Survival of the fire blight pathogen, Erwinia amylovora, in calyxes of apple fruit discarded in an orchard

2003 ◽  
Vol 22 (4) ◽  
pp. 603-608 ◽  
Author(s):  
R.K Taylor ◽  
C.N Hale ◽  
F.A Gunson ◽  
J.W Marshall
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Apple Fruit

scholarly journals Evaluation of Loop-Mediated Isothermal Amplification for Rapid Detection of Erwinia amylovora on Pear and Apple Fruit Flowers

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 423-430 ◽  
Author(s):  
Todd N. Temple ◽  
Kenneth B. Johnson
Keyword(s):  
Rapid Detection ◽  
Pathogen Detection ◽  
Fire Blight ◽  
Management Practices ◽  
Erwinia Amylovora ◽  
Lamp Assay ◽  
Apple Fruit ◽  
Isothermal Amplification ◽  
Loop Mediated Isothermal Amplification ◽  
Forecasting Models

Fire blight of pear and apple is frequently an inoculum-limited disease but weather-based forecasting models commonly assume that the pathogen is omnipresent. To improve fire blight risk assessment during flowering, we developed a rapid pathogen detection protocol that uses loop-mediated isothermal amplification (LAMP) to detect DNA of epiphytic Erwinia amylovora on samples of pear and apple flowers. LAMP detected a single flower colonized epiphytically by E. amylovora in a sample of 100 flower clusters (approximately 600 flowers). Samples of 100 flower clusters from orchards (approximately one sample per hectare) were washed and subjected to LAMP, which was completed in 2 h. In three experimental orchards inoculated with E. amylovora, positive LAMP reactions were attained from nine of nine 100-flower cluster samples; pathogen populations in the floral washes averaged 5.2 × 103 CFU per flower as determined by dilution plating. Samples of pear and apple flowers obtained from 60 commercial orchards located in Oregon, Washington, California, and Utah resulted in detection of E. amylovora by LAMP assay from 34 sites, 20 of which developed fire blight. Of samples at early bloom, 10% were positive for epiphytic E. amylovora compared with 28% at petal fall; pathogen density in washes of positive samples averaged 3.2 × 102 CFU per flower. In another 26 orchards, all floral washes were negative for E. amylovora by LAMP and by dilution plating; a light severity of fire blight was observed in 8 of these orchards. Overall, positive detection of epiphytic E. amylovora in commercial orchards by LAMP-based scouting generally occurred at later stages of bloom after heat (risk) units had begun to accumulate, an indication that weather-based forecasting models may be an adequate measure of fire blight risk for many orchardists. Nonetheless, several orchardists communicated that information from the LAMP-based rapid detection protocol resulted in modification of their fire blight management practices.

scholarly journals Evaluation of Strategies for Fire Blight Control in Organic Pome Fruit Without Antibiotics

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 402-409 ◽  
Author(s):  
Kenneth B. Johnson ◽  
Todd N. Temple
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Antibiotic Use ◽  
Apple Fruit ◽  
Pome Fruit ◽  
Biological Products ◽  
Control Programs ◽  
National Organic Program ◽  
Antibiotic Control ◽  
Fruit Load

Apple and pear produced organically under the U.S. National Organic Program (NOP) standard can be treated with antibiotics for suppression of fire blight caused by Erwinia amylovora. Recent regulatory actions by the NOP, however, have lessened the likelihood of antibiotic use after the 2014 season. In response, western U.S. organic apple and pear stakeholders identified two immediate-need research objectives related to fire blight control: development of effective non-antibiotic control programs based on combinations of registered biological products; and, in apple, integration of these products with lime sulfur, which is sprayed at early bloom to reduce fruit load. In orchard trials in Oregon, increasing the frequency of treatment with biological products improved suppression of floral infection. In apple, fruit load thinning with 2% lime sulfur plus 2% fish oil (LS+FO) at 30 and 70% bloom significantly (P ≤ 0.05) reduced the proportion of blighted flower clusters in four of five orchard trials. Moreover, lime sulfur significantly (P ≤ 0.05) suppressed epiphytic populations of E. amylovora after their establishment on apple flowers. Over four trials, treatment with Aureobasidium pullulans (Blossom Protect) after LS+FO reduced the incidence of fire blight by an average of 92% compared with water only; this level of control was similar to treatment with streptomycin. In three seasons, a spray of a Pantoea agglomerans product after the 70% bloom treatment of LS+FO established the antagonist on a significantly (P ≤ 0.05) higher proportion of flowers compared with a spray of this bacterium before the thinning treatment. Consequently, in apple, biological treatments for fire blight control are not advised until after lime sulfur treatments for fruit load thinning are completed.

The potential for spread of Erwinia amylovora and fire blight via commercial apple fruit; a critical review and risk assessment

1998 ◽  
Vol 17 (1) ◽  
pp. 19-28 ◽  
Author(s):  
R.G. Roberts ◽  
C.N. Hale ◽  
T. van der Zwet ◽  
C.E. Miller ◽  
S.C. Redlin
Keyword(s):  
Risk Assessment ◽  
Critical Review ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Apple Fruit

scholarly journals Functional characterization of the adenine transporter EaAdeP from the fire blight pathogen Erwinia amylovora and its effect on disease establishment in apples and pears

2020 ◽  
Vol 367 (20) ◽  
Author(s):  
Candace R Alexander ◽  
Regan B Huntley ◽  
Neil P Schultes ◽  
George S Mourad
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Functional Characterization ◽  
Biochemical Properties ◽  
Apple Fruit ◽  
Infection Process ◽  
Disease Symptoms ◽  
Uptake Studies ◽  
Important Disease

ABSTRACT Erwinia amylovora is the causal agent of fire blight, an economically important disease of apples and pears. As part of the infection process, Er. amylovora propagates on different plant tissues each with distinct nutrient environments. Here, the biochemical properties of the Er. amylovora adenine permease (EaAdeP) are investigated. Heterologous expression of EaAdeP in nucleobase transporter-deficient Escherichia coli strains, coupled with radiolabel uptake studies, revealed that EaAdeP is a high affinity adenine transporter with a Km of 0.43 ± 0.09 μM. Both Es. coli and Er. amylovora carrying extra copies of EaAdeP are sensitive to growth on the toxic analog 8-azaadenine. EaAdeP is expressed during immature pear fruit infection. Immature pear and apple fruit virulence assays reveal that an E. amylovora ΔadeP::Camr mutant is still able to cause disease symptoms, however, with growth at a lower level, indicating that external adenine is utilized in disease establishment.

Fire Blight Susceptibility in Pyrus Germplasm from Eastern Europe

HortScience ◽  
1990 ◽  
Vol 25 (5) ◽  
pp. 566-568 ◽  
Author(s):  
T. van der Zwet ◽  
R.L. Bell
Keyword(s):  
Eastern Europe ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Breeding Program ◽  
Plant Germplasm ◽  
Plant Exploration ◽  
Moderately Resistant

During 1976-1980, three plant exploration trips were made throughout eastern Europe in search of native Pyrus germplasm. A total of 384 accessions (231 from Yugoslavia, 86 from Romania, 43 from Poland, and 12 each from Hungary and Czechoslovakia) were collected as budwood and propagated at the National Plant Germplasm Quarantine Center in Glenn Dale, Md. Following 8 years of exposure to the fire blight bacterium [Erwinia amylovora (Burr.) Winsl. et al.], 17.49” of the accessions remained uninfected, 11.2% rated resistant, 6.8% moderately resistant, and 64.6% blighted severely (26% to 100% of tree blighted). Some of the superior accessions have been released for use in the pear breeding program.

scholarly journals Isolation and efficacy of two bacterial strains antagonists of Erwinia amylovora and Pectobacterium carotovorum

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
M’hamed BENADA ◽  
Boualem BOUMAAZA ◽  
Sofiane BOUDALIA ◽  
Omar KHALADI
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Species ◽  
Crop Protection ◽  
Soft Rot ◽  
Causal Agent ◽  
Plant Diseases ◽  
Ecological Niches ◽  
Pectobacterium Carotovorum ◽  
Bacterial Strains

Abstract Background The development of ecofriendly tools against plant diseases is an important issue in crop protection. Screening and selection process of bacterial strains antagonists of 2 pathogenic bacterial species that limit very important crops, Erwinia amylovora, the causal agent of the fire blight disease, and Pectobacterium carotovorum, the causal agent of bacterial potato soft rot, were reported. Bacterial colonies were isolated from different ecological niches, where both pathogens were found: rhizosphere of potato tubers and fruits and leaves of pear trees from the northwest region of Algeria. Direct and indirect confrontation tests against strains of E. amylovora and P. carotovorum were performed. Results Results showed a significant antagonistic activity against both phytopathogenic species, using direct confrontation method and supernatants of cultures (p<0.005). In vitro assays showed growth inhibitions of both phytopathogenic species. Furthermore, results revealed that the strains of S. plymuthica had a better inhibitory effect than the strains of P. fluorescens against both pathogens. In vivo results on immature pear fruits showed a significant decrease in the progression of the fire blight symptoms, with a variation in the infection index from one antagonistic strain to another between 31.3 and 50%, and slice of potato showed total inhibition of the pathogen (P. carotovorum) by the antagonistic strains of Serratia plymuthica (p<0.005). Conclusion This study highlighted that the effective bacteria did not show any infection signs towards plant tissue, and considered as a potential strategy to limit the fire blight and soft rot diseases.

Isolation and characterization of Hena1 – a novel Erwinia amylovora bacteriophage

2020 ◽  
Vol 367 (9) ◽  
Author(s):  
Natalya V Besarab ◽  
Artur E Akhremchuk ◽  
Maryna A Zlatohurska ◽  
Liudmyla V Romaniuk ◽  
Leonid N Valentovich ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Fire Blight ◽  
Antimicrobial Agents ◽  
Erwinia Amylovora ◽  
Gc Content ◽  
Control Measures ◽  
Effective Control ◽  
Lytic Phage ◽  
Trna Genes ◽  
Isolation And Characterization

ABSTRACT Fire blight, caused by plant pathogenic bacterium Erwinia amylovora, is one of the most important diseases of Rosaceae plants. Due to the lack of effective control measures, fire blight infections pose a recurrent threat on agricultural production worldwide. Recently, bacterial viruses, or bacteriophages, have been proposed as environmentally friendly natural antimicrobial agents for fire blight control. Here, we isolated a novel bacteriophage Hena1 with activity against E. amylovora. Further analysis revealed that Hena1 is a narrow-host-range lytic phage belonging to Myoviridae family. Its genome consists of a linear 148,842 bp dsDNA (48.42% GC content) encoding 240 ORFs and 23 tRNA genes. Based on virion structure and genomic composition, Hena1 was classified as a new species of bacteriophage subfamily Vequintavirinae. The comprehensive analysis of Hena1 genome may provide further insights into evolution of bacteriophages infecting plant pathogenic bacteria.

INVESTIGATION ON DETERMINING SOME PEAR VARIETIES RESISTANT TO FIRE BLIGHT (ERWINIA AMYLOVORA (BURRILL) WINSLOW ET AL.)

1999 ◽  
pp. 225-228 ◽  
Author(s):  
H. Saygili ◽  
H. Türküsay ◽  
S. Hepaksoy ◽  
A. Ünal ◽  
H.Z. Can
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora
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