Diseased Trees Research Articles

Complete genome sequence of a novel virus belonging to the genus Badnavirus in jujube (Ziziphus jujuba Mill.) in China.

The genome sequence of a novel circular DNA virus related to members of the genus Badnavirus was identified in diseased jujube trees by high-throughput sequencing and verified by conventional Sanger sequencing of cloned PCR products. The name "jujube badnavirus WS" (JuBWS) is proposed for this virus. Diseased jujube leaves showed yellow mosaic and malformation symptoms, with round chlorotic spots found on diseased fruit. The genome of this virus has a length of 6450 nt and has a typical badnavirus genomic structure with three open reading frames (ORFs). JuBWS was identified as a novel badnavirus based on nucleotide differences in the RNase (RT + RNase H) coding region of ORF3. The JuBWS sequence showed 70.48-76.41% nucleotide sequence identity to other known badnaviruses, thus meeting the taxonomic criterion for establishing a new species within the genus Badnavirus. This study suggested that the novel badnavirus might be a pathogen associated with jujube mosaic disease, and this will be investigated in the future.

A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the detection of plum viroid I (PlVd-I)

Plum viroid I (PlVd-I) is found in marbling and corky flesh diseased plum trees in South Africa. In this study a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the high-throughput detection of PlVd-I was developed. This assay can be performed on crude extracts and detection can either be a pH dependent colorimetric reaction or a real-time fluorescent signal reaction. The false discovery rate was shown to be low and no decrease in sensitivity was detected compared to RT-PCR. The RT-LAMP assay allows for the fast and cost-effective detection of PlVd-I that will curtail the distribution of infected plant material.

Penyakit Busuk Pangkal Batang dan Performa Produktivitas Kelapa Sawit

Yield gaps can occur due to land degradation, climate change, and increased pest and disease attacks. Basal stem rot disease is a major problem in oil palm cultivation. This study utilized secondary data, namely production data for 2003-2016, tree population data and the incidence of Ganoderma disease observed in 2016 in plantation company in South Lampung. The yield gap is measured using the productivity performance index, namely the ratio between actual productivity and potential productivity of land with S3 land suitability. The results showed that: (1) The tree mortality rate in young oil palm plants was significantly lowest at 0.67 trees per year compared to the juvenile, adult and old age categories ranging from 1.6 to 1.9 trees per ha per year. The number of dead and diseased trees increases in linear regression with increasing age; (2) Ganoderma attack in the heavy category was more common in juvenile, mature, and old plants. In young plants, the incidence of severe attack was 0.4 trees per ha, while in juvenile, mature and old plants it ranged from 1-2 plants per ha and there was no significant difference between juvenile, adult, and old age categories. There was no significant difference in the incidence of light attack between age categories, ranging from 1.6 to 2.6 trees per ha; (3) Heavy attack of Ganoderma affects yield performance linearly. Plantation groups with different generations of planting years showed different yield trends. The two plantation groups both reached peak production of 18 FFB/ha/year which was achieved at different ages. Yield declines occur more rapidly in the next generation of replanted gardens as a degeneration symptom. Key words : Degeneration, Ganoderma, incidence, performance, replanting, oil palm

Detection of citrus Huanglongbing (HLB) based on the HLB-induced leaf starch accumulation using a home-made computer vision system

Citrus Huanglongbing (HLB) is a highly destructive and transmissible citrus disease spread by insects. As it has no effective treatment, there is an urgent need for a rapid HLB detection method that can be applied in orchards to remove the diseased trees. In this research, the contribution of two symptoms, based on HLB-induced starch accumulation, were evaluated to HLB detection using a home-made computer vision system with two imaging modes. The reflection imaging mode was used to detect blotchy mottles symptoms. A 660 nm light source was used and the absorption of different wavelengths by chlorophyll and lutein was measured. The transmission imaging was designed to detect abnormal starch accumulation within the leaf. An image was taken with 590 nm polarised light penetrating the leaf, then the angle of linear polarisation (AoLP) was calculated by the Stokes vector. The AoLP reflects the ability of the internal leaf components to rotate polarised light. The polarisation angle reflects the starch content of the leaves and determines their disease status. Multi-layer perceptron (MLP), random forest (RF), and logistic regression (LR) classifiers were then evaluated. The RF classifier performed better in the reflection experiment, with a classification accuracy of 96.67%. In the transmission experiment, the LR classifier had 88.33% recognition rate. The results show that HLB-induced starch accumulation contributes to the visual detection of HLB. This research supports the high accuracy and portability of HLB detection equipment and it has great practical importance for preventing and controlling of HLB disease. • A home-made computer vision system with two imaging modes was designed. • Computer vision enhanced two symptoms caused by HLB-induced starch accumulation. • Reflection imaging was effective in highlighting blotchy mottles symptoms of HLB. • The optical activity of starch in HLB + leaf was detected by transmission imaging. • The contribute of HLB-induced starch accumulation to HLB detection was confirmed.

EFFECT OF GUMMOSIS CAUSED BY PHYTOPHTHORA SPP. ON LEAF AREA AND TRUNK SIZE OF CITRUS IN DISTRICT SARGODHA, PAKISTAN

Gummosis disease of citrus, caused by Phytophthora spp. is one of the most devastating diseases of citrus in Pakistan. Considering the menace of this disease, the present study was conducted to determine the disease incidence and its effect on the trunk size and leaf area of affected plants. A comprehensive survey was conducted in 75 citrus orchards in 3 tehsils (Sargodha, Bhalwal, and Kot Momin) of the district Sargodha for the prevalence of the disease. The diseased plants were marked from each orchard, trunk size was measured and leaf area was recorded using leaf area meter. The leaves from diseased plants of tehsil Sargodha showed the highest leaf area with an average of about 2685 mm2 followed by Bhalwal 2548 mm2. There was a huge difference in the trunk size of healthy and diseased trees. The highest average healthy trunk size (102 cm) was recorded in Kot Momin while the diseased trunk in Bhalwal was found 9 cm in size. Healthy leaf area and trunk size were not significantly different from tehsil to tehsil, but diseased trees were significantly different from each other at P0.05. Gummosis is a widespread disease in citrus growing areas and continues to gain importance as a constraint in citrus production. Therefore, concerted efforts should be implemented towards educating farmers and extension personnel about the disease's spread and management.

First Report of a New Disease Caused by Fusarium tricinctum on Apple Tree in China.

First Report of a New Disease Caused by Fusarium tricinctum on Apple Tree in China.

Identification, Biological Characteristics of Pestalotiopsis diospyri and Its Sensitivity to Fungicides

Persimmon canker disease on stems caused by pathogens affects its growth and yield, leads to economic losses, thus it is important to investigate the pathogen in detail to find an effective control method. In this paper, samples from diseased persimmon trees in Yunnan were collected to isolate and purify the pathogen, and its biological characteristics were studied. In detail, its morphology was observed and molecular identified. The effects of different carbon and nitrogen sources, temperature, pH and light condition on its growth were analyzed, and the toxicities of 6 fungicides to the pathogen were compared. In the results, the pathogens were identified as Pestalotiopsis diospyri, the optimum conditions for its mycelium growth were on persimmon stem decoction medium, temperature 30 °C, light illumination for 24 h and pH at 4. The most suitable carbon and nitrogen sources were glucose and sodium nitrate, respectively. The sensitivity test of six fungicides to P. diospyri showed different degrees, the EC50 values of tebuconazole, azoxystrobin, chlorothalonil, difenoconazole, prochloraz, and carbendazim were 0.212, 0.313, 4.921, 0.552, 0.035 and 6.175 μg/mL, respectively, revealing that P. diospyri was the most sensitive to prochloraz. In conclusion, P. diospyri grow fastest in acidic and well-lit environments, and prochloraz can be used as a protential fungicide for the treatment and prevention of the disease. This paper provides a theoretical basis for further research and field experiment.

High Altitudes Limit The Incidence of Huanglongbing snd Its Vector, Diaphorina Citri, in Citrus Orchards

Abstract Citrus fruit are important crops in many regions of the world and are valuable sources of carbohydrates, fibre and health-promoting compounds. Like other crops, production of these fruits is affected by a range of pests and pathogens that can affect the sustainable development of citriculture. The most devastating of these is huanglongbing (HLB), a bacterial disease caused by species of liberibacters, pathogens that are spread by insect vectors. Currently, there is no remedy for HLB, and management relies on the use of disease-free seedlings, the rouging of diseased trees, and pesticides to suppress populations of vectors. Our studies on HLB in Indonesia and Bhutan have shown that citrus grown at higher altitudes (above 1000–1200 m ASL) can remain free from the main vector of the disease, the psyllid Diaphorina citri, despite climatic conditions at these altitudes being favourable for the insect. Thus, sustainable production of citrus at these altitudes without the use of polluting agrochemicals may be possible. However, this would be dependent on the production and use of HLB-free propagation material, strict control on the movement of trees into these areas and the adoption of appropriate agronomic practices for the control of other pests and pathogens.

Canopy spectral reflectance detects oak wilt at the landscape scale using phylogenetic discrimination

The oak wilt disease caused by the invasive fungal pathogen Bretziella fagacearum is one of the greatest threats to oak-dominated forests across the Eastern United States. Accurate detection and monitoring over large areas are necessary for management activities to effectively mitigate and prevent the spread of oak wilt. Canopy spectral reflectance contains both phylogenetic and physiological information across the visible near-infrared (VNIR) and short-wave infrared (SWIR) ranges that can be used to identify diseased red oaks. We develop partial least square discriminant analysis (PLS-DA) models using airborne hyperspectral reflectance to detect diseased canopies and assess the importance of VNIR, SWIR, phylogeny, and physiology for oak wilt detection. We achieve high accuracy through a three-step phylogenetic process in which we first distinguish oaks from other species (90% accuracy), then red oaks from white oaks (Quercus macrocarpa) (93% accuracy), and, lastly, infected from non-infected trees (80% accuracy). Including SWIR wavelengths increased model accuracy by ca. 20% relative to models based on VIS-NIR wavelengths alone; using a phylogenetic approach also increased model accuracy by ca. 20% over a single-step classification. SWIR wavelengths include spectral information important in differentiating red oaks from other species and in distinguishing diseased red oaks from healthy red oaks. We determined the most important wavelengths to identify oak species, red oaks, and diseased red oaks. We also demonstrated that several multispectral indices associated with physiological decline can detect differences between healthy and diseased trees. The wavelengths in these indices also tended to be among the most important wavelengths for disease detection within PLS-DA models, indicating a convergence of the methods. Indices were most significant for detecting oak wilt during late August, especially those associated with canopy photosynthetic activity and water status. Our study suggests that coupling phylogenetics, physiology, and canopy spectral reflectance provides an interdisciplinary and comprehensive approach that enables detection of forest diseases at large scales. These results have potential for direct application by forest managers for detection to initiate actions to mitigate the disease and prevent pathogen spread.

Risk Assessment of Cardiovascular Diseases Using kNN and Decision Tree Classifier

As per the information provided by WHO, most of the people die from the cardiovascular disease. In 2019, almost 32% of the global deaths were due to cardiovascular diseases, out of which 85% were because of heart attacks and strokes. Hence, it is very important to predict the chances and risk of cardiovascular disease event, to prevent any damage in future. Cardiovascular diseases are the disorders of blood vessels supplying blood to heart, brain and different parts of the body. There are different causes of cardiovascular diseases, which can be quantified with the help of different features and with supporting attributes like age of the person, any diseases like diabetes, blood pressure etc., the risk of the cardiovascular disease can be assessed to prevent the further losses. Machine learning approach is very useful in these circumstances, where quantified data values are available in terms of data set. Machine learning techniques can be used to find the risk of cardiovascular disease. Here, we are proposing to use the two machine learning classifiers such as kNN and decision tree. kNN helps us to find the possibility of cardiovascular disease and decision tree helps us to classify the type of the cardiovascular disease with the risk involved. This approach is very useful, as decision tree is one of the most accurate classifiers, which also helps us to identify the specific cardiovascular disease that can be the future event based on feature values. This proposed methodology is justified with proper research gap stating the important of the proposed architecture and implementation results, which gives effective way for assessing the risk of cardiovascular disease.

Prevalence of Erectile Dysfunction in Patients With Abdominal Aortic Aneurysm: An Exploratory Study.

IntroductionErectile dysfunction (ED) is defined as the recurrent inability to achieve and maintain a satisfactory erection for sexual intercourse. Many studies have highlighted that ED shares common cardiovascular risk factors with cardiovascular disease. No data are reported about the prevalence of ED in patients with the abdominal aortic aneurysm (AAA). The aim of our study was to investigate the preoperative information given about sexual functions of patients undergoing endovascular aneurysm repair (EVAR) and to compare it with the presence and severity of steno-occlusive atherosclerotic lesions of the pelvic arterial tree at pre-operative Computed Tomography Angiography (CTA).MethodsWe prospectively enrolled all men patients who underwent elective EVAR from September to November 2021. Preoperative ED was evaluated using the International Index of Erectile Function (IIEF-5) questionnaire. Preoperative imaging was routinely performed with CTA scan of the abdominal aorta and iliac-pelvic district. An innovative score of pelvic arterial disease associated to AAA was defined, dividing the iliac district in 4 zones attributing a grading of severity for each zone bilaterally (score ranges 0–24). Linear regression analysis was used to correlate IIEF-5 score to anatomical score of pelvic arterial steno-occlusive disease.ResultsA total of 25 patients were enrolled. Median age was 74 ± 5.3 years. IIEF-5 average score was 14.8 ± 7.1. Eight cases (32%) had severe ED; one case (4%) had moderate, five patients (20%) had mild to moderate ED; five patients (20%) had mild ED, and 6 (24%) patients had no ED. CTA evaluation revealed an average anatomical score of 7.9 ± 4.5. Pelvic disease was considered moderate-severe in 20 cases (80%) and not significant in 20% (five cases). Linear regression analysis confirmed the hypothesis that a more diseased pelvic arterial tree was correlated to a more severe ED (Y = −1.531* × + 26.35 [slope CI: −1.946 to −1.117, p < 0.0001]).ConclusionAlthough typically unreported, the prevalence of ED associated to AAA was found to be high. A vasculogenic origin of ED in patients with AAA is plausible and may be easily confirmed by the evaluation of pelvic arterial distribution at angio-CT performed for EVAR planning. Our proposed “MAPPING AND SCORING SHEET” may help to identify the vasculogenic origin of ED in AAA patients.

Trunk sap rot of Japanese cedar (Cryptomeria japonica) caused by Fomitiporella sinica

ABSTRACT Trunk rot caused by the wood decay fungus Fomitiporia torreyae is a serious disease of Japanese cedar. The rot is characterized by white sap rot with brown zone lines and vertical depressions on the trunk. During our field investigations on this disease, we found another sap rot on Japanese cedar, characterized by white rot with brown zone lines, with or without less obvious depressions on the trunk. The results of phylogenetic analysis of the most frequently isolated fungus from the diseased trees and morphological observation of basidiocarps previously identified as Fomitiporella umbrinella showed that both represented Fomitiporella sinica. Our inoculation tests using Japanese cedar showed that F. sinica caused longer discoloration in sapwood compared with control treatment. Therefore, we concluded that F. sinica was the cause of trunk rot on Japanese cedar as reported for F. torreyae, but trunk depressions were not obvious in the trees infected with F. sinica. Moreover, branch scars were found around the middle of decaying parts of diseased trees infected with F. sinica, and infection with this fungus was assumed to occur via dead branches or pruning scars.

Survey of Oomycetes Associated with Root and Crown Rot of Almond in Spain and Pathogenicity of Phytophthora niederhauserii and Phytopythium vexans to ‘Garnem’ Rootstock

From 2018 to 2020, surveys of oomycetes associated with root and crown rot of almond (Prunus dulcis) were conducted on diseased young almond trees in commercial orchards and nurseries in six provinces of Spain. A total of 104 oomycete isolates were obtained from plant and soil samples, which h were identified by sequencing the internal transcribed spacer (ITS) region of the ribosomal DNA. Diverse species belonging to the genera Globisporangium, Phytophthora, Phytopythium and Pythium were found, Phytopythium vexans and Phytophthora niederhauserii being the most frequent. The pathogenicity of these two species to one-year-old almond seedlings of ‘Garnem’ (P. dulcis × P. persica) rootstock was studied. All seedlings inoculated with Pp. vexans and Ph. niederhauserii isolates showed severe symptoms at the late stage of the pathogenicity test (defoliation, wilting and dieback) and several plants died. Some isolates of Ph. niederhauserii significantly reduced the dry weight of the roots compared with the control, but this effect was not observed in seedlings inoculated with Pp. vexans. These results provide new information about the oomycete species present in almond crops in Spain and highlight the importance of carrying out frequent phytosanitary surveys for a better knowledge of potential risks posed by these soil-borne pathogens.

Patterns and roles of lignan and terpenoid accumulation in the reaction zone compartmentalizing pathogen-infected heartwood of Norway spruce

Main conclusionLignan impregnation of the reaction zone wood protects against oxidative degradation by fungi. Traumatic resin canals may play roles in the underlying signal transduction, synthesis, and translocation of defense compounds.Tree defense against xylem pathogens involves both constitutive and induced phenylpropanoids and terpenoids. The induced defenses include compartmentalization of compromised wood with a reaction zone (RZ) characterized by polyphenol deposition, whereas the role of terpenoids has remained poorly understood. To further elucidate the tree–pathogen interaction, we profiled spatial patterns in lignan (low-molecular-weight polyphenols) and terpenoid content in Norway spruce (Picea abies) trees showing heartwood colonization by the pathogenic white-rot fungus Heterobasidion parviporum. There was pronounced variation in the amount and composition of lignans between different xylem tissue zones of diseased and healthy trees. Intact RZ at basal stem regions, where colonization is the oldest, showed the highest level and diversity of these compounds. The antioxidant properties of lignans obviously hinder oxidative degradation of wood: RZ with lignans removed by extraction showed significantly higher mass loss than unextracted RZ when subjected to Fenton degradation. The reduced diversity and amount of lignans in pathogen-compromised RZ and decaying heartwood in comparison to intact RZ and healthy heartwood suggest that α-conindendrin isomer is an intermediate metabolite in lignan decomposition by H. parviporum. Diterpenes and diterpene alcohols constituted above 90% of the terpenes detected in sapwood of healthy and diseased trees. A significant finding was that traumatic resin canals, predominated by monoterpenes, were commonly associated with RZ. The findings clarify the roles and fate of lignan during wood decay and raise questions about the potential roles of terpenoids in signal transduction, synthesis, and translocation of defense compounds upon wood compartmentalization against decay fungi.

Citrus Stubborn Disease: Current Insights on an Enigmatic Problem Prevailing in Citrus Orchards.

Citrus stubborn was initially observed in California in 1915 and was later proven as a graft-transmissible disease in 1942. In the field, diseased citrus trees have compressed and stunted appearances, and yield poor-quality fruits with little market value. The disease is caused by Spiroplasma citri, a phloem-restricted pathogenic mollicute, which belongs to the Spiroplasmataceae family (Mollicutes). S. citri has the largest genome of any Mollicutes investigated, with a genome size of roughly 1780 Kbp. It is a helical, motile mollicute that lacks a cell wall and peptidoglycan. Several quick and sensitive molecular-based and immuno-enzymatic pathogen detection technologies are available. Infected weeds are the primary source of transmission to citrus, with only a minor percentage of transmission from infected citrus to citrus. Several phloem-feeding leafhopper species (Cicadellidae, Hemiptera) support the natural spread of S. citri in a persistent, propagative manner. S. citri-free buds are used in new orchard plantings and bud certification, and indexing initiatives have been launched. Further, a quarantine system for newly introduced types has been implemented to limit citrus stubborn disease (CSD). The present state of knowledge about CSD around the world is summarized in this overview, where recent advances in S. citri detection, characterization, control and eradication were highlighted to prevent or limit disease spread through the adoption of best practices.

Identification of a new Hazelnut disease in Liaoning Province: Hazelnut husk brown rot

Hazelnut husk brown rot has been identified as a new disease in Liaoning Province in recent years. The objective of this study as to identify the pathogen. [Method] In this study, a standard sample of hazelnut husk brown rot was collected from Songmudao Base in Dalian City, Liaoning Province. The pathogen was identified by the studies of the morphology, pathogenicity, and analyses of ITS and LSU sequences. The pathogen was isolated and purified, which was confirmed by Koch’s postulates. The symptoms after inoculation were the same as those collected directly from a diseased tree, which showed that it was the pathogenic fungus. The cultural characteristics and conidia and the morphology of the pathogenic fungi were similar to those of Botrytis cinerea’s. The ITS sequences and LSU sequences were compared to the associated strain sequences in GenBank, with 100% identity to Botrytis cinerea (GenBank accession number: MN589848.1) and Botrytis cinerea (GenBank accession number: KU140653.1), respectively. The infection status of the pathogen on the hazelnut husks was also observed. The studies suggested that the pathogen leading to the hazelnut husk brown rot as a new disease in Liaoning Province was Botrytis cinerea.

The role of agriculture in human infectious disease outbreaks

AbstractThis study uses the available data to explore the temporal and geographical patterns of infectious diseases and their links between human demography, human-induced land-use change, livestock and poultry expansion, and biodiversity loss. Over the last decades, the number of outbreaks of zoonotic and vector-borne diseases increased mostly in the intertropical zone. The increase in cropland, grassland, tree plantation, livestock, poultry, biodiversity at threat (using the Red List index) mostly occurred in the intertropical zone. Using structural equation modeling, significant relationships were observed between disease outbreaks, human demography, livestock (cattle and pigs), poultry (chickens), tree plantation and artificial land expansion as well as with increasing biodiversity at threat. While agricultural expansion is seen as a driver of biodiversity loss and potentially emerging infectious diseases, here we show that cropland and grassland expansion does not appear to enhance disease outbreaks directly, but indirectly and only for cropland on biodiversity loss. The links observed between infectious disease outbreaks, human demography, agriculture, livestock, urbanization and biodiversity should help rethink the global food system in ways that minimize the risk of infectious diseases while preserving biodiversity and contributing to Sustainable Goals.

Nondestructive Inspection of Tree Trunks Using a Dual-Polarized Ground-Penetrating Radar System

In recent years, trees in European countries have been increasingly endangered by emerging infectious diseases (EIDs). In the United Kingdom, this has been observed to affect whole woodlands and forests, threatening the existence of some types of trees. Although quarantine measures have been taken to limit the spreading of such diseases, this has not yet been effectively controlled leading to millions of trees affected by EIDs. Ground-penetrating radar (GPR) has proven effective in identifying critical features on diseased trees for detection of EIDs spread. However, the irregular shape of tree trunks and their complex internal structure represent real challenges for conventional GPR measurements and data processing methodologies. In this research, a dual-polarised GPR system is used to detect internal decay in tree trunks using novel signal processing methodologies. A polarimetric correlation filter based on Bragg Scattering on a 3D Pauli feature vector and an arc-shaped Kirchhoff migration are discussed in detail. The proposed polarimetric correlation filter is utilised to enhance the signal-to-noise ratio (SNR) of B-scans due to bark and tree trunk high-loss properties of tree trunks. Meanwhile, an arc-shaped Kirchhoff migration algorithm is performed to counteract the influence of the bark irregularity. The proposed data processing framework is successfully validated with measurements on a real tree trunk, where cross-sections were subsequently cut for comparison purposes. Outcomes from the proposed methodology demonstrate a high consistency with the features observed on the tree trunk cross-sections, indicating the reliability of the proposed detection scheme for assessing tree-decay associated with EIDs.

Tree mortality caused by Diplodia shoot blight on Pinus sylvestris and other mediterranean pines

Diplodia shoot blight is an emergent forest disease in Europe caused by Diplodia sapinea. The short-term impacts of the pathogen on tree physiology are well known, but its capacity to cause mortality has been poorly documented.We compared the survival of four pine species affected by Diplodia shoot blight following a hailstorm: Pinus sylvestris, P. nigra, P. pinea and P. halepensis. In the case of P. sylvestris, survival in the hail-affected sites was compared with survival in other sites affected by Diplodia shoot blight with no hailstorm records. Mortality and crown condition were recorded over two years. Dendrochronological analyses were conducted to assess growth responses to drought and to test the influence of radial growth before the outbreak of Diplodia shoot blight on survival. The endophytic community, as well as the abundance of D. sapinea, was quantified by metabarcoding and qPCR respectively, and were correlated with crown damage.Crown damage was the best predictor of mortality across species. Pinus sylvestris experienced a much higher rate of mortality than P. nigra, P. pinea and P. halepensis. Two years after the outbreak, P. halepensis was the only species that could recover crown condition. Mortality was found to be unrelated to radial growth prior the outbreak. Drought responses did not correlate with mortality differences across pine species or sites. In the case of P. sylvestris, mortality was initially higher amongst diseased trees in areas affected by hailstorms than in sites not affected by hailstorms, however it tended to equalise after two years. Amongst P. sylvestris trees, crown damage correlated with a higher abundance of the pathogen. Signs of competition amongst endophytes were observed between non-defoliated and defoliated Scots pine trees following hailstorms.Our study shows that D. sapinea can cause a significant mortality to P. sylvestris. The legacy effects of crown damage can last for at least two years after an outbreak. During this time, crown damage is a good predictor of survival, and can help managers decide which trees remove after an outbreak.

Survey, Identification, and Pathogenicity of Ceratocystis fimbriata Complex Associated with Wilt Disease on Acacia mangium in Malaysia

Ceratocystis wilt disease surveys were conducted in three selected Malaysian Acacia mangium plantations. These completed surveys revealed the occurrence of the wilt disease, with the incidence of infection ranging from 7.5% to 13.6%. Signs of wood-boring insects, bark peeling due to squirrel activity, and pruning wounds were often associated with this disease. The fungus most frequently isolated from the diseased trees was the Ceratocystis fungus. The analysis on the morphological characteristics has identified the fungus as Ceratocystis fimbriata complex. Phylogenetic analysis based on the sequences of the ITS, and concatenated sequences of EF1α-βT regions grouped the isolates within the C. fimbriata sensu stricto, in comparison to other C. fimbriata isolates. Pathogenicity tests were conducted on six to nine-month-old healthy A. mangium seedlings by inoculating these seedlings with eight out of the 16 isolates. The results demonstrated that all the isolates were pathogenic, with mortality beginning as early as two weeks after inoculation. However, an ANOVA test indicated a significant difference between the pathogenicity levels among the fungal isolates. The results also showed that pathogen aggressiveness was not correlated with geographical origin. A host range test was also conducted by using C. fimbriata SSB3 and FRIM1162 isolates against several forest plantation species. The findings suggested that only A. mangium was susceptible to C. fimbriata. The other species remained healthy with no symptoms of infection even after seven weeks of treatment, as compared to the A. mangium species, where between 38 to 60% of the inoculated plants had died. This study provides new information on the status of Ceratocystis wilt disease, especially on the occurrence and effects on A. mangium plantation, by giving insights on how to control and manage this ferocious plant pathogen in the future.