Evaluation of biological control of Erwinia amylovora, causal agent of fire blight disease of pear by antagonistic bacteria

The influence of flower age on growth of Erwinia amylovora, the causal pathogen of fire blight of apples and pears, was investigated under humid and arid conditions in Hamilton, New Zealand (NZ), and Logan, UT, USA, respectively. ‘Royal Gala’ apple flowers ranging from 1 to 8 days old were atomized with E. amylovora. Pistils were dissected and washed separately from the remaining floral parts (flowers ex pistils) for estimation of bacterial numbers. Pistils, 1 to 3 days old (USA) and 1 to 4 days old (NZ), supported exponential growth of E. amylovora, but bacterial populations did not increase when older flowers were inoculated. Scanning electron microscopy showed round and turgid papillae on stigmas of 1-day-old flowers. Papillae on 4- to 6-day-old stigmas were completely collapsed and covered in mucilage. Populations of E. amy-lovora on the flowers ex pistils were characteristically lower than pistil populations. High populations of saprophytic bacteria were found on both floral parts of all ages, but there was no difference in their numbers on 3- to 6-day-old pistils. This suggests their presence did not inhibit the growth of E. amylovora on older stigmas. The results demonstrate that stigmas on 1- to 3-day-old flowers often support rapid growth of E. amylovora, but flowers inoculated when more than 4 to 5 days old do not support growth or only limited growth. The same location and pattern of bacterial growth occurred with the biological control agents Pseudomonas fluorescens PfA506n and Pantoea agglomerans (Erwinia herbicola) Eh318nr. The distinct effect of flower age on growth of antagonistic bacteria and E. amylovora may be important in deciding when to treat with biological control organisms or bactericides.

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Molecular Mechanisms of Pathogenesis and Resistance to the Bacterial Pathogen Erwinia amylovora, Causal Agent of Fire Blight Disease in Rosaceae

Plant Molecular Biology Reporter ◽

10.1007/s11105-011-0334-1 ◽

2011 ◽

Vol 30 (2) ◽

pp. 247-260 ◽

Cited By ~ 62

Author(s):

M. Awais Khan ◽

Youfu Zhao ◽

Schuyler S. Korban

Keyword(s):

Fire Blight ◽

Molecular Mechanisms ◽

Erwinia Amylovora ◽

Bacterial Pathogen ◽

Causal Agent ◽

Blight Disease

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Antibacterial Activity of Antagonistic Bacteria and Plant Extract on Erwinia amylovora the Pathogen of Fire Blight Disease in Egypt

International Journal of Phytopathology ◽

10.33687/phytopath.004.02.1187 ◽

2015 ◽

Vol 4 (2) ◽

pp. 73-79 ◽

Cited By ~ 3

Author(s):

Khaled H. Arafat ◽

Shaheen A. Hanan ◽

Abd-El-Aziz M. Rabab

Keyword(s):

Plant Extract ◽

Large Scale ◽

Fire Blight ◽

Erwinia Amylovora ◽

Management Program ◽

Antagonistic Bacteria ◽

Pear Trees ◽

Blight Disease

The blossom blight phase of fire blight disease on pear trees, caused by the bacterium Erwinia amylovora (Burrill), was typically managed by applying the antibiotic, streptomycin sulfate and copper, to trees during blossom. Biological control agents of fire blight can be achieved by applying nonpathogenic bacteria, viz. Bacillus subtilis or Pantoea agglomerans and plant extract, viz. Harmel (Peganum harmala L.) during open flowers as spraying treatments. The objective of this study was to examine the alternative bactericides against bacterium E. amylovora in vitro and in vivo during two seasons (2013-2014) in Al-Gharbia governorate, Egypt. Our results revealed the ability of these antagonistic bacteria and plant extract can decreased fire blight severity on pear trees. Further studies at different locations in Egypt with large scale application would allow us to make stronger recommendations including their ability to prevent disease and used them as main component in integrated pest management program.

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

Egyptian Journal of Biological Pest Control ◽

10.1186/s41938-021-00443-0 ◽

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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Fire Blight Symptomatic Shoots and the Presence of Erwinia amylovora in Asymptomatic Apple Budwood

Plant Disease ◽

10.1094/pdis-06-16-0892-re ◽

2017 ◽

Vol 101 (1) ◽

pp. 186-191 ◽

Cited By ~ 3

Author(s):

K. A. Tancos ◽

E. Borejsza-Wysocka ◽

S. Kuehne ◽

D. Breth ◽

Kerik D. Cox

Keyword(s):

New York ◽

Fire Blight ◽

Erwinia Amylovora ◽

Causal Agent ◽

Economic Losses ◽

Apple Trees ◽

The Mean ◽

Collection Practices ◽

Time Of Collection ◽

Young Apple

Erwinia amylovora, the causal agent of fire blight, causes considerable economic losses in young apple plantings in New York on a yearly basis. Nurseries make efforts to only use clean budwood for propagation, which is essential, but E. amylovora may be present in trees that appear to have no apparent fire blight symptoms at the time of collection. We hypothesized that the use of infected budwood, especially by commercial nursery operations, could be the cause, in part, of fire blight outbreaks that often occur in young apple plantings in New York. Our goal was to investigate the presence of E. amylovora in asymptomatic budwood from nursery source plantings as it relates to trees with fire blight symptoms. From 2012 to 2015, apple budwood was collected from two commercial budwood source plantings of ‘Gala’ and ‘Topaz’ at increasing distances from visually symptomatic trees. From these collections, internal contents of apple buds were analyzed for the presence of E. amylovora. E. amylovora was detected in asymptomatic budwood in trees more than 20 m from trees with fire blight symptoms. In some seasons, there were significant (P ≤ 0.05) differences in the incidence of E. amylovora in asymptomatic budwood collected from symptomatic trees and those up to 20 m from them. In 2014 and 2015, the mean E. amylovora CFU per gram recovered from budwood in both the Gala and Topaz plantings were significantly lower in budwood collected 20 m from symptomatic trees. Further investigation of individual bud dissections revealed that E. amylovora was within the tissue beneath the bud scales containing the meristem. Results from the study highlight the shortcomings of current budwood collection practices and the need to better understand the factors that lead to the presence of E. amylovora in bud tissues to ensure the production of pathogen-free apple trees.

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Evaluation of Susceptibility of Different Pear Hybrid Populations to Fire Blight (Erwinia amylovora)

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha3915619 ◽

2011 ◽

Vol 39 (1) ◽

pp. 226 ◽

Cited By ~ 2

Author(s):

Yasemin EVRENOSOĞLU ◽

Adalet MISIRLI ◽

Hikmet SAYGILI ◽

Emre BİLEN ◽

Özlem BOZTEPE ◽

...

Keyword(s):

Fire Blight ◽

Erwinia Amylovora ◽

Open Pollination ◽

Resistance Level ◽

Class A ◽

Class B ◽

Artificial Inoculations ◽

Serious Disease ◽

Blight Disease ◽

Santa Maria

Fire blight disease caused by pathogenic bacterium Erwinia amylovora, is the serious disease of pear, and there is not a certain chemical management against this disease except antibiotic-type compounds such as streptomycin. It is very important to improve new fire blight resistant cultivars in case of integrated disease management. With this purpose, different crosses have been made between Pyrus communis varieties that have good fruit characteristics and resistant cultigens. Besides, self and open pollination treatments have been carried out in maternal plants. The disease resistance level of the hybrids obtained from these combinations was determined by artificial inoculations by Erwinia amylovora in greenhouse conditions. A total of 3284 hybrids were inoculated, and 2631 of them survived and were distributed to different susceptibility classes. 19.88% of the inoculated hybrids was killed by Erwinia amylovora. Total distribution of the hybrids to susceptibility classes was as 6.18% in class “A- slightly susceptible”, 3.11% in class “B- less susceptible”, 8.89% in class “C- mid-susceptible”, 20.28% in class “D- susceptible”, and 61.54% in class “E- very susceptible”. Majority of class “A- slightly susceptible” hybrids were obtained from ‘Magness’ x ‘Ankara’ combination. ‘Kieffer’ x ‘Santa Maria’, ‘Kieffer’ open pollination, ‘Magness’ x ‘Akça’, ‘Magness’ x ‘Kieffer’, ‘Magness’ x ‘Santa Maria’, ‘Mustafa Bey’ x ‘Moonglow’ treatments displayed good results with respect to “A- slightly susceptible” character. It is very important to evaluate these hybrid pear populations through different fruit and tree characteristics in the future.

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