Molecular and Pathogenic Characteristics of Paecilomyces formosus, a New Causal Agent of Oak Tree Dieback in Iran

2019 ◽  
Vol 65 (6) ◽  
pp. 743-750 ◽  
Author(s):  
Mohammad Sabernasab ◽  
Samad Jamali ◽  
Alireza Marefat ◽  
Saeed Abbasi
Keyword(s):  
Causal Agent ◽  
Thermophilic Fungi ◽  
Oak Trees ◽  
Tree Dieback ◽  
Pathogenicity Tests ◽  
Oak Tree ◽  
Pathogen Recovery ◽  
Branch Dieback ◽  
Internal Transcribed Spacer Rdna

Abstract Oak dieback is one of the most important diseases that presently affects the Kermanshah oak forests (West Iran). During the period from 2013 to 2015, oak trees exhibiting branch dieback were sampled, and fungal colonies resembling those of the Paecilomyces sp. were obtained from diseased tissues. Based on morphology, physiology, and phylogeny of the internal transcribed spacer rDNA, all isolates were identified as Paecilomyces formosus. Pathogenicity tests in vivo were made on 2-year-old seedlings, potted Q. brantii plants, and excised branch sections under controlled conditions. Inoculated seedlings produced characteristic symptoms, and subsequent pathogen recovery confirmed pathogenicity. We determined these to be thermophilic fungi, which may be related to warming and drought. This is the first report of Paecilomyces formosus as the causal agent of Q. brantii dieback in Iran and the world.

scholarly journals Investigation of oak tree decline in the Auckland region

2007 ◽  
Vol 60 ◽  
pp. 297-303
Author(s):  
M. Braithwaite ◽  
C. Inglis ◽  
M.A. Dick ◽  
T.D. Ramsfield ◽  
N.W. Waipara ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Molecular Techniques ◽  
Tree Decline ◽  
New Host ◽  
Disease Symptoms ◽  
Oak Trees ◽  
Oak Tree ◽  
Intensive Investigation ◽  
Biochemical Testing ◽  
Branch Dieback

Concern about the poor health of oak trees in Auckland was raised in 2001 An intensive investigation of oak trees showing symptoms of decline (twig and branch dieback epicormic growth trunk cankers bark loss and tree death) was conducted in the Auckland area during 2006 Disease symptoms on trees at 13 sites were documented and samples of leaves stems trunks roots and soil collected Soil samples were tested for the presence of soilborne fungi using baiting techniques Fungi and bacteria from plant tissues and soil were identified using either morphological characteristics biochemical testing or molecular techniques The investigation resulted in a range of fungi and bacteria being identified One fungus new to New Zealand was detected and several new host associations observed No particular organism was implicated as the cause of the oak decline but several fungi and bacteria were likely contributors to the tree decline and death in Auckland

scholarly journals Cork Oak Endophytic Fungi as Potential Biocontrol Agents against Biscogniauxia mediterranea and Diplodia corticola

2020 ◽  
Vol 6 (4) ◽  
pp. 287
Author(s):  
Daniela Costa ◽  
Rui M. Tavares ◽  
Paula Baptista ◽  
Teresa Lino-Neto
Keyword(s):  
Fungal Endophytes ◽  
Cork Oak ◽  
In Vivo Assays ◽  
Oak Trees ◽  
Treatment Measures ◽  
Dual Plate ◽  
Antagonistic Potential ◽  
Selection Of

An increase in cork oak diseases caused by Biscogniauxia mediterranea and Diplodia corticola has been reported in the last decade. Due to the high socio-economic and ecologic importance of this plant species in the Mediterranean Basin, the search for preventive or treatment measures to control these diseases is an urgent need. Fungal endophytes were recovered from cork oak trees with different disease severity levels, using culture-dependent methods. The results showed a higher number of potential pathogens than beneficial fungi such as cork oak endophytes, even in healthy plants. The antagonist potential of a selection of eight cork oak fungal endophytes was tested against B. mediterranea and D. corticola by dual-plate assays. The tested endophytes were more efficient in inhibiting D. corticola than B. mediterranea growth, but Simplicillium aogashimaense, Fimetariella rabenhorstii, Chaetomium sp. and Alternaria alternata revealed a high potential to inhibit the growth of both. Simplicillium aogashimaense caused macroscopic and microscopic mycelial/hyphal deformations and presented promising results in controlling both phytopathogens’ growth in vitro. The evaluation of the antagonistic potential of non-volatile and volatile compounds also revealed that A. alternata compounds could be further explored for inhibiting both pathogens. These findings provide valuable knowledge that can be further explored in in vivo assays to find a suitable biocontrol agent for these cork oak diseases.

scholarly journals Coccinonectria pachysandricola, Causal Agent of a New Foliar Blight Disease of Sarcococca hookeriana

Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1337-1346 ◽  
Author(s):  
Catalina Salgado-Salazar ◽  
Nina Shiskoff ◽  
Nicholas LeBlanc ◽  
Adnan A. Ismaiel ◽  
Maxton Collins ◽  
...  
Keyword(s):  
Woody Plants ◽  
Causal Agent ◽  
Washington Dc ◽  
Disease Symptoms ◽  
Foliar Blight ◽  
Pathogenicity Tests ◽  
Artificial Inoculations ◽  
Blight Disease ◽  
Genome Assemblies ◽  
Severe Leaf

Woody plants of the Buxaceae, including species of Buxus, Pachysandra, and Sarcococca, are widely grown evergreen shrubs and groundcovers. Severe leaf spot symptoms were observed on S. hookeriana at the U.S. National Arboretum in Washington, DC, in 2016. Affected plants were growing adjacent to P. terminalis exhibiting Volutella blight symptoms. Fungi isolated from both hosts were identical based on morphology and multilocus phylogenetic analysis and were identified as Coccinonectria pachysandricola (Nectriaceae, Hypocreales), causal agent of Volutella blight of Pachysandra species. Pathogenicity tests established that Co. pachysandricola isolated from both hosts caused disease symptoms on P. terminalis and S. hookeriana, but not on B. sempervirens. Artificial inoculations with Pseudonectria foliicola, causal agent of Volutella blight of B. sempervirens, did not result in disease on P. terminalis or S. hookeriana. Wounding enhanced infection by Co. pachysandricola and Ps. foliicola on all hosts tested but was not required for disease development. Genome assemblies were generated for the Buxaceae pathogens that cause Volutella diseases: Co. pachysandricola, Ps. buxi, and Ps. foliicola; these ranged in size from 25.7 to 28.5 Mb. To our knowledge, this foliar blight of S. hookeriana represents a new disease for this host and is capable of causing considerable damage to infected plants.

scholarly journals Neofusicoccum mediterraneum Is Involved in a Twig and Branch Dieback of Olive Trees Observed in Salento (Apulia, Italy)

Pathogens ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 53
Author(s):  
Angela Brunetti ◽  
Antonio Matere ◽  
Valentina Lumia ◽  
Vittorio Pasciuta ◽  
Valeria Fusco ◽  
...  
Keyword(s):  
Prolonged Exposure ◽  
Fungal Species ◽  
In Vitro Tests ◽  
Wood Discoloration ◽  
Olive Groves ◽  
Pathogenicity Tests ◽  
Olive Quick Decline Syndrome ◽  
Olive Trees ◽  
Branch Dieback

Olive trees are infected and damaged by Botryosphaeriaceae fungi in various countries. The botryosphaeriaceous fungus Neofusicoccum mediterraneum is highly aggressive and is a major concern for olive groves in Spain and California (USA), where it causes ‘branch and twig dieback’ characterized by wood discoloration, bark canker, and canopy blight. During surveys of olive groves in Apulia (southern Italy), we noticed that—in some areas—trees were heavily affected by severe branch and twig dieback. In addition, chlorosis and the appearance of red-bronze patches on the leaf preceded the wilting of the foliage, with necrotic leaves persisting on the twigs. Given the severity of the manifestation in zones also subject to olive quick decline syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca, we investigated the etiology and provide indications for differentiating the symptoms from OQDS. Isolation from diseased wood samples revealed a mycete, which was morphologically and molecularly identified as N. mediterraneum. The pathogenicity tests clearly showed that this fungus is able to cause the natural symptoms. Therefore, also considering the low number of tested samples, N. mediterraneum is a potential causal agent of the observed disease. Specifically, inoculation of the twigs caused complete wilting in two to three weeks, while inoculation at the base of the stem caused severe girdling wedge-shaped cankers. The growth rate of the fungus in in vitro tests was progressively higher from 10 to 30 °C, failing to grow at higher temperatures, but keeping its viability even after prolonged exposure at 50 °C. The capacity of the isolate to produce catenulate chlamydospores, which is novel for the species, highlights the possibility of a new morphological strain within N. mediterraneum. Further investigations are ongoing to verify whether additional fungal species are involved in this symptomatology.

Are wild insectivorous birds attracted to methyl-jasmonate-treated Pyrenean oak trees?

Behaviour ◽  
2018 ◽  
Vol 155 (13-15) ◽  
pp. 945-967 ◽  
Author(s):  
Irene Saavedra ◽  
Luisa Amo
Keyword(s):  
Jasmonic Acid ◽  
Methyl Jasmonate ◽  
Field Experiments ◽  
Predation Rate ◽  
Signalling Pathway ◽  
Insectivorous Birds ◽  
Oak Trees ◽  
Prey Location ◽  
Oak Tree ◽  
Herbivore Induced Plant Volatiles

Abstract Plants emit herbivore-induced plant volatiles (HIPVs) when they are attacked by herbivorous arthropods to attract natural enemies of the herbivores. Previous studies have suggested that insectivorous birds can detect the HIPVs for prey location. The production of HIPVs is partly mediated by the jasmonic acid signalling pathway. Methyl jasmonate is one compound involved in the jasmonic acid signalling pathway. Therefore, spraying of methyl jasmonate (MeJa) solution on plants can induce the emission of volatiles similar to the HIPVs induced by herbivory. We performed two field experiments to test whether insectivorous adult birds are attracted to Pyrenean oak trees (Quercus pyrenaica) treated with MeJa solutions. We used artificial larvae to measure bird predation rate. There were no differences in the predation rates of plasticine larvae between control and MeJa treatments, suggesting that insectivorous birds were not attracted to trees treated with MeJa. We also tested whether blue tit nestlings without previous experience in foraging respond to the scent of Pyrenean oak tree leaves treated with MeJa, to test whether the attraction to MeJa-treated trees is innate. A similar number of nestlings performed begging responses when exposed to the scent of leaves of MeJa-treated trees compared to the scent of leaves of control untreated trees. Furthermore, the duration of the first begging was similar in response to the volatiles emitted by MeJa-treated trees and untreated trees. Despite previous evidence suggesting that insectivorous birds are attracted to HIPVs, our results show that neither insectivorous adult birds nor inexperienced nestlings were attracted to trees treated with MeJa. Further studies are needed to disentangle whether the differences in the emission of volatiles between herbivore-infested trees and MeJa-treated trees can explain this lack of attraction to MeJa-treated Pyrenean oak trees.

Vascular Fungi Associated with Branch Dieback of Olive in Super-High-Density Systems in Southern Spain

Plant Disease ◽  
2020 ◽  
Author(s):  
Carlos Agustí-Brisach ◽  
José Pablo Jiménez-Urbano ◽  
Maria Carmen Raya-Ortega ◽  
Ana López-Moral ◽  
Antonio Trapero-Casas
Keyword(s):  
Mycelial Growth ◽  
Culture Media ◽  
High Density ◽  
Southern Spain ◽  
Effect Of Temperature ◽  
Phaeomoniella Chlamydospora ◽  
Potted Plants ◽  
Pathogenicity Tests ◽  
Colony Color ◽  
Branch Dieback

Symptoms of branch dieback of olive with internal longitudinal dark streaking were observed during routine surveys in super high-density systems in southern Spain. Nineteen fungal isolates recovered from wood samples showing internal discoloration and necrotic xylem vessels were selected. Multilocus alignments of ITS, LSU, TUB and/or ACT were performed, and the following species were identified: Acremonium sclerotigenum, Cadophora luteo-olivacea, Paracremonium sp., Phaeoacremonium italicum, Ph. minimum, Ph. scolyti and Pseudophaeomoniella oleicola. Colony color, mycelial growth, conidial characteristics and production were defined on PDA, MEA and OA. Phenotypic characteristics and conidial production varied depending on the isolate and culture media. The effect of temperature on mycelial growth was evaluated on MEA. The isolates showed slowly mycelial growth (0.5-2.0 mm day-1), with the optimum temperature ranging from 23.2 to 33.9 °C. Pathogenicity tests were conducted on nine-month-old olive potted plants (‘Arbequina’) inoculated with mycelial plugs. Cadophora luteo-olivacea, Pm. minimum and Phaeomoniella chlamydospora isolates from grapevine were included in the pathogenicity tests for comparative purposes. Prior to inoculation, the effect on the infection by inoculating with conidial suspensions or mycelial plugs was evaluated, with the second method being the most effective. Cadophora luteo-olivacea was the most aggressive fungi to olive followed by Pm. minimum.

scholarly journals Identification of the causal agent of “pata seca” in pepper crop production areas of Ecuador

2018 ◽  
Vol 44 (4) ◽  
pp. 338-343
Author(s):  
Miguel Angel Quilambaqui Jara ◽  
Antonio Carlos Maringoni
Keyword(s):  
Capsicum Annuum ◽  
Crop Production ◽  
Sclerotium Rolfsii ◽  
Causal Agent ◽  
Economic Losses ◽  
Fusarium Spp ◽  
Pathogenicity Tests ◽  
Production Areas ◽  
Disease Analysis ◽  
Santa Elena

ABSTRACT Cultivation of pepper (Capsicum annuum L.) has high economic relevance in Ecuador. Although the planted area is approximately 5704 ha, its productivity is low (3.17 t ha-1) relative to other countries in the region. In recent years, the spread and the development of a disease that leads the plant to death, known by farmers as “pata seca” and occurring in production zones located in Guayas and Santa Elena Provinces, have caused great economic losses. The aim of this study was to evaluate the effect of “pata seca” on commercial pepper crops during 2013 and 2014 and to identify the causal agent of such disease. Twenty-three farms were visited, where samples and data were collected. “Pata seca” was detected in 79.2% samples, and 53.6% plants had symptoms of this disease. Analysis of the samples collected in 2013 and 2014 indicated that the predominant fungi were Sclerotium rolfsii (31.17%, 49.64%) and Fusarium spp. (29.29%, 32.37%), respectively. Pathogenicity tests confirmed that S. rofsii is the major causal agent.

Variations and correlations within and between morphology, pathogenicity, and pectolytic enzyme activity in Sclerotinia from Saskatchewan

1972 ◽  
Vol 50 (4) ◽  
pp. 767-786 ◽  
Author(s):  
R. A. A. Morrall ◽  
L. J. Duczek ◽  
J. W. Sheard
Keyword(s):  
Host Species ◽  
Enzyme Activities ◽  
Pectin Methylesterase ◽  
Defined Medium ◽  
Discrete Groups ◽  
Pectolytic Enzymes ◽  
Pathogenicity Tests ◽  
Pectolytic Enzyme

One hundred and fourteen isolates of Sclerotinia from 23 different hosts in many parts of Saskatchewan were grouped, according to their morphology, on minimal medium. Two types of seedling pathogenicity tests on six host species were conducted on at least one isolate from each morphological group and one from each host species. A total of 38 isolates was tested. Assays for pectolytic enzyme activities of the same 38 isolates were done using a defined medium, and Swede turnip and carrot tissue as substrates. Polygalacturonase, pectin transeliminase, and pectin methylesterase were all tested. The results showed that an endopolygalacturonase was probably the most prevalent enzyme. Some isolates also produced exopolygalacturonase and pectin methylesterase, but pectin transeliminase was never detected. There was no correlation between pathogenicity of the isolates and their enzyme activities in vitro or in vivo, suggesting that pectolytic enzymes are not responsible alone for pathogenicity. Agglomerative classification was used to demonstrate relationships between the isolates. However, the isolates did not fall into discrete groups based on morphological, pathological, physiological, or even combined characteristics. Neither were there clear host or geographic associations. This continuous variation rather than a segregated population is consistent with Purdy's "broader concept of the species S. sclerotiorum."

scholarly journals Identification of Fungal Species Associated with Branch Dieback of Olive and Resistance of Table Cultivars to Neofusicoccum mediterraneum and Botryosphaeria dothidea

Plant Disease ◽  
2017 ◽  
Vol 101 (2) ◽  
pp. 306-316 ◽  
Author(s):  
Juan Moral ◽  
Carlos Agustí-Brisach ◽  
Mario Pérez-Rodríguez ◽  
Carlos Xaviér ◽  
M. Carmen Raya ◽  
...  
Keyword(s):  
Dna Analysis ◽  
Large Subunit ◽  
Fungal Species ◽  
Control Measures ◽  
Nuclear Ribosomal Dna ◽  
Botryosphaeria Dothidea ◽  
Immature Fruit ◽  
Pathogenicity Tests ◽  
Olive Trees ◽  
Branch Dieback

Over two consecutive seasons, 16 olive orchards with trees exhibiting dieback symptoms on branches were surveyed in southern Spain. The six dominant fungal species recovered were characterized by means of phenotypic observations, DNA analysis (by sequencing of the internal transcribed spacer, β-tubulin, and large subunit nuclear ribosomal DNA regions), and pathogenicity tests. Additionally, three isolates collected from Tunisian olive trees showing similar dieback symptoms, one isolate of Colletotrichum godetiae, and a reference isolates of Neofusicoccum mediterraneum were included. The resistance of the 11 most important table cultivars to N. mediterraneum and Botryosphaeria dothidea, the causal agent of “escudete” (small shield) of fruit, was studied by the inoculation of branches and immature fruit, respectively. The species Cytospora pruinosa, N. mediterraneum, Nothophoma quercina, Comoclathris incompta, and Diaporthe sp. were identified. Only N. mediterraneum and C. incompta were able to induce the typical dieback symptoms and cankers that affected the development of the plants. The species N. mediterraneum was the most virulent among the evaluated species, although differences in virulence among its isolates were observed. The remaining fungal species were weakly pathogenic to nonpathogenic on plants. According to resistance tests, ‘Gordal Sevillana’ and ‘Manzanilla Cacereña’ were the most susceptible to branch dieback caused by N. mediterraneum. Furthermore, the fruit of ‘Aloreña de Atarfe’ and ‘Manzanilla de Sevilla’ were the most susceptible to B. dothidea. Knowledge of the etiology and cultivar resistance of these diseases will help to establish better control measures.

scholarly journals A Date Palm Disease (Bunch Blight) Caused by Acremonium strictum (Cephalosporium) in Saudi Arabia

2018 ◽  
Vol 7 (1) ◽  
pp. 01-06
Author(s):  
Mohammad F. Rashed
Keyword(s):  
Saudi Arabia ◽  
Dna Sequence ◽  
Date Palm ◽  
Early Stage ◽  
Causal Agent ◽  
Acremonium Strictum ◽  
Pathogenicity Tests

Acrimonium strictum is reported as a new causal agent of a disease it names (bunch blight) in date palm (phoenix dactylefera) in Saudi Arabia. Symptoms and necrosis caused by A. strictum in susceptible cultivars showed small brown necrosis streak at midrib of fruit stalk in an early stage. There was an increase in number and size as the disease progresses; then extended to the bases of fruit strands due to death of bases and strands wilt, the infection of fruit strand caused drying the fruits and their fall. A. strictum attacks the bunches and move quickly inside and out the tissues causing brown necrosis and death of the tissues. A. strictum was isolated and pathogenicity tests were repeated more than once during two seasons and the identifications was caried several ways to confirm The confirmation of results by Biolog technique and DNA sequence were done. The proper temperature for infection was between 20-30 °C and the optimum 25 °C. When testing the susceptibility of varieties of infection, more varieties like Medjool, Saqae and Kholas were susceptible to infection and the most resistant to infection were Barhy and Khidri. The best results in the control of the fungus in vitro were due to use of Karpendazem followed Topsen M70, at the same time, the worst results were seen with the use of Abredion followed Karant (Cupper hydroxide).

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