scholarly journals Blackberry and raspberry are alternative resistance sources to fire blight

2017 ◽  
Vol 97 (1) ◽  
pp. 12-16 ◽  
Author(s):  
Ozer Calis ◽  
Cetin Cekic ◽  
Serhat Kara ◽  
Demet Celik Ertekin
Keyword(s):  
Bacterial Growth ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Pathogen ◽  
Post Inoculation ◽  
Resistance Sources ◽  
Pathogenicity Tests ◽  
Susceptibility And Resistance ◽  
Resistant Genotypes ◽  
Moderate Susceptibility

Erwinia amylovora causes fire blight mainly on pear, apple and quince trees. This bacterial pathogen also infects other Rosaceous plants, such as blackberry and raspberry. A race structure was established between an isolate of E. amylovora and berries using 40 wild blackberry and 7 wild raspberry genotypes. In pathogenicity tests, wild blackberry and raspberry genotypes had three phenotypic reactions: enhanced susceptibility, moderate susceptibility and resistance. We noted a higher bacterial growth of over 300 × 109 cfu mL-1 in plants with enhanced susceptibility, with resistant genotypes showing a bacterial growth of around 150 × 109 cfu mL-1. These results are also associated with symptoms observed at 29 days post-inoculation. This resistance is being evaluated to control fire blight.

scholarly journals Resistance of apple varieties and selections to Erwinia amylovora in the Czech Republic

2008 ◽  
Vol 44 (No. 3) ◽  
pp. 91-96 ◽  
Author(s):  
J. Korba ◽  
J. Šillerová ◽  
V. Kůdela
Keyword(s):  
Czech Republic ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Relative Resistance ◽  
Lesion Development ◽  
The Czech Republic ◽  
Apple Cultivars ◽  
Moderately Resistant ◽  
Resistant Genotypes ◽  
Experimental Plots

Sixty-four apple cultivars and selections of potential interest to apple producers and plant breeders in the Czech Republic were tested for their relative resistance to the fire blight pathogen over six years. Level of fire blight resistance was evaluated according to the extent of lesion development on the shoots tips after artificial inoculation in experimental plots under insectproof nets. Cultivars Quinte (resistant) and Yellow transparent (high susceptible) were included in the tests. Of 64 apple cultivars and selections tested, none were high resistant, 3.1% were evaluated as resistant, 10.9% moderately resistant, 57.8% moderately susceptible, 21.9% susceptible and 6.3% high susceptible. Resistant apple genotypes, showing blight necrosis of shoots of 11–12%, were only cultivars Selena and Quinte. Moderately resistant genotypes (blight necrosis 13.1–25.0%) were Kordona, Golden Smoothee, Julia, HL 323, Melodie, HL 421 and S 634/3. High susceptible genotypes (blight necrosis more then 80.1%) were comprised cultivars Vesna, Topas, Yellow transparent and Vanda. The remaining genotypes were moderately susceptible (blight necrosis 26.1–60.0%) and susceptible (blight necrosis 60.1–80.0%). During six experimental years, quantitative variability was recorded in the blight score. Differences between cultivars in susceptibility to fire blight were often statistically significant.

scholarly journals Evaluation of susceptibility level of pear cultivars to fire blight (Erwinia amylovora) in the Czech Republic

2013 ◽  
Vol 40 (No. 2) ◽  
pp. 58-64 ◽  
Author(s):  
J. Korba ◽  
J. Šillerová ◽  
F. Paprštein ◽  
J. Sedlák ◽  
E. Prokinová ◽  
...  
Keyword(s):  
Czech Republic ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
The Czech Republic ◽  
Resistant Genotype ◽  
Proof Nets ◽  
Breeding Selection ◽  
Moderately Resistant ◽  
Resistant Genotypes ◽  
Alexander Lucas

Thirty-three pear cultivars and selections of potential interest to pear producers and plant breeders in the Czech Republic were tested for relative field susceptibility to the fire blight (Erwinia amylovora) over five years. Level of fire blight susceptibility was evaluated according to the extent of lesion development on the shoot tips after artificial inoculation in experimental plots under insect proof nets. Old cvs Alexander Lucas (as resistant standard), Conference (as moderately resistant standard) and Beurré Bosc (as susceptible standard) were included in the tests. The 33 pear cultivars and selections were tested, only one of them was highly resistant (3.0%), 3.0% were evaluated as resistant, 12.1% moderately resistant, 36.4% moderately susceptible, 18.2% susceptible and 27.3% highly susceptible. Breeding selection US 625-63-10 was the only highly resistant pear genotype (necrosis of shoots of 0–7.0%). Resistant genotype group (necrosis 7.1–13.0%) comprised US 625-63-4. Moderately resistant genotypes (necrosis 13.1–25.0%) included cvs Alexander Lucas, Alfa, Bohemica and HL 31-50-31. Highly susceptible genotypes (necrosis more than 80.1%) included cvs Vonka, Karina, Bona, Decora, Elektra, Milka, Regina, Alice and TE 4763. The remaining genotypes were moderately susceptible (necrosis 26.1–60.0%) and susceptible (necrosis 60.1–80.0%).    

scholarly journals Effect of prohexadionecalcium on nectar composition of pomaceous flowers and on bacterial growth

2005 ◽  
Vol 58 ◽  
pp. 106-111
Author(s):  
F. Spinelli ◽  
J.L Vanneste ◽  
G.L. Marcazzjin ◽  
A.G. Sabatini ◽  
G. Costa
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Bacterial Growth ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Pantoea Agglomerans ◽  
Sugar Concentration ◽  
Sugar Solution ◽  
Biological Control Agents ◽  
Nectar Composition

Prohexadionecalcium is an acylcyclohexanedione that reduces incidence of fire blight caused by Erwinia amylovora To determine whether prohexadionecalcium can be used in conjunction with biological control agents its effect on the secretion and composition of nectar from apple and pear flowers was evaluated Plants treated with prohexadionecalcium produced more nectar but the sugar concentration of the nectar was lower The ability of E amylovora and of two biological control agents of fire blight Pantoea agglomerans and Pseudomonas fluorescens to grow in a sugar solution corresponding to the composition of nectar from treated or untreated plants was determined in the laboratory All bacteria including E amylovora grew better in the sugar solution corresponding to the nectar from treated plants The concentration of sugar in the nontreated flowers may be too high for bacterial growth These results also suggest that prohexadionecalcium can be used alongside biological control agents for reduction of fire blight incidence

scholarly journals Floral biological investigations of apple cultivars in relation to fire blight

2004 ◽  
Vol 10 (2) ◽  
Author(s):  
Zs. Orosz-Kovács ◽  
A. Farkas ◽  
T. Bubán ◽  
P. Bukovics ◽  
E. Nagy Tóth ◽  
...  
Keyword(s):  
Bacterial Growth ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Optimal Conditions ◽  
Nectar Secretion ◽  
Flower Bud ◽  
Nectar Production ◽  
Sem Micrographs ◽  
Long Period ◽  
Apple Cultivars

Floral activity was studied in two apple cultivars: an Erwinia-tolerant (Treedorn') and a sensitive one (`Sampion'). Since more types of protogyny occur in apples, the period of stigma activity is different. Papillae of the exposed stigma in flowers of 'Freedom' function longer (usually more than a week) than in the delayed homogamous `Sampion'. Despite of this, cv. 'Freedom' is tolerant to Erwinia amylovora (Burr.) Winslow et al., suggesting no relationship between the floral biological type (including the exposure and longevity of stigma) and the infection by E. amylovora. According to SEM micrographs, nectary stomata in `Freedom' are already open in the flower bud, where nectar secretion starts and continues until the senescence of the stigma. However, the long period of nectar secretion does not create optimal conditions for bacterial growth, since nectar production is scant in the flowers of 'Freedom'. The surface of the nectary, its nectar-retaining capacity, and the amount and concentration of nectar may influence the susceptibility of apple cultivars. It is manifested well by the smooth nectary surface with nectary stomata rising slightly above the epidermis in flowers of cv. 'Freedom', contrasting the wrinkled, striate nectary surface with slightly sunken stomata in the flowers of 'Sampion'.

Characteristics of Erwinia amylovora bacteriophage and its possible role in the epidemiology of fire blight

1973 ◽  
Vol 19 (7) ◽  
pp. 837-845 ◽  
Author(s):  
J. M. Erskine
Keyword(s):  
Uv Irradiation ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Resistant Mutant ◽  
Fruit Trees ◽  
Symptom Development ◽  
Phage Resistant Mutant ◽  
Pathogenicity Tests ◽  
Optimal Efficiency ◽  
Blight Disease

Bacteriophage (S1) of Erwinia amylovora, isolated from soil at the base of fire-blight-infected trees, was characterized by small, clear plaques on E. amylovora strain PR1 and hazy plaques of the same size on a closely related, yellow, saprophytic bacterium, Y, which was isolated together with PR1 from the diseased trees. Phage S1 plated with optimal efficiency at 10C on PR1 and at 28C on Y was relatively unstable to storage at temperatures typical of summer and to ultraviolet (UV) irradiation, and lysogenized Y but not PR1. Pathogenicity tests in pear slices demonstrated that symptom development was (i) delayed when mixtures of either PR1 and phage S1 or PR1 and Y were inoculated, (ii) delayed when a culture of a phage-resistant mutant of PR1 was inoculated, and (iii) prevented from appearing at all when PR1 and the lysogenic form of Y, Y (S1), were inoculated together. Strain Y was easily lysogenized and Y (S1) released phage spontaneously and after UV irradiation. It is suggested that the yellow saprophyte, which is invariably isolated from fruit trees with E. amylovora, may frequently occur in its lysogenic form in nature and serve as a reservoir of phage which may exert some influence on the occurrence and severity of fire-blight disease.

scholarly journals Spread of fire blight in Austria  and Hungary – variability of Erwinia amylovora strains

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S49-S55 ◽  
Author(s):  
M. Keck ◽  
M. Hevesi ◽  
W. Ruppitsch ◽  
A. Stöger ◽  
S. Richter
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Epifluorescence Microscopy ◽  
Aflp Analysis ◽  
Bacterial Strains ◽  
Pcr Rflp ◽  
Pathogenicity Tests ◽  
Apple Cultivars ◽  
Cellular Defence ◽  
Plant Susceptibility

First outbreaks of fire blight were detected in Austria in 1993 and in Hungary in 1995. 137 Erwinia amylovora isolates were compared by PCR-RFLP, sequencing of the repeat region of the PstI fragment of plasmid pEA29, RAPD and AFLP analysis. Differences of repeat numbers in first isolates were observed. Six isolates showed different RAPD profiles. In AFLP analysis, so far, no differences in fragment pattern were determined. Pathogenicity tests with micropropagated apple cultivars revealed differences in plant susceptibility and in virulence of isolates. Responses of Malus tissue were visualized by the use of epifluorescence microscopy through the localization and the production of substances involved in cellular defence mechanisms (e.g. flavonoids, lignin) in various susceptible cultivars. The effect of bacterial strains differing in pathogenicity is shown by cellular peroxidase and flavonoid production.

In-orchard population dynamics of Erwinia amylovora on apple flower stigmas

2022 ◽  
Author(s):  
Suzanne Slack ◽  
Jeff Schachterle ◽  
Emma Sweeney ◽  
Roshni Kharadi ◽  
Jingyu Peng ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Wind Speed ◽  
Relative Humidity ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Field Studies ◽  
Post Inoculation ◽  
Time Period ◽  
Weather Parameters ◽  
Frequent Sampling

Populations of the fire blight pathogen Erwinia amylovora Ea110 on apple flower stigmas were tracked over the course of apple bloom in field studies conducted between 2016 and 2019. In 18 of 23 experiments, flower stigmas inoculated on the 1st day of opening were found to harbor large (106-107 cells / flower) populations of E. amylovora when assessed three to five days post-inoculation. However, populations inoculated on stigmas of flowers that were already open for three days did not reach 106 cells / flower, and populations inoculated on stigmas of flowers that were already open for five days never exceeded 104 cells / flower. During this study, >10-fold increases in E. amylovora stigma populations in a 24-hr time period (termed population surges) were observed on 34.8%, 20.0%, and 4.0% of possible days on 1-day, 3-day, and 5-day open flowers, respectively. Population surges occurred on days with average temperatures as high as 24.5°C and as low as 6.1°C. Experiments incorporating more frequent sampling during days and overnight revealed that many population surges occurred between 10:00 PM and 2:00 AM. A Pearson’s correlation analysis of weather parameters occurring during surge events indicated that population surges were significantly associated with situations where overnight temperatures either increased or remained constant, where wind speed decreased, and where relative humidity increased. This study refines our knowledge of E. amylovora population dynamics and further indicates that E. amylovora is able to infect flowers during exposure to colder field temperatures than previously reported.

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.

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