scholarly journals Fusarium spp., Cylindrocarpon spp., and Environmental Stress in the Etiology of a Canker Disease of Cold-Stored Fruit and Nut Tree Seedlings in California

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 259-270 ◽  
Author(s):  
Stephen M. Marek ◽  
Mohammad A. Yaghmour ◽  
Richard M. Bostock
Keyword(s):  
Cold Storage ◽  
Signs And Symptoms ◽  
Tissue Loss ◽  
Tree Seedlings ◽  
Canker Disease ◽  
Almond Trees ◽  
Asymptomatic Infections ◽  
Canker Development ◽  
Stem Segments ◽  
Increased Susceptibility

The principal objective of this study was to determine the etiology of a canker disease in dormant stone fruit and apple tree seedlings maintained in refrigerated storage that has significantly impacted California fruit and nut tree nurseries. Signs and symptoms of the disease develop during storage or soon after planting, with subsequent decline and death of young trees. Isolations from both diseased and healthy almond and apple trees and Koch's postulates using stem segments of desiccation-stressed almond trees as hosts implicated Fusarium avenaceum and F. acuminatum as the primary causal agents. F. solani, Ilyonectria robusta, and Cylindrocarpon obtusiusculum were also capable of causing similar symptoms but were less frequently encountered in isolations of diseased tissue. Loss of bark turgidity in excised almond stem segments, as can occur in cold-stored seedlings, correlated with increased susceptibility to F. acuminatum, with maximum canker development occurring after relative bark turgidity dropped below a threshold of approximately 86%. Healthy almond trees, almond scion budwood, and a wheat cover crop used in fields where tree seedlings were grown and maintained until cold storage all possessed asymptomatic infections of F. acuminatum, F. avenaceum, and C. obtusiusculum as determined by activation following overnight freezing, cold storage, or desiccation.

Genetic diversity and potential inoculum sources of Fusarium species causing cankers in bareroot-propagated almond trees in California nurseries

Plant Disease ◽  
2021 ◽  
Author(s):  
Abigail Justine Stack ◽  
Stephen Mark Marek ◽  
Thomas Gordon ◽  
Richard M. Bostock
Keyword(s):  
Cold Storage ◽  
Fusarium Species ◽  
Storage Facility ◽  
Clonal Lineage ◽  
Fusarium Spp ◽  
Inoculum Sources ◽  
Canker Disease ◽  
Fusarium Acuminatum ◽  
Almond Trees ◽  
Rotation Crops

Previous research determined that Fusarium acuminatum and Fusarium avenaceum are important causal agents of a canker disease in bareroot-propagated fruit and nut trees in California that emerges during cold-storage or after transplanting. The disease largely disappeared after 2001, but it reemerged in 2011 in almond trees in at least one nursery. This motivated further study of the etiology and epidemiology of the disease by undertaking studies to determine distribution of the pathogens throughout almond nursery propagation systems and trace possible sources of inoculum. Research initiated in 2013 detected pathogenic Fusarium spp. throughout the almond propagation system, including in healthy trees, in soils, on wheat rotation crops, on equipment, and in the cold storage facility air. In addition to the two Fusarium spp. implicated previously, Fusarium brachygibbosum and a new Fusarium species, Fusarium californicum, were found to be pathogenic on almond trees. Multi-locus sequence typing and somatic compatibility testing confirmed that isolates within a species collected from different materials in the nursery were all highly genetically similar and likely of one clonal lineage. These findings affirm that equipment surfaces, wheat rotation crops, soil, cold storage facility air, and asymptomatic almond tree materials (i.e., rootstock cuttings, budwood, and scions) can potentially contribute inoculum to increase disease prevalence and severity.

scholarly journals Seasonal Variation in Host Susceptibility to Fusarium Canker in Young Almond Trees

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 772-779
Author(s):  
Abigail J. Stack ◽  
Meera Madra ◽  
Thomas R. Gordon ◽  
Richard M. Bostock
Keyword(s):  
Cold Storage ◽  
Fusarium Species ◽  
Lesion Size ◽  
Host Susceptibility ◽  
Seasonal Effect ◽  
Canker Disease ◽  
Almond Trees ◽  
Bare Root ◽  
The Impact

Loss of water that reduces the relative water content (RWC) of bark can occur during processing, cold storage, and planting of bare-root stone fruit trees. In California nurseries and newly planted orchards, this stress can predispose young almond trees (Prunus dulcis) to a canker disease caused primarily by Fusarium species. While reduced bark RWC contributes to disease development, anecdotal observations suggest a seasonal effect on host physiology may also influence disease severity. We evaluated the effect of season and the impact of drying and reduced RWC on susceptibility of almond branch segments excised from orchard trees (cv. Nonpareil) to Fusarium acuminatum, Fusarium avenaceum, Fusarium brachygibbosum, and Fusarium californicum sp. nov. With lesion size as the criterion, excised inoculated branch segments were most susceptible in spring, of intermediate susceptibility during winter dormancy, and least susceptible during summer and fall. Consistent with an earlier study, branches with RWC between 80 and 85% yielded lesions that were significantly larger than lesions from branches with bark that was above or below that range. However, the effect of reduced bark moisture on lesion size was only apparent in the spring. These results affirm the importance of avoiding conditions that diminish moisture status in bare-root almond trees in Fusarium canker disease management, especially during transport and planting operations in the spring, a period of high physiological vulnerability. California nurseries apply fungicides to bare-root trees prior to cold storage to reduce “mold” growth. Of eight fungicides currently registered for use on almond trees, fludioxonil (Scholar), fluopyram/trifloxystrobin (Luna Sensation), and fluxapyroxad/pyraclostrobin (Merivon) were most inhibitory to in vitro mycelial growth of F. acuminatum, F. avenaceum, and F. brachygibbosum. However, our almond branch disease assay did not demonstrate preventive or curative fungicide action against infections by F. acuminatum or F. avenaceum.

scholarly journals Systematic Analysis and Functional Validation of Citrus Pectin Acetylesterases (CsPAEs) Reveals that CsPAE2 Negatively Regulates Citrus Bacterial Canker Development

2020 ◽  
Vol 21 (24) ◽  
pp. 9429
Author(s):  
Qiang Li ◽  
Jia Fu ◽  
Xiujuan Qin ◽  
Wen Yang ◽  
Jingjing Qi ◽  
...  
Keyword(s):  
Susceptible Variety ◽  
Resistant Variety ◽  
Potential Candidate ◽  
Bacterial Canker ◽  
Citrus Pectin ◽  
Systematic Analysis ◽  
Canker Disease ◽  
Potential Candidate Gene ◽  
Citrus Bacterial Canker ◽  
Canker Development

The present study was designed to serve as a comprehensive analysis of Citrus sinensis (C. sinensis) pectin acetylesterases (CsPAEs), and to assess the roles of these PAEs involved in the development of citrus bacterial canker (CBC) caused by Xanthomonas citri subsp. citri (Xcc) infection. A total of six CsPAEs were identified in the genome of C. sinensis, with these genes being unevenly distributed across chromosomes 3, 6, and 9, and the unassembled scaffolds. A subset of CsPAEs were found to be involved in responses to Xcc infection. In particular, CsPAE2 was identified to be associated with such infections, as it was upregulated in CBC-susceptible variety Wanjincheng and inversely in CBC-resistant variety Calamondin. Transgenic citrus plants overexpressing CsPAE2 were found to be more susceptible to CBC, whereas the silencing of this gene was sufficient to confer CBC resistance. Together, these findings provide evolutionary insights into and functional information about the CsPAE family. This study also suggests that CsPAE2 is a potential candidate gene that negatively contributes to bacterial canker disease and can be used to breed CBC-resistant citrus plants.

scholarly journals Cold Storage Method Affects Root and Shoot Water Potential of Bare-root Hawthorn and Maple Trees

1994 ◽  
Vol 12 (4) ◽  
pp. 219-222
Author(s):  
Rick M. Bates ◽  
Alexander X. Niemiera ◽  
John R. Seiler
Keyword(s):  
Cold Storage ◽  
Water Loss ◽  
Poor Quality ◽  
Tree Seedlings ◽  
Water Potentials ◽  
Whole Plant ◽  
Norway Maple ◽  
Root Stock ◽  
Bare Root ◽  
Root Tree

Abstract Desiccation of bare-root tree seedlings during storage can result in reduced growth and poor quality after transplanting. For 12 weeks, shoot and root water potentials of bare-root Norway maple (Acer platanoides L.) and Washington hawthorn (Crataegus phaenopyrum Medic.) seedlings were measured in response to four cold storage treatments: whole plant exposed, roots exposed, shoots exposed, whole plant covered. In another experiment, water loss was measured from stem sections of both species during four weeks of cold storage. Shoot and root water potentials decreased during storage regardless of treatment or species. For maple, shoot and root water potentials of the exposed shoot treatment were the same as the whole plant covered treatment. In contrast, hawthorn shoot and root water potentials of the exposed shoot treatment were lower (more negative) than for the whole plant covered treatment. Most of the water stress experienced by roots and shoots of both species accumulated during the first six weeks of storage. Water loss was greater for hawthorn stem sections than for maple during the first two weeks of storage. Results indicated that while protection of roots of all bare-root stock reduces water loss, sensitive species such as Washington hawthorn require both root and shoot protection to minimize water loss.

scholarly journals Biofilm Formation, Epiphytic Fitness, and Canker Development in Xanthomonas axonopodis pv. citri

2007 ◽  
Vol 20 (10) ◽  
pp. 1222-1230 ◽  
Author(s):  
Luciano A. Rigano ◽  
Florencia Siciliano ◽  
Ramón Enrique ◽  
Lorena Sendín ◽  
Paula Filippone ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Laser Scanning ◽  
Bacterial Attachment ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Phytopathogenic Bacterium ◽  
Canker Disease ◽  
Xanthomonas Axonopodis ◽  
Leaf Surfaces ◽  
Canker Development

The phytopathogenic bacterium Xanthomonas axonopodis pv. citri is responsible for the canker disease affecting citrus plants throughout the world. Here, we have evaluated the role of bacterial attachment and biofilm formation in leaf colonization during canker development on lemon leaves. Crystal violet staining and confocal laser scanning microscopy analysis of X. axonopodis pv. citri strains expressing the green fluorescent protein were used to evaluate attachment and biofilm formation on abiotic and biotic (leaf) surfaces. Wild-type X. axonopodis pv. citri attached to and formed a complex, structured biofilm on glass in minimal medium containing glucose. Similar attachment and structured biofilm formation also were seen on lemon leaves. An X. axonopodis pv. citri gumB mutant strain, defective in production of the extracellular polysaccharide xanthan, did not form a structured biofilm on either abiotic or biotic surfaces. In addition, the X. axonopodis pv. citri gumB showed reduced growth and survival on leaf surfaces and reduced disease symptoms. These findings suggest an important role for formation of biofilms in the epiphytic survival of X. axonopodis pv. citri prior to development of canker disease.

scholarly journals Myasthenia gravis and coronavirus disease 2019: A report from Iran

2021 ◽  
Author(s):  
Masoud Etemadifar ◽  
Mahsa Akafzadeh-Savari ◽  
Mehri Salari ◽  
Amirhossein Akhavan Sigari ◽  
Sara Ebrahimi-Pelarti ◽  
...  
Keyword(s):  
Cohort Study ◽  
Data Analysis ◽  
Myasthenia Gravis ◽  
Respiratory Muscle ◽  
Disease Duration ◽  
Neuromuscular Junctions ◽  
Clinical Status ◽  
Signs And Symptoms ◽  
Muscle Action ◽  
Increased Susceptibility

Background: Coronavirus disease 2019 (COVID-19) is spreading rapidly and has affected millions of people worldwide. Comorbid diseases have complicated the course of infection and increased mortality. Myasthenia gravis (MG) affects the neuromuscular junctions (NMJs) and can compromise respiratory muscle action, leading to worse clinical outcomes in individuals infected with the COVID-19 theoretically. In this study, the aim is to assess the pattern of COVID-19 infection in patients with MG based on several factors. Methods: This was a prospective cohort study following 150 patients with MG over a six-month period. The patients were monitored for the development of signs and symptoms of the COVID-19 infection. Results: Comparison of the patients infected with COVID-19 with MG and those not infected was performed independently based on age, duration since MG diagnosis, status of thymectomy, and current clinical status of MG disease. Data analysis did not reveal increased susceptibility or increased severity of COVID-19 illness based the criteria assessed. Conclusion: COVID-19 related deaths and susceptibility were not related to age, thymectomy status, and disease duration in patients with MG.  

scholarly journals Timing of Perennial Canker Development in Apple Trees Caused by Neofabraea perennans and Neofabraea kienholzii

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 555-562 ◽  
Author(s):  
Christian G. Aguilar ◽  
Mark Mazzola ◽  
Chang-Lin Xiao
Keyword(s):  
Fruit Trees ◽  
Apple Fruit ◽  
Pome Fruit ◽  
Apple Trees ◽  
Canker Disease ◽  
Aphid Control ◽  
Neofabraea Perennans ◽  
Rot Disease ◽  
Canker Development ◽  
Bull's Eye

Members of the genera Neofabraea and Phlyctema have been reported to incite canker diseases of apple trees and a postharvest decay of apple fruit referred to as “bull’s-eye rot.” Neofabraea kienholzii was recently identified as participating in the bull’s-eye rot disease complex of apple and other pome fruit. In this study, apple twigs inoculated with N. kienholzii were shown to develop symptoms of a canker disease closely resembling perennial canker of pome fruit trees caused by N. perennans. Cankers resulting from infection by either Neofabraea spp. were more likely to be induced when twig inoculations occurred in October, and to a lesser degree in April, compared with all other inoculation dates evaluated in this study. Although N. kienholzii tended to induce cankers that were smaller in size compared with N. perennans, both pathogens shared similar seasonal trends in the initiation and expansion of tree cankers. N. perennans and N. kienholzii were recovered from inoculated twigs 6 months postinoculation regardless of when inoculations were conducted, indicating that both pathogens can survive on diseased twigs year-round. In addition, acervuli were observed more often on twigs inoculated in September and April compared with those inoculated in other months. Data from this work should help further our understanding of the epidemiology of N. kienholzii. This information also highlights the importance of proper branch pruning, canker removal, and aphid control. Such management activities should be conducted in a manner that helps minimize further spread of the pathogen.

EFFECT OF COOLING RATE ON STORAGE LIFE OF PEARS

1965 ◽  
Vol 45 (1) ◽  
pp. 90-97
Author(s):  
S. W. Porritt
Keyword(s):  
Adverse Effects ◽  
Cooling Rate ◽  
Respiration Rate ◽  
Cold Storage ◽  
Storage Life ◽  
Rate Of Cooling ◽  
Increased Susceptibility

A study was made of the effect of rate of cooling after harvest on storage life of Bartlett pears. Delays in placing fruit in cold storage or failure to cool fruit rapidly once in cold storage markedly increased susceptibility to core breakdown, caused accelerated yellowing, and increased respiration rate of fruit in cold storage. These adverse effects of unfavorable cooling procedures were not necessarily accompanied by accelerated softening.

scholarly journals Control of Apple Scab and Cytospora Canker with Paclobutrazol

2012 ◽  
Vol 38 (3) ◽  
pp. 112-116
Author(s):  
Gary Watson ◽  
Karel Jacobs
Keyword(s):  
Disease Control ◽  
Growth Regulation ◽  
Apple Scab ◽  
Canker Disease ◽  
Significant Growth ◽  
Picea Pungens ◽  
The Third ◽  
Moderate Growth ◽  
Canker Development ◽  
Cytospora Canker

Forty Malus ‘Radiant’ crabapples, a variety known to be highly susceptible to apple scab disease, were field-planted then treated three months later with paclobutrazol (PBZ) as a basal drench, at rates of 0, 0.8, 1.6, and 2.4 g a.i./cm caliper. Apple scab was significantly reduced for two years post treatment by all rates of PBZ applied. However, significant growth regulation occurred through the third and final year of the study. Thirty Picea pungens (Colorado spruce) trees in containers were treated with PBZ, applied as a basal drench, at rates of 0, 1.6, and 3.2 g a.i./cm caliper. Cytospora canker development from subsequent branch inoculations was significantly reduced by both PBZ treatment rates and persisted through the end of the two year monitoring period. Cytospora canker disease control with only moderate growth regulation indicates that a PBZ basal drench could be developed into a viable landscape treatment.

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