Search Results (34)

Detection of brown spot needle blight (BSNB) disease caused by the fungal pathogen Lecanosticta acicola (Thum.) Syd. has increased significantly at commercial loblolly pine (Pinus taeda L.) plantations across the southeastern United States in recent years. Historically, it has been a serious problem in longleaf pine (Pinus palustris Mill) during the grass stage of seedlings, when the environment is more conducive to fungal infection. However, since 2016, confirmed cases of the disease on loblolly pines have increased in several states, including AL, AR, FL, GA, LA, MS, SC, TN, and TX. We investigated the distribution pattern of confirmed cases of BSNB on loblolly pine between 2016 and 2023, identified site-specific factors, and evaluated the historical standardized precipitation index (SPI) value record over the past four decades. Our results showed that extended periods of above-normal SPI values are associated with BSNB spatial distribution patterns, particularly where the disease has been widely reported in AL, AR, LA, and MS. We observed significant reduction in tree height and dbh in severely infected versus healthy trees at the six study sites evaluated in 2023. Excessive rainfall and prolonged water saturation associated with historical 5-Year SPI values suggest that vulnerable loblolly pine seedlings (depending on genetic family) are more likely to be predisposed to L. acicola infection due to persistent stress from reduced soil nutrient flux and other physiological processes of the host. Understanding the effect of precipitation patterns on cases of BSNB is an important step toward preventing or minimizing the future impact of the disease on commercial plantations in the Southeast. Full article

Picea schrenkiana is a keystone species in Central Asian ecosystems currently threatened by climate-driven disease outbreaks. Here, we investigated the causal agent of needle blight and characterized the associated microbial dynamics. By integrating tissue isolation, Koch’s postulates, and high-throughput amplicon sequencing across a disease severity level, we confirmed Lirula macrospora as the etiological agent. Community analysis revealed that disease severity is the primary driver of succession, with alpha diversity peaks at the moderate infection stage. Notably, the abundance of Lirula surged from 2.56% in healthy needles to 65.10% in severe cases, displacing the core endophyte Phaeococcomyces, while potentially beneficial bacteria like Sphingomonas showed only transient enrichment. Furthermore, cross-kingdom co-occurrence network analysis revealed marked topological restructuring whereby the system reached a complex ecological “tipping point” during moderate stage before undergoing significant simplification. As the disease progressed, L. macrospora shifted from a peripheral node to a central hub, effectively dismantling the native microbial network. We conclude that L. macrospora infection triggers a cascading collapse of the needle microbiome, driving a phase shift from a healthy homeostasis to a pathogen-dominated state. These findings elucidate the critical mechanisms of pathogen-microbiome interactions and provide a theoretical basis for the ecological management of P. schrenkiana forests. Full article

Diplodia shoot blight is an opportunistic fungal pathogen infesting many conifer species and it has a global distribution. Depending on the duration and severity of the disease, affected needles appear yellow (chlorotic) for a brief period before becoming red or brown in colour. These symptoms can occur on individual branches or over the entire crown. Aerial sketch-mapping or the manual interpretation of aerial photography for tree health surveys are labour-intensive and subjective. Recently, however, the application of deep learning (DL) techniques to detect and classify tree crowns in high-spatial-resolution imagery has gained significant attention. This study evaluated two complementary DL approaches for the detection and classification of Pinus radiata trees infected with diplodia shoot blight across five geographically dispersed sites with varying topographies over two acquisition years: (1) object detection using YOLOv12 combined with Segment Anything Model (SAM) and (2) pixel-level semantic segmentation using U-Net, SegFormer, and EVitNet. The three damage classes for the object detection approach were ‘yellow’, ‘red-brown’ (both whole-crown discolouration) and ‘dead tops’ (partially discoloured crowns), while for the semantic segmentation the three classes were yellow, red-brown, and background. The YOLOv12m model achieved an overall mAP50 score of 0.766 and mAP50–95 of 0.447 across all three classes, with red-brown crowns demonstrating the highest detection accuracy (mAP50: 0.918, F1 score: 0.851). For semantic segmentation models, SegFormer showed the strongest performance (IoU of 0.662 for red-brown and 0.542 for yellow) but at the cost of longest training time, while EVitNet offered the most cost-effective solution achieving comparable accuracy to SegFormer but with a superior training efficiency with its lighter architecture. The accurate identification and symptom classification of crown damage symptoms support the calibration and validation of satellite-based monitoring systems and assist in the prioritisation of ground-based diagnosis or management interventions. Full article

The aim of this study was to determine fungal diversity and composition in an area of high host diversity and identify the organisms involved in the appearance of symptoms in Pinus needles. Asymptomatic and symptomatic live needle samples were obtained from different Pinus spp. in an arboretum with confirmed presence of brown spot needle blight. The samples were analysed using high-throughput sequencing of fungal ITS2rDNA. Ascomycota dominated all samples, with Lophodermium as the most abundant genus, although it showed lower representation in symptomatic needles. Other genera with recognised pathogenic potential, including Lecanosticta, Pestalotiopsis, Cyclaneusma, Rhizosphaera, Neophysalospora, and Cenangium, were also detected, whereas the Dothistroma genus was absent despite its presence in the region. Alpha diversity was higher in asymptomatic needles, with a significant difference only for the Shannon index, while Bray–Curtis dissimilarity revealed significant shifts in community composition between needle types. Functional guilds were dominated by pathotroph–saprotroph trophic mode, and the functional guild ‘plant pathogen’ was the most abundant across samples. These findings identify fungal genera associated with symptomatic and asymptomatic needles and provide guidance for future targeted isolation and detailed morphological and molecular identification using more resolutive techniques, enabling a deeper understanding of pathogenic community presence and their potential synergistic interactions. Full article

This paper describes a study conducted to investigate the spread of Lecanosticta acicola, the cause of brown spot needle blight (BSNB), in Pinus mugo dune forests in the Polish Baltic region. Between 2023 and 2025, 22 sites were surveyed, including coastal forests and some ornamental plantings. Characteristic BSNB symptoms were recorded in 21 of the 22 locations, and the pathogen’s presence was confirmed through culture isolation and species-specific PCRs. The disease was most severe in compact, monospecific P. mugo thickets, where defoliation exceeded 30%, while mixed stands with P. sylvestris or occasionally P. nigra exhibited lower infection rates. A degree of infection of P. sylvestris was observed in proximity to heavily infected P. mugo stands, confirming interspecific transmission under high inoculum pressure. We observed nearly ubiquitous occurrence of L. acicola along the coast, suggesting an advanced stage of establishment. However, the very recent detection of the pathogen at the westernmost sites indicates ongoing westward spread. These findings highlight the vulnerability of coastal P. mugo populations and underline the need for genetic diversity data that would allow us to trace the origins and pathways of L. acicola spread in the south-eastern Baltic region. The potential adaptation of the pathogen to P. sylvestris in the future would pose a serious risk for Polish forestry. Full article

The aim of this study was to identify the causative agent of bacterial blight and basal glume rot of winter wheat that appeared in Serbia in 2023. To characterize the isolated bacteria (eight isolates in total), their cultural, biochemical, pathogenic, and genetic characteristics were examined. Based on the results of the LOPAT test, the isolates were classified into Pseudomonas Group Ia. The syrB and syrD genes were simultaneously detected in six wheat isolates—P0123, P0223, P0323, P0423, P0523, and P0823—while two isolates, P1123 and P1323, lacked both genes. Multilocus sequence typing (MLST) of the gapA, gltA, gyrB, and rpoD genes identified six isolates (P0123, P0223, P0323, P0423, P0523, and P0823) as Pseudomonas syringae pv. atrofaciens, whereas the remaining two isolates (P1123 and P1323) were most closely related to P. poae. Phylogenetic analysis revealed three genetically heterogeneous subgroups of P. syringae pv. atrofaciens among the wheat isolates from Serbia. Pathogenicity tests demonstrated that wheat isolates are able cause disease on wheat seedlings using three different inoculation methods: spraying the entire seedling, trimming the leaves before spraying, and wounding the leaves with multiple needles followed by spraying. Overall, isolates P0123 and P0423 were identified as the most virulent, inducing pronounced blight symptoms on wheat seedlings. In contrast, isolates P1123 and P1323 were weakly virulent and are therefore considered to be secondary or accompanying factors in plants already infected with more aggressive isolates, rather than primary pathogens responsible for disease development. This study contributes to a deeper understanding of the ecology, distribution, and pathogenic potential of bacterial communities associated with wheat blight disease in Serbia. Full article

Chinese pine, Pinus tabuliformis, is one of the most important garden plants in northern China, and the planting of this species is of great significance for the improvement of the ecological environment. In this study, different fungi were isolated and purified from diseased Pinus tabuliformis samples collected in Xi’an city, Shaanxi Province. Of these fungal isolates, only one (isolate AP-3) was pathogenic to the healthy host plant. The pathogenic isolate was identified as Fusarium acuminatum by morphological characteristics and ITS and TEF-1α sequence analyses. The optimal growth conditions for this isolate were further analyzed as follows: Optimal temperature of 25 °C, pH of 11, soluble starch and sodium nitrate as the most preferred carbon and nitrogen sources, respectively. By combining Oxford Nanopore Technologies (ONT) long-read sequencing with Illumina short-read sequencing technologies, we obtained a 41.50 Mb genome assembly for AP-3, with 47.97% GC content and 3.04% repeats. This consisted of 14 contigs with an N50 of 4.64 Mb and a maximum length of 6.45 Mb. The BUSCO completeness of the genome assembly was 98.94% at the fungal level and 97.83% at the Ascomycota level. The genome assembly contained 13,408 protein-coding genes, including 421 carbohydrate-active enzymes (CAZys), 120 cytochrome P450 enzymes (CYPs), 3185 pathogen-host interaction (PHI) genes, and 694 candidate secreted proteins. To our knowledge, this is the first report of F. acuminatum causing needle blight of P. tabuliformis. This study not only uncovered the pathogen responsible for needle blight of P. tabuliformis, but also provided a systematic analysis of its biological characteristics. These findings provide an important theoretical basis for disease control in P. tabuliformis and pave the way for further research into the fungal pathogenicity mechanisms and management strategies. Full article

Dothistroma needle blight (DNB) is one of the most significant diseases of conifers, causing premature defoliation, growth reduction, and, in extreme cases, mortality. Histological analysis was undertaken on inoculated seedlings of three different seed sources of Pinus sylvestris L. to investigate the process of infection and degradation of needle tissue on this host species. Seedlings were inoculated using a single spore isolate of Dothistroma septosporum (Doroguine) M. Morelet (D636) from northern Scotland. Mesophyll degradation in the needles occurred by four weeks after inoculation; collapse of mesophyll, bundle sheath tissues, and tracheids by five weeks; and eruption of fruiting bodies in near proximity to stomatal openings by six weeks. Significantly greater collapse of mesophyll during the early stages of infection occurred in the Austrian provenance compared with the United Kingdom provenance, although in the later stages of infection, this difference disappeared. Furthermore, disease severity, assessed as the proportion of needles with D. septosporum conidiomata on each tree, was not significantly different between seed sources. Full article

Pine needle blight of Pinus massoniana caused by pathogens of the Pestalotiopsis genus is a destructive disease worldwide, especially in young forests. Chemical fungicides accelerate the formation of resistant strains among plant pathogenic fungi, which makes microbial biocontrol particularly important. In this study, we identified Neopestalotiopsis camelliae-oleiferae as a new pathogen of pine needle blight in P. massoniana via pathogen isolation, inoculation, pathogenicity assays, morphology observations, and multilocus phylogenetic analyses of the ITS, TEF1, and TUB2 regions. PSM-6, an endophytic bacterium, was subsequently isolated from pine needles and was shown to have excellent antagonistic activity against N. camelliae-oleiferae in vitro. Based on the morphology, physiology, and molecular analysis, we identified this strain as P. silvicola. The extracellular secondary metabolites of PSM-6 were further proven to cause the shrinkage and collapse of pathogen hyphae. The decreased disease index and mortality indicated that pretreatment with PSM-6 may effectively protect pine seedlings from pathogen infection. In addition, PSM-6 exhibited broad-spectrum antifungal activity in several phytopathogenic fungi, including Fusarium graminearum, Botrytis cinerea, and Verticillium dahliae. These findings establish PSM-6 as a promising biocontrol agent, offering an environmentally friendly alternative to chemical fungicides for managing pine needle blight and other fungal diseases. Full article

In June 2020, needle blight symptoms on Pinus thunbergii were discovered in Bazhong City, Sichuan Province, China. Fungal isolates were obtained from the pine needles of P. thunbergii. After examining morphological characteristics and conducting multi-locus (ITS, ACT, TUB2 and RPB2) phylogenetic analyses, the isolates SC1–SC5 were determined to be a new species, Biscogniauxia sinensis. Genealogical Concordance Phylogenetic Species Recognition with a pairwise homoplasy index test was used to further verify the results of the phylogenetic analyses. The morphology and phylogenetic relationships between this new species and other related Biscogniauxia species were discussed. To our knowledge, this is also the first report of Biscogniauxia sinensis associated with pine needle blight on P. thunbergii in China. The needle damage of P. thunbergii associated with Biscogniauxia sinensis will detrimentally affect the carbon absorption and photosynthetic efficiency of P. thunbergii, further reduce the absorption of nutrients by Japanese black pine and may lead to the imbalance of pine forest conditions, which will have a negative impact on the forest ecological system. Full article

Pinus massoniana Lamb. is an important, common afforestation and timber tree species in China. Species of Pestalotiopsis are well-known pathogens of needle blight. In this study, the five representative strains were isolated from needle blight from needles of Pi. massoniana in Nanjing, Jiangsu, China. Based on multi-locus phylogenetic analyses of the three genomic loci (ITS, TEF1, and TUB2), in conjunction with morphological characteristics, a new species, namely Pestalotiopsis jiangsuensis sp. nov., was described and reported. Pathogenicity tests revealed that the five representative strains of the species described above were pathogenic to Pi. massoniana. The study revealed the diversity of pathogenic species of needle blight on Pi. massoniana. This is the first report of needle blight caused by P. jiangsuensis on Pi. massoniana in China and worldwide. This provides useful information for future research on management strategies of this disease. Full article

Diplodia tip blight, caused by Diplodia sapinea (=Sphaeropsis sapinea), are widely distributed in Honghuaerji, Inner Mongolia, China, causing severe damage on natural Mongolian pine (Pinus sylvestris var. mongolica). D. sapinea is an endophyte that becomes pathogenic under conditions of drought, hail damage, or temperature-associated stress. The role of the endophytic community inhabiting different pine tissues in the expression of disease is still unknown. In this study, the diversity and community structure of endophytic fungi among asymptomatic and symptomatic Mongolian pine were detected using culture-based isolation and high-throughput sequencing (HTS), and the potential antagonistic endophytes against D. sapinea were also screened. The results indicated that 198 and 235 strains of endophytic fungi were isolated from different tissues of symptomatic and asymptomatic Mongolian pine, respectively. D. sapinea was the most common endophyte isolated from the current-year needles and shoots of symptomatic trees, and Diplodia was also the most common in the HTS data. There were no significant differences in the endophytic fungal species richness among asymptomatic and symptomatic trees, but there were differences observed within specific sampled tissues. The ANOSIM analysis confirmed that the endophytic fungi community structure significantly differed between sampling tissues among symptomatic and asymptomatic Mongolian pine. Furthermore, the antagonism study revealed Penicillium fructuariae-cellae with the ability to inhibit the growth of D. sapinea in vitro, and the potential performance of this fungus, acting as biological control agent, was evaluated under greenhouse. Our findings can pave the way to a better understanding of the interactions between D. sapinea, other endophytic fungi and their hosts, and provide helpful information for more efficient disease management strategies. Full article

Black spot needle blight is a minor disease in Mongolian Scots pine (Pinus sylvestris var. mongolica) caused by Pestalotiopsis neglecta, but it can cause economic losses in severe cases. Sodium pheophorbide a (SPA), an intermediate product of the chlorophyll metabolism pathway, is a compound with photoactivated antifungal activity, which has been previously shown to inhibit the growth of P. neglecta. In this study, SPA significantly reduced the incidence and disease index and enhanced the chlorophyll content and antioxidant enzyme activities of P. sylvestris var. mongolica. To further study the molecular mechanism of the inhibition, we conducted a comparative proteomic analysis of P. neglecta mycelia with and without SPA treatment. The cellular proteins were obtained from P. neglecta mycelial samples and subjected to a tandem mass tag (TMT)-labelling LC-MS/MS analysis. Based on the results of de novo transcriptome assembly, 613 differentially expressed proteins (DEPs) (p < 0.05) were identified, of which 360 were upregulated and 253 downregulated. The 527 annotated DEPs were classified into 50 functional groups according to Gene Ontology and linked to 256 different pathways using the Kyoto Encyclopedia of Genes and Genomes database as a reference. A joint analysis of the transcriptome and proteomics results showed that the top three pathways were Amino acid metabolism, Carbohydrate metabolism, and Lipid metabolism. These results provide new viewpoints into the molecular mechanism of the inhibition of P. neglecta by SPA at the protein level and a theoretical basis for evaluating SPA as an antifungal agent to protect forests. Full article

Fungal diseases such as root rot and leaf blight cause substantial losses in coastal pine (Pinus thunbergii Parl.) seedling production, which hinders afforestation/forest restoration programs. We isolated and identified Fusarium oxysporum and Alternaria alternata as the causal agents of root rot and needle blight diseases and investigated the biocontrol efficacy against the fungal pathogens and growth promotion of coastal pine seedlings using Bacillus velezensis CE 100. The bacterium produced the hydrolytic enzymes chitinase, β-1,3-glucanase, and protease enzymes, and the crude enzyme fraction of the biocontrol strain caused the deformation of the fungal cell wall and antagonized F. oxysporum and A. alternata, causing respective inhibition of spore germination by 91.0% and 85.9% and mycelial growth by 58.3% and 54.3%, at a concentration of 1000 µL/mL. Consequently, the bacterial treatment improved the survival rate of seedlings 1.9 times relative to the control group. The bacterium secreted indole-acetic acid (IAA) phytohormone and enhanced root growth and absorption of nutrients, which notably enhanced the biomass production of coastal pine seedlings. Therefore, these results provide evidence that B. velezensis CE 100 is an effective antifungal and growth-promoting bacterium that can facilitate the production of high-quality coastal pine seedlings for the restoration and establishment of coastal forests. Full article

The international plant trade results in the accidental movement of invasive pests and pathogens, and has contributed significantly to recent range expansion of pathogens including Dothistroma septosporum. Seeds are usually thought to present a lower biosecurity risk than plants, but the importation of Pinus contorta seeds from North America to Britain in the mid-1900s, and similarities between British and Canadian D. septosporum populations suggests seeds could be a pathway. Dothistroma septosporum has not been isolated from seeds, but inadequately cleaned seed material could contain infected needle fragments. This case study investigated whether cone kilning, and wet and dry heat treatments could reduce D. septosporum transmission without damaging seed viability. Pinus needles infected with D. septosporum were incubated alongside cones undergoing three commercial seed extraction processes. Additional needles were exposed to temperatures ranging from 10 to 67 °C dry heat for up to 48 h, or incubated in water heated to between 20 and 60 °C for up to one hour. Pinus sylvestris seeds were exposed to 60 and 65 dry heat °C for 48 h, and further seed samples incubated in water heated to between 20 and 60 °C for up to one hour. Dothistroma septosporum survived the three kilning processes and while seeds were not damaged by dry heat exceeding 63.5 °C, at this temperature no D. septosporum survived. Wet heat treatments resulted in less than 10% pathogen survival following incubation at 40 °C, while at this temperature the seeds suffered no significant impacts, even when submerged for one hour. Thus, commercial seed kilning could allow D. septosporum transmission, but elevated wet and dry heat treatments could be applied to seed stock to minimise pathogen risk without significantly damaging seed viability. Full article