Symptoms of wilt, dieback and root rot were observed on 5‐month‐old Aquilaria seedlings 25 days after inoculation with the isolated fungus. This paper is the first report of F. equiseti causing wilt and dieback of A. malaccensis. 相似文献
6.
Distribution of dieback in Pinus nigra caused by Scleroderris lagerbergii Gr. in the Federal Republic of Germany. In the Federal Republic of Germany dieback of Pinus nigra caused by Scleroderris lagerbergii was observed in almost all States both along the coast and also in the interior of the country, on flat and on hilly situations. Killing of single trees or of whole stands is observed mainly in 8–25 years old Pinus nigra plantations. 相似文献
7.
L. Havrdová K. Novotná D. Zahradník V. Buriánek V. Pešková P. Šrůtka K. Černý 《Forest Pathology》2016,46(4):281-288
The impact of ash dieback caused by Hymenoscyphus fraxineus on 17 provenances of Fraxinus excelsior and one provenance of Fraxinus angustifolia was studied in an extensive field trial established in the Czech Republic prior to the H. fraxineus invasion in 1999. A difference in the level of resistance to ash dieback between the species was found: F. angustifolia was significantly less affected by the disease than F. excelsior. Moreover, particular provenances of F. excelsior showed important differences in the level of resistance to H. fraxineus. A relationship between the impact of ash dieback and altitude was also discovered – the provenances from altitudes above 600 m a.s.l. were less affected by the pathogen than were the provenances from lower areas. No difference in the impact of the disease among provenances of F. excelsior from different ecotopes (ravine, calcareous ravine and alluvial) was found. Substantial among‐tree variability in resistance to H. fraxineus was observed throughout the trial – promising genotypes (with crown defoliation up to 5%) were identified in all 18 tested provenances. In regard to this finding, it appears that the main source of resistance to the pathogen is probably at the individual genotype level in the trial. A secondary but massive attack by Hylesinus fraxini was identified in the trees that had been greatly damaged by ash dieback, and the beetle caused their health to deteriorate significantly. A significant negative effect of the presence of collar necroses caused by H. fraxineus and browse damage was also identified. 相似文献
8.
Air‐dried pseudosclerotia produced by the ash dieback pathogen Hymenoscyphus pseudoalbidus (anamorph: Chalara fraxinea) can survive up to 3 months. Under field conditions, they are capable of postponing fructification for 1 year. The implications of this observation for epidemiology and control of ash dieback are discussed. 相似文献
9.
Temporal evolution of collar lesions associated with ash dieback and the occurrence of Armillaria in Belgian forests 下载免费PDF全文
下载免费PDF全文 Ash dieback, caused by the fungus Hymenoscyphus fraxineus, has been observed in Europe for several years. In Belgium, the disease was first reported in 2010. Besides crown defoliation and dieback, collar lesions have sometimes been reported. To evaluate the prevalence and the progression of collar lesions and crown defoliation in ash dieback‐affected stands of various ages, a survey was conducted in 2013 and 2014 on 268 ash trees (Fraxinus excelsior) originating from 17 Walloon forest stands. The results showed that the proportion of trees with collar lesions greatly increased between June 2013 and September 2014 and that there appeared to be no significant link between a tree's diameter‐at‐breast height (DBH) and collar lesion occurrence. The mean percentage of defoliation increased in each forest stand across time, with observations conducted in September 2013 and 2014 showing a positive correlation with the mean percentage of trees with collar lesions. Molecular tests were carried out on 103 additional trees originating from 12 of the 17 stands to evaluate the occurrence of H. fraxineus and Armillaria spp. at the collar level. Most of the trees (98%) were infected by H. fraxineus. In contrast, only 41% of the samples were infected with Armillaria spp., most commonly A. gallica and A. cepistipes. This study discusses the role of Armillaria spp. and the rapid increase in the number of trees with collar lesions within the context of the evolution of ash dieback in Europe. 相似文献
10.
Ascocarp formation of Hymenoscyphus fraxineus on several‐year‐old pseudosclerotial leaf rachises of Fraxinus excelsior 下载免费PDF全文
下载免费PDF全文 T. Kirisits 《Forest Pathology》2015,45(3):254-257
The ash dieback pathogen Hymenosycphus fraxineus can form ascocarps on pseudosclerotial leaf rachises of Fraxinus excelsior not only in the year after leaf fall but also on older rachises, at least up to five growing seasons after the leaves have been shed. The significance of this finding for the epidemiology of ash dieback is discussed. 相似文献
11.
The presumed resistance of individual ash trees to ash dieback caused by invasive pathogen Hymenoscyphus fraxineus is an important issue for the maintenance of ash in European forests. All known studies regarding the resistance of ash trees to ash dieback were conducted in plantations and stands of F. excelsior; however, no such data exist for F. angustifolia. Crown damage assessments were performed over four consecutive years between 2009 and 2012 at a F. angustifolia clonal plantation in Hra??ica, Slovenia. Inoculation of H. fraxineus into the branches of the most and least damaged clones of F. angustifolia and leaf phenology assessments was performed to verify the presence of defence mechanisms that limit fungal growth or promote disease escape. Additionally, root collars of selected clones were inspected for fungal infections. The crown damage assessments showed considerable differences among F. angustifolia clones, indicating genetic variability in susceptibility to ash dieback. Crown dieback progressed significantly over the 4‐year time period; the mean crown damage of individual clones in 2012 varied between 16.7% and 83.8%. Significant differences among F. angustifolia clones were found in the inoculation trials and leaf phenology assessments. However, defence mechanisms such as early leaf flushing, early leaf shedding and the ability to inhibit pathogen growth in host tissues were not confirmed. High frequency of Armillaria spp. and H. fraxineus root collar infection demonstrated the need for whole tree inspection to determine causal agent of damages on individual ash trees. Armillaria spp. may be highly associated with ash decline epidemiology. 相似文献
12.
Giorgio Gusella Selene Giambra Gaetano Conigliaro Santella Burruano Giancarlo Polizzi 《Forest Pathology》2021,51(1):e12661
English walnut (Juglans regia) is an important nut crop worldwide and is currently considered emerging in Italy. Botryosphaeriaceae fungi cause symptoms including cankers, discoloration and dieback, and several species are reported across the world on walnut. In this study, symptomatic trees from an orchard in Southern Italy showing branch dieback, cankers, wood discoloration and gummosis were surveyed. Three different fungi from the Botryosphaeriaceae were consistently isolated from symptomatic tissues. Representative isolates were characterized using morphological and molecular approaches based on conidial morphology, optimum growth temperature and the comparison of DNA sequence data from the ITS, tef1‐α and tub2 loci. Three species were identified: Botryosphaeria dothidea, Neofusicoccum mediterraneum and Neofusicoccum parvum. Pathogenicity tests on detached fruits and potted plants showed that all three species were pathogenic. To our knowledge, this is the first report of these Botryosphaeriaceae species causing canker and dieback on English walnut in Italy. 相似文献
13.
Christ's thorn (Paliurus spina-christi Mill.) tree is an important and valuable forestry species and has significant potential in afforestation and reforestation systems. In recent years, dieback symptoms were observed on Paliurus spina-christi trees in Gilan-e Gharb region of Kermanshah province, west Iran. During 2020 to 2021, Christ's thorn trees that exhibit branch dieback symptoms were sampled for fungal isolations. The pathogenicity tests, biochemical assay of growth, acid production on creatine sucrose agar (CREA) medium and morphological and molecular investigations (ITS and β-tubulin regions) identified Paecilomyces formosus as a dieback causal agent. This is the first report of P. formosus pathogenicity on Paliurus spina-christi trees. Furthermore, disease severity was assayed on 11 tree species under three different temperatures 15, 25 and 35°C. Disease severity caused by all isolates on detached branches was greater at 35°C than at 15 and 25°C. This study presents the host range of this pathogen and showed that these potential hosts are prone to this pathogen under high temperatures, which forest trees experienced in recent decades. 相似文献
14.
[目的]在宝天曼森林原位建立降水减少(截雨)样地后,样地内的三桠乌药出现了顶端枯死,本研究从水和碳的角度,探讨三桠乌药顶端枯死的原因。[方法]2013年4月在宝天曼锐齿栎林原位建立了3块截雨样地,在2014年生长季干旱时,采用压力室、低压液流系统和蒽酮硫酸法测定了三桠乌药的水力系统特征和非结构性碳等指标。[结果]显示:(1)三桠乌药在截雨处理后出现了顶端枯死;三桠乌药最大导管长度约为60 cm,栓塞50%时的水势(P50)为-1.43 MPa,其木质部栓塞脆弱性较大。在截雨处理1年后生长季较干旱时,净光合速率、凌晨水势、中午水势显著低于对照,中午栓塞显著高于对照,且水力安全边际为负值。(2)三桠乌药气孔导度、蒸腾速率、叶面积、导管直径、边材比导率、叶片比导率显著下降,Huber值、导管密度显著升高;而叶片、韧皮部、木质部3个器官的可溶性糖、淀粉、总非结构性碳与对照差异不显著。[结论]水力失衡是三桠乌药顶端枯死的主要原因,而蒸腾面积、水分输导系统等的变化表明三桠乌药在缺水环境下进行了一定的适应性调节,但这些调节不足以使三桠乌药在缺水情况下避免水力失衡而导致的顶端枯死。 相似文献
15.
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
16.
Pathogenicity of Hymenoscyphus fraxineus and Hymenoscyphus albidus towards Fraxinus mandshurica var. japonica 下载免费PDF全文
下载免费PDF全文 The ash dieback pathogen Hymenoscyphus fraxineus proved to be pathogenic in a stem wound inoculation experiment on Fraxinus mandshurica var. japonica. In contrast, Hymenoscyphus albidus was proven non‐pathogenic for this host species. 相似文献
17.
Despite its importance as one of the most notorious, globally distributed, multihost plant pathogens, knowledge on the survival strategy of Phytophthora cinnamomi in seasonally dry climates is limited. Soil and fine roots were collected from the rhizosphere of severely declining or recently dead specimens of 13 woody species at 11 dieback sites and two dieback spots and from healthy specimens of five woody species at four dieback‐free sites in native forests, woodlands and heathlands of the south‐west of Western Australia (WA). Phytophthora cinnamomi was recovered from 80.4, 78.1 and 100% of tested soil, fine root and soil–debris slurry samples at the 11 dieback sites, in some cases even after 18‐month storage under air‐dry conditions, but not from the small dieback spots and the healthy sites. Direct isolations from soil–debris slurry showed that P. cinnamomi colonies exclusively originated from fine roots and root fragments not from free propagules in the soil. Microscopic investigation of P. cinnamomi‐infected fine and small woody roots and root fragments demonstrated in 68.8, 81.3 and 93.8% of samples from nine woody species the presence of thick‐walled oospores, stromata‐like hyphal aggregations and intracellular hyphae encased by lignitubers, respectively, while thin‐walled putative chlamydospores were found in only 21.2% of samples from five woody species. These findings were confirmed by microscopic examination of fine roots from artificially inoculated young trees of 10 woody species. It is suggested that (i) the main function of chlamydospores is the survival in moderately dry conditions between consecutive rain events and (ii) selfed oospores, hyphal aggregations, and encased hyphae and vesicles in infected root tissue of both host and non‐host species are the major long‐term survival propagules of P. cinnamomi during the extremely dry summer conditions in WA. 相似文献
18.
V. Queloz C. R. Grünig R. Berndt T. Kowalski T. N. Sieber O. Holdenrieder 《Forest Pathology》2011,41(2):133-142
Ash dieback caused by the mitosporic ascomycete Chalara fraxinea is a novel disease of major concern affecting Fraxinus excelsior and Fraxinus angustifolia in large parts of Europe. Recently, its teleomorph was detected and assigned to Hymenoscyphus albidus, which has been known from Europe since 1851. In this study, we present molecular evidence for the existence of two morphologically very similar taxa, H. albidus, which is lectotypified and Hymenoscyphus pseudoalbidus sp. nov. Differences were found between the species in the loci calmodulin, translation elongation factor 1‐α and the internal transcribed spacers of the rDNA genes, and strong differentiation was obtained with ISSR markers. It is likely that H. albidus is a non‐pathogenic species, whereas H. pseudoalbidus is a virulent species causing ash dieback. Genotyping herbarium specimens showed that H. pseudoalbidus has been present in Switzerland for at least 30 years prior to the outbreak of the epidemic. 相似文献
19.
First report of Lasiodiplodia theobromae and Pseudofusicoccum stromaticum causing dieback in Syzygium malaccense tree in Brazil 下载免费PDF全文
下载免费PDF全文 G. F. Silveira M. P. Melo J. W. M. Teixeira D. C. Viana J. D. C. Silva J. E. A. Beserra Jr 《Forest Pathology》2018,48(2)
Syzygium malaccense is a woody species, known as Malay apple, which is grown as an ornamental or for fruit production in Brazil, mainly in the northern and north‐eastern regions. A high incidence of dieback has been observed in Malay apple in ornamental situations, including streets and gardens. Morphological identification, sequencing analysis of TEF+ITS gene regions and a pathogenicity test confirmed that fungi in the Botryosphaeriaceae cause the disease. This is the first report of Lasiodiplodia theobromae and Pseudofusicoccum stromaticum causing dieback on S. malaccense trees in Brazil. 相似文献
20.
Pomegranate (Punica granatum) is native to Iran and neighbouring countries and is negatively affected by a wide range of diseases. Canker and dieback diseases caused by Cytospora punicae and members of the family Botryosphaeriaceae are the main trunk diseases on pomegranate. In summer 2017, progressive dieback of branches on some young pomegranate trees was observed in orchards of the Gorgan Region (Golestan province, Northeast Iran). Fungal colonies with similar colony colour were isolated from symptomatic tissues. The identity of the causal agent was determined as Neofusicoccum parvum, based on a polyphasic taxonomic approach including morphological features of conidiomata and phylogenetic inference based on the ITS‐rDNA region and translation elongation factor 1 alpha (tef1‐α) gene. Koch's postulates were fulfilled using an excised shoot method. This study provides the first report on the occurrence of N. parvum as a cause of branch canker on pomegranate in Iran. 相似文献