Examining spatial distribution and spread of fire blight in apple orchards: two case studies

2021 ◽  
Author(s):  
Anna Wallis ◽  
Kerik Cox
Keyword(s):  
Spatial Distribution ◽  
Case Studies ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Spatial Analyses ◽  
Focal Points ◽  
Planting Material ◽  
Apple Production ◽  
Management Recommendations ◽  
Different Sources

Fire blight, caused by the bacteria Erwinia amylovora, is an incredibly destructive disease of apples, capable of spreading rapidly through an orchard block. The pathogen is endemic to many apple production regions worldwide, but it is often introduced into newly planted sites on infested host material, while locally it is typically vectored by wind driven rain, hail, and insects. Here we present two case studies of orchard blocks infected with fire blight at the Cornell AgriTech Research orchards in which CRISPR profile characterization was used to identify strains present in the blocks and spatial analyses were used to describe the distribution and spread of the disease over the course of two years. Results indicated two very different sources of introduction (a nearby block or planting material) and patterns of spread (from a corner of the field or from focal points within the block). Describing the distribution and spread of fire blight within and between orchard blocks has the potential to improve our understanding of the disease movement, inform appropriate management recommendations, and facilitate traceback efforts.

Investigating the distribution of strains of Erwinia amylovora and streptomycin resistance in apple orchards in New York using CRISPR profiles: a six-year follow-up

Plant Disease ◽  
2021 ◽  
Author(s):  
Anna Wallis ◽  
Isabella Magna Yannuzzi ◽  
Mei-Wah Choi ◽  
John Spafford ◽  
Matthew Siemon ◽  
...  
Keyword(s):  
New York ◽  
New England ◽  
Fire Blight ◽  
Management Practices ◽  
Erwinia Amylovora ◽  
Resistance Management ◽  
Strain Differences ◽  
Streptomycin Resistance ◽  
Management Recommendations

Fire blight, caused by the bacterium Erwinia amylovora, is one of the most important diseases of apple. The antibiotic streptomycin is routinely used in the commercial apple industries of New York and New England to manage the disease. In 2002, and again from 2011 to 2014, outbreaks of streptomycin resistance (SmR) were reported and investigated in NY. Motivated by new grower reports of control failures, we conducted a follow-up investigation of the distribution of SmR and E. amylovora strains for major apple production regions of NY over the last six years (2015-2020). Characterization of clustered regularly interspaced short palindromic repeat (CRISPR) profiles revealed that a few ‘cosmopolitan’ strains were widely prevalent across regions, while many other ‘resident’ strains were confined to one location. In addition, we uncovered novel CRISPR profile diversity in all investigated regions. SmR E. amylovora was detected only in a small area spanning two counties from 2017 to 2020, and always associated with one CRISPR profile (41:23:38), which matched the profile of SmR E. amylovora discovered in 2002. This suggests the original SmR E. amylovora was never fully eradicated and went undetected due to several seasons of low disease pressure in this region. Investigation of several representative isolates under controlled greenhouse conditions indicated significant differences in aggressiveness on ‘Gala’ apples. Potential implications of strain differences include the propensity of strains to become distributed across wide geographic regions and associated resistance management practices. Results from this work will directly influence sustainable fire blight management recommendations for commercial apple industries in NY State and other regions.

scholarly journals Evaluation of a Cider Apple Germplasm Collection of Local Cultivars from Spain for Resistance to Fire Blight (Erwinia amylovora) Using a Combination of Inoculation Assays on Leaves and Shoots

HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1223-1227 ◽  
Author(s):  
Alejandro Martínez-Bilbao ◽  
Amaya Ortiz-Barredo ◽  
Emilio Montesinos ◽  
Jesús Murillo
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Integrated Management ◽  
Germplasm Collection ◽  
Direct Selection ◽  
Breeding Programs ◽  
Detached Leaf ◽  
Apple Cultivars ◽  
Apple Production ◽  
Inoculation Assay

Fire blight, caused by the bacterium Erwinia amylovora, is among the three most important diseases of apple. A major effective method for its integrated management is the reduction of the susceptibility of the host. Cider apple production in Spain is based on local apple cultivars with minimum crop management and phytosanitary control. After the entry of fire blight in Spain, the selection and planting of cultivars with low susceptibility to this disease has thus become of paramount importance. In consequence, and as part of a wider characterization effort, we undertook the evaluation of an apple germplasm collection of local apple cultivars from Spain for susceptibility to fire blight. Because of the quarantine status of E. amylovora in Europe, we evaluated the use of a detached leaf inoculation assay in combination with a traditional shoot inoculation assay to reduce the amount of plant material to evaluate and to minimize pathogen manipulation. Comparison of the susceptibility values for 78 apple cultivars indicated a low but significant correlation (r = 0.56; α = 0.01) between the leaf and shoot inoculation methods. Although the detached leaf assay was not reliable for the direct selection of cultivars with low susceptibility, it was useful to optimize resources and limit the potential dispersal of the pathogen by allowing the exclusion of medium and highly susceptible cultivars from further evaluation. Shoot inoculation of 103 apple cultivars allowed the identification of 48 cultivars with high levels of resistance to fire blight, which could serve as starting material both for apple production and for breeding programs.

scholarly journals Testing a Rapid Diagnostic Medium for Erwinia amylovora and Development of a Procedure for Sampling Blossoms in Pear Orchards

2003 ◽  
Vol 93 (8) ◽  
pp. 931-940 ◽  
Author(s):  
G. Kritzman ◽  
H. Shwartz ◽  
R. Marcus ◽  
S. Manulis ◽  
F. Klietman ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Fatty Acid ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Sampling Procedure ◽  
Rapid Diagnosis ◽  
Sensitivity Analyses ◽  
Independent Data ◽  
Data Set ◽  
Accuracy Level

The coliform agar produced by Merck was tested for rapid diagnosis of Erwinia amylovora (the causal agent of fire blight) in pear blossoms. The medium enabled the diagnosis to be completed within 36 h. Diagnoses performed with the medium were confirmed by the BIOLOG and the fatty-acid profile methods. The diagnostic medium was used to determine the spatial distribution of colonized blossoms in the orchards and it was found that E. amylovora may be distributed both in clusters and at random. These findings were used in the development of a statistical model for sampling blossoms in the orchard. The model determines the number of trees to be sampled in the orchard and the number of blossoms be taken from each tree, which would enable the true colonization incidence of blossoms in the orchard to be estimated at desired levels of accuracy and confidence. Parameters included in the model are: the total number of trees in the orchard (T), the number of trees to be sampled in the orchard (t), the number of blossoms to be sampled from each tree (n), the true colonization incidence of blossoms (π), a coefficient of aggregation (ρ), the required level of confidence (1 - α), and the required level of accuracy (L). Sensitivity analyses revealed that the parameter governing sample size is the required level of accuracy. Sampling of 20 blossoms from each of several hundred trees is required to achieve an accuracy of ±1%, but only a few single trees are needed for an accuracy level of ±10%. A sampling procedure then was developed, validated with an independent data set, and found to be accurate. It was concluded that sampling of pear blossoms and estimation of the incidence of blossom colonization by E. amylovora could improve fire blight management, but not in all cases.

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.

A Pandemic of Violence? The Impact of COVID-19 on Conflict

2020 ◽  
Vol 26 (3) ◽  
Author(s):  
Sara M.T. Polo
Keyword(s):  
Spatial Distribution ◽  
Real Time ◽  
Case Studies ◽  
Armed Conflict ◽  
Event Data ◽  
Social Unrest ◽  
Johns Hopkins University ◽  
The World ◽  
Political Advantage ◽  
The Impact

AbstractThis article examines the impact and repercussions of the COVID-19 pandemic on patterns of armed conflict around the world. It argues that there are two main ways in which the pandemic is likely to fuel, rather than mitigate, conflict and engender further violence in conflict-prone countries: (1) the exacerbating effect of COVID-19 on the underlying root causes of conflict and (2) the exploitation of the crisis by governments and non-state actors who have used the coronavirus to gain political advantage and territorial control. The article uses data collected in real-time by the Armed Conflict Location & Event Data Project (ACLED) and the Johns Hopkins University to illustrate the unfolding and spatial distribution of conflict events before and during the pandemic and combine this with three brief case studies of Afghanistan, Nigeria, and Libya. Descriptive evidence shows how levels of violence have remained unabated or even escalated during the first five months of the pandemic and how COVID-19-related social unrest has spread beyond conflict-affected countries.

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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