scholarly journals Extensive efficacy tests of non-antibiotic fire blight control agents

2020 ◽  
Author(s):  
Georg Bantleon ◽  
Christian Scheer ◽  
Karin Hartung ◽  
Ralf T. Voegele
Keyword(s):  
Fire Blight ◽  
Legal Status ◽  
High Efficacy ◽  
Resistance Development ◽  
Potential Control ◽  
Extensive Evaluation ◽  
Shoot Blight ◽  
Potassium Aluminum Sulfate ◽  
Antibiotic Agents ◽  
Antibiotic Control

AbstractApplication of control agents to prevent new infections is an integral part of disease management for fire blight on pome trees caused by Erwinia amylovora (Burrill) Winslow et al.. Due to resistance development and human health concerns when using antibiotics, non-antibiotic control agents with high efficacy are urgently needed. In this study extensive efficacy tests with some classical antibiotic and relatively new non-antibiotic control agents for the prevention of bloom and shoot blight as well as phytotoxicity tests based on fruit russeting were carried out using young apple trees. Furthermore an experimental design for testing control agents preventing fire blight following hail injury was developed. The high efficacy of streptomycin (> 90%) and streptomycin containing spray strategies (> 80%) was confirmed. Non-antibiotic agents with high efficacy are LMA (85%), a potassium aluminum sulfate, and Juglon (80%). LMA is already in use in practice in Austria and Germany with a temporal and restricted permission and the administrative process to gain the legal status of a pesticide is ongoing whilst already admitted in Switzerland. Juglon, an organic compound from walnut, did show a high efficacy, but no consistent results (80.0 and 69.5%). Myco-Sin showed good results to prevent infection after artificial hail simulation. Antinfek showed high efficacy (90%) in preventing bloom blight, but could be tested only once so further research is needed to confirm this result. The design of the presented study enabled an extensive evaluation of the potential control agents and the aggregation and comparison of results and can be advised for other evaluations.

scholarly journals Management of Fire Blight Using Pre-bloom Application of Prohexadione-Calcium

Plant Disease ◽  
2020 ◽  
Vol 104 (4) ◽  
pp. 1048-1054
Author(s):  
Anna E. Wallis ◽  
Kerik D. Cox
Keyword(s):  
New York ◽  
Tree Growth ◽  
Cell Walls ◽  
Fire Blight ◽  
Shoot Growth ◽  
New York State ◽  
Bacterial Disease ◽  
Cortical Parenchyma ◽  
Shoot Blight ◽  
Prohexadione Calcium

Fire blight, a bacterial disease of rosaceous plants caused by Erwinia amylovora, is one of the most important diseases affecting commercial apple production worldwide. Antibiotics, applied at bloom to protect against blossom infection, are the most effective means of management but raise concern due to the potential for antibiotic resistance in both the pathogen population and nontarget organisms. In addition, most fire blight outbreaks in New York State often emerge in late June to July as shoot blight, calling into question the role of blossom infections and the antibiotic applications made to manage them. Prohexadione-calcium (PhCa) is a gibberellic acid inhibitor used post-bloom to control shoot vigor and to manage shoot blight. However, the magnitude of shoot blight management is directly related to the suppression of shoot growth, which is undesirable, especially in young orchards during establishment years. PhCa is believed to control shoot blight by thickening cell walls in cortical parenchyma, preventing invasion of host tissues by E. amylovora. We hypothesize that PhCa applied pre-bloom could similarly prevent invasion of blossom pedicels following infection, leading to reduced disease incidence. We evaluated novel pre-bloom PhCa programs for their effects on disease management (blossom and shoot blight) as well as their impact on shoot growth for three years in a mature ‘Gala’ orchard in New York. In all three years of the study, all PhCa programs resulted in less than 27% incidence (71% control) of blossom blight and less than 13% incidence (77% control) of shoot blight with minimal effect on tree growth. Inclusion of a biopesticide during bloom further reduced the incidence of blossom blight in one year of three. Using light microscopy, we found that cell walls in the cortical parenchyma of fruitlet pedicels on trees receiving pre-bloom PhCa applications were significantly thicker than those of untreated trees 40 days after full bloom and inoculation. Overall, we found that pre-bloom applications of PhCa had utility in reducing blossom blight and shoot blight with minimal impacts on tree growth. These pre-bloom programs would fit with standard production practices and may contribute toward the development of fire blight management programs without the use of antibiotics.

scholarly journals Prevalence of Streptomycin-Resistant Erwinia amylovora in New York Apple Orchards

Plant Disease ◽  
2016 ◽  
Vol 100 (4) ◽  
pp. 802-809 ◽  
Author(s):  
K. A. Tancos ◽  
S. Villani ◽  
S. Kuehne ◽  
E. Borejsza-Wysocka ◽  
D. Breth ◽  
...  
Keyword(s):  
United States ◽  
New York ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
The United States ◽  
Streptomycin Resistance ◽  
Apple Orchards ◽  
Wayne County ◽  
The Past ◽  
Shoot Blight

Resistance to streptomycin in Erwinia amylovora was first observed in the United States in the 1970s but was not found in New York until 2002, when streptomycin-resistant (SmR) E. amylovora was isolated from orchards in Wayne County. From 2011 to 2014, in total, 591 fire blight samples representing shoot blight, blossom blight, and rootstock blight were collected from 80 apple orchards in New York. From these samples, 1,280 isolates of E. amylovora were obtained and assessed for streptomycin resistance. In all, 34 SmR E. amylovora isolates were obtained from 19 individual commercial orchards. The majority of the resistant isolates were collected from orchards in Wayne County, and the remaining were from other counties in western New York. Of the 34 resistant isolates, 32 contained the streptomycin resistance gene pair strA/strB in the transposon Tn5393 on the nonconjugative plasmid pEA29. This determinant of streptomycin resistance has only been found in SmR E. amylovora isolates from Michigan and the SmR E. amylovora isolates discovered in Wayne County, NY in 2002. Currently, our data indicate that SmR E. amylovora is restricted to counties in western New York and is concentrated in the county with the original outbreak. Because the resistance is primarily present on the nonconjugative plasmid, it is possible that SmR has been present in Wayne County since the introduction in 2002, and has spread within and out of Wayne County to additional commercial growers over the past decade. However, research is still needed to provide in-depth understanding of the origin and spread of the newly discovered SmR E. amylovora to reduce the spread of streptomycin resistance into other apple-growing regions, and address the sustainability of streptomycin use for fire blight management in New York.

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.

scholarly journals A Severe Outbreak of Fire Blight in Woody Ornamental Rosaceae Plants in North Florida and South Georgia

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1153-1153 ◽  
Author(s):  
M. T. Momol ◽  
E. A. Momol ◽  
W. Dankers
Keyword(s):  
Fire Blight ◽  
Acid Methyl Ester ◽  
Control Measures ◽  
Preventive Control ◽  
Susceptible Host ◽  
South Georgia ◽  
Pyrus Calleryana ◽  
Consumer Services ◽  
Shoot Blight ◽  
Rain Events

Woody ornamentals including ‘Bradford’ and ‘Aristocrat’ pears (Pyrus calleryana), Indian hawthorn (Rhaphiolepis sp.), and cotoneaster (Cotoneaster spp.) developed blossom and shoot blight symptoms suggestive of fire blight caused by Erwinia amylovora. Disease was observed in several counties in north Florida and south Georgia and samples were sent to Florida Extension Plant Diagnostic Clinic-Quincy (FEPDC-Q). The incidences in individual ‘Bradford’ pear were as high as 30 to 40 strikes per tree. This level of severe E. amylovora infections on ‘Bradford’ pear has not been seen in Florida for the last 10 years based on FEPDC-Q data. Symptomatic plants first appeared in the landscape and nurseries around the first week of April 2000 in the following counties: Bay, Holmes, Washington, Gadsden, Leon, Jefferson (north Florida), and Decatur (south Georgia). Severely infected ‘Bradford’ pear trees were also observed in Georgia cities of Cairo, Thomasville, Moultrie, and Tifton. The presence of E. amylovora in samples was verified by pEA29-polymerase chain reaction (PCR) (2,4), fatty acid methyl ester analysis (MIDI, Newark, DE), and colony type on semi-selective modified Miller-Schroth (MMS) medium (3). Of the 16 samples tested by PCR, E. amylovora was present in all. Actively growing shoots of Cotoneaster salicifolius (a susceptible host) were inoculated with a bacterium isolated from ‘Bradford’ pears that was identified as E. amylovora by PCR. Dark brown necrotic tissues with typical fire blight appearance developed within 10 days. E. amylovora was reisolated on MMS medium from inoculated shoot tissues of C. salicifolius and confirmed by PCR. The presence of E. amylovora from ornamental pears, Indian hawthorn, and cotoneasters was previously reported in Florida (1). Cool spring temperatures in the Florida panhandle and several rain events during the bloom period may have stimulated the severe outbreak of fire blight. This severe outbreak highlights the importance of using a forecasting model such as Maryblyt 4.3 to predict unexpected infection periods so that preventive control measures can be taken. References: (1) S. A. Alfieri, Jr. et al. Florida Department of Agriculture and Consumer Services, Bulletin No. 14, 1994. (2) S. Bereswill et al. Appl. Environ. Microbiol. 58:3522, 1992. (3) W. Brulez and W. Zeller. Acta Hortic. 117:37, 1981. (4) M. T. Momol et al. Plant Dis. 82:646, 1998.

scholarly journals The Effect of Repeat Annual Applications of Prohexadione–calcium on Fruit Set, Return Bloom, and Fruit Size of Apples

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 376-379 ◽  
Author(s):  
Duane W. Greene
Keyword(s):  
Vegetative Growth ◽  
Fire Blight ◽  
Fruit Set ◽  
Fruit Size ◽  
Application Rate ◽  
Fruit Weight ◽  
Initial Application ◽  
Shoot Blight ◽  
Return Bloom ◽  
Prohexadione Calcium

Prohexadione–calcium (ProCa) is used routinely in orchards to control vegetative growth and to reduce the shoot blight phase of fire blight. This communication reports on multiple-year applications of ProCa with special emphasis on treatment effects on fruit set, fruit size, and return bloom. Increased fruit set was confirmed from high rates of ProCa above 125 mg·L−1. The increase in fruit set was attributed primarily to a reduction of abscission during June drop rather than an increase in initial set. ProCa decreased fruit weight in some instances. Part of this reduction could be attributed to increased fruit set. However, the large reduction in fruit weight at harvest could only be explained by a direct effect of ProCa when used at high rates. When ProCa was applied as a concentrate spray at 250 mg·L−1, terminal growth was reduced comparable to the application made as a tree row volume dilute spray (1×). However, fruit set was increased when the spray volume in which ProCa was delivered was reduced to 4×. A range of ProCa rates was used on ‘Mutsu’. An initial application rate of 42 mg·L−1 followed by similar subsequent rates controlled growth comparably to higher initial and total rates, yet low rates had no effect on fruit weight or return bloom. Low rates of ProCa appear to be effective at controlling vegetative growth yet appear to have minimal side effects. High rates, especially those intended to reduce fire blight, come with the risk of increased fruit set and reduced fruit size and return bloom.

Importance of pear-tissue injury to infection by Erwinia amylovora and control with streptomycin

1972 ◽  
Vol 18 (6) ◽  
pp. 893-900 ◽  
Author(s):  
T. van der Zwet ◽  
H. L. Keil
Keyword(s):  
Laboratory Experiments ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Tissue Injury ◽  
Time Intervals ◽  
Inoculum Concentration ◽  
Sand Blasting ◽  
Shoot Blight ◽  
Excellent Control ◽  
And Control

Greenhouse, orchard, and laboratory experiments have shown the significance of pear shoot and fruit injury to infection by Erwinia amylovora. Bartlett trees injured by sand blasting and then spray-inoculated in the greenhouse were infected predominantly through leaf petioles. Blight development was more severe when inoculated trees were incubated in the moist chamber than on the greenhouse bench and when inoculated within 24 h after injury than after longer time intervals. Streptomycin provided satisfactory blight control of injured trees when applied within 6 h after inoculation, while uninjured trees were protected for 4 days. Excellent control was obtained when streptomycin was applied within 24 h after injury and inoculation, when preceded by a protective streptomycin spray. All injured Bartlett fruit on orchard trees dipped in E. amylovora inoculum at time of wounding blighted, while 70% of those bruised 2 days before or after inoculation became infected, regardless of streptomycin application. Dip-inoculated, streptomycin-treated fruit bruised with breakage of the skin showed 5 times more blighted fruit than when the skin remained unbroken. Orchard observations on four pear cultivars under severe blight conditions revealed that 62% of the trees exhibited both shoot and fruit blight, 8% only shoot blight, and 17% only fruit blight. Moonglow cultivar was the most resistant to fire blight and showed the lowest percent infected fruit. In the laboratory, punctured and inoculated fruit of all cultivars blighted but uninjured DeVoe fruit did not blight regardless of inoculum concentration.

scholarly journals Fire blight in Hungary between 1996 and 2003

2004 ◽  
Vol 10 (2) ◽  
Author(s):  
Zs. Mike
Keyword(s):  
Soil Conservation ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Plant Protection ◽  
Middle Part ◽  
Plant Cultivation ◽  
Pome Fruits ◽  
Shoot Blight ◽  
North Western ◽  
Modern Technologies

Shoot blight of pome fruits caused by Erwinia amylovora, i.e. fire blight, is present in numerous countries of Europe. The disease must have entered into Hungary in the middle of the 1990's and it was first noted and, respectively, identified in 1996 (Bacs-Kiskun county). The losses caused by the pathogen appeared — in orchards and scattered sites of production — in four counties, namely Bacs-Kiskun, Baranya, Bekes and Csongrad at the beginning. From June 1996, a process of eliminating infected parts started in the course of a large action performed under the control of the Department of Plant Protection and Agro-Environmental Economy of the Ministry of Agriculture, under the direction of the plant protection inspectors of the then existing Stations of Plant Health and Soil Conservation. The 'operation' against the disease commenced by cutting back out the infected parts of the canopy and, grubbing them out, respectively. As for the spread of the pathogen (1996-1998) it could be observed that the disease entered into Hungary from the south, south-east and then it also spread into the middle part of the country. As a result of adequate official action and efforts as well as of adequate chemical and antibiotic treatments, moreover because of the introduction of more modern technologies of plant cultivation and those of plant protection it can be reported on that the pathogen hardly appears or does not occur at all on the northern, north-western part of the country. The infection also appears mainly on the parts east of the Danube. Cultivars less susceptible or non-susceptible to the disease are planted in recently established orchards what is also a considerable factor in respect of preventing spread of the pathogen.

scholarly journals A New Approach to Fire Blight Control: Mycorrhiza

HortScience ◽  
2006 ◽  
Vol 41 (5) ◽  
pp. 1309-1312 ◽  
Author(s):  
Kubilay Kurtulus Bastas ◽  
Aysen Akay ◽  
Salih Maden
Keyword(s):  
Fire Blight ◽  
Shoot Growth ◽  
Glomus Intraradices ◽  
Erwinia Amylovora ◽  
New Approach ◽  
Vesicular Arbuscular ◽  
Pome Fruits ◽  
Shoot Blight ◽  
Apple Cultivars ◽  
And Control

The first outbreak of fire blight incited by Erwinia amylovora (Burr.) Winslow et al. occurred on pome fruits in Turkey in 1985, and it is now one of the most serious diseases of pear, apple, quince, and loquat (Oktem and Benlioglu, 1988). In this study, experiments were conducted in Konya Province to evaluate the efficacy of Glomus intraradices Schenck & Smith vesicular–arbuscular mycorrhiza (VAM) and bactericides for control of the shoot blight phase of fire blight and control of shoot growth on the different apple cultivars (Gala, Red Elstar, Pinova, Jonagored) on M9 rootstock in 2002 to 2003. Streptomycin provided 84.38% to 95.24% and 85.28% to 89.97% disease control in 2002 and 2003, respectively. Copper complex was not so effective against shoot blight phase of the disease, and it reduced disease by 16.18% to 27.75% and 14.48% to 19.06% in 2002 and 2003, respectively. Results of VAM application were encouraging, indicating a reduction of fire blight by Glomus intraradices of between 9.7% and 50.5% in 2002 and between 23.9% and 48.4% in 2003, respectively.

scholarly journals Evaluation of host resistance inducers and conventional products for fire blight management in loquat and quince

2008 ◽  
Vol 88 (3) ◽  
pp. 93-101 ◽  
Author(s):  
Kubilay Kurtulus Bastas ◽  
Salih Maden
Keyword(s):  
Humic Acid ◽  
Disease Severity ◽  
Fire Blight ◽  
Fruit Trees ◽  
Pome Fruit ◽  
Copper Salts ◽  
Harpin Protein ◽  
Shoot Blight ◽  
Resistance Inducers ◽  
Blight Disease

Abstract Fire blight disease is one of the most destructive diseases of pome fruits. Due to the lack of effective, non-phytotoxic and publicly acceptable materials for controlling fire blight in pome fruit trees, new strategies to manage Erwinia amylovora fire blight are being sought. The resistance-inducing compounds prohexadione-Ca, harpin protein and benzothiadiazole (acibenzolar-S-methyl), the fertilizer humic acid, the bactericides streptomycin and copper salts, and combinations of copper with chemicals were evaluated for their ability to control fire blight on quince and loquat cultivars. Prohexadione-Ca was applied at a rate of 125 mg L-1 at two shoot lengths (6-12 cm and 15-20 cm), while benzothiadiazole + metalaxyl (135 mg L-1) and harpin (50 mg L-1) were applied when the shoots measured between 15-20 cm, and again at 30-35 cm. On loquat cv. Cukurgobek, benzothiadiazole + metalaxyl showed about 60% effectiveness. The addition of copper salts reduced the effectiveness of benzothiadiazole + metalaxyl. On quince cultivars, streptomycin (P ≤ 0.05) was the most effective treatment during both years, followed by the harpin protein alone and in combination with copper salts. Prohexadione-Ca, benzothiadiazole + metalaxyl, and harpin protein applications reduced disease severity on inoculated shoots compared with copper and untreated controls. Prohexadione-Ca reduced both shoot length and shoot blight on the two hosts. Humic acid applications were ineffective in controlling fire blight on loquat and quince cultivars. Quince cv. Eşme showed lower disease severity than cv. Ekmek (P ≤ 0.05). The use of resistance-inducing substances during the early phase of shoot growth may offer a means of managing the shoot blight phase of fire blight disease on quince and loquat.

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