Status of streptomycin-resistant Erwinia amylovora in Illinois apple orchards and evaluation of alternative compounds to manage fire blight disease

Illinois apple growers produce approximately 17,963 metric tons of apples annually. Fire blight disease, caused by the bacterium Erwinia amylovora, is a serious threat to apple production in Illinois and other Midwestern states. Streptomycin has been the most effective chemical for control of fire blight of pome fruits in Illinois, as well as nationwide. In 2008 and 2009, severe fire blight occurred in Illinois apple orchards, leading to speculation that streptomycin-resistant strains of E. amylovora might be present in some orchards. Statewide surveys were conducted in 2010, 2011, and 2012, and 117, 129, and 170, E. amylovora isolates were collected each year, respectively, from 19 counties. None of the 416 E. amylovora isolates tested were streptomycin-resistant at 50 mg/L. However, nine non-E. amylovora isolates contained both a strA-strB streptomycin-resistance gene and IS1133 on transposon Tn5393, which could be a potential source of streptomycin-resistance for Illinois E. amylovora in the future. E. amylovora isolates collected in this survey also were tested for copper resistance. All 84 isolates evaluated were sensitive to 0.16 mM copper sulfate, indicating copper compounds are still effective for management of fire blight in Illinois. During 2011-2012, laboratory and field trials were conducted to evaluate efficacy of streptomycin-alternatives (oxytetracycline, kasugamycin, Bacillus subtilis, Pseudomonas fluorescens, and prohexadione calcium) for control of fire blight. Kasugamycin compounds (Kasumin 2L and ARY-4016-06) significantly (P<0.10) reduced blossom infection in the orchard. In 2012, effectiveness of growth regulator prohexadione calcium (Apogee 27.5DF) in combination with streptomycin-alternatives was also evaluated. An Apogee x Kasumin 2L interaction significantly (P<0.0009) reduced shoot blight infection. This interaction was not observed with ARY-4016-06 or any other treatment.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2013

Author dc:creator

• Jurgens, Andrew

Contributors dc:contributor

• Babadoost, Mohammad

• apple
• fire blight
• Erwinia amylovora
• streptomycin
• resistance
• kasugamycin
• copper
• biological control
• oxytetracyline

Statement dc:rights

• Copyright 2012 Andrew Jurgens

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/42178

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/42178