Project Overview
Annual Reports
Commodities
- Fruits: apples, pears, general tree fruits
Practices
- Education and Training: demonstration, on-farm/ranch research
- Farm Business Management: agritourism
- Pest Management: biological control, biorational pesticides, chemical control, cultural control, field monitoring/scouting, prevention, sanitation
- Production Systems: general crop production
Proposal abstract:
More than 300 growers manage approximately 5,000 acres of apple orchards in Illinois. Illinois with a population of 13,000,000 is a huge market for apples, particularly for the rapidly growing “You Pick” operations. Fire blight, caused by the bacterium Erwinia amylovora, is a serious threat to apple production in Illinois and other Midwestern states. Apple trees are most vulnerable to fire blight infection at bloom. Streptomycin has been the most effective chemical for control of fire blight of apple and other pome fruits. However, streptomycin-resistant (SmR) E. amylovora populations have been reported from several apple growing states. Widespread and severe fire blight occurred in Illinois apple orchards in the past five years leading to speculation that SmR strains of E. amylovora may have developed in some orchards in the state. No previous study has been conducted in Illinois to determine the presence of SmR bacterium in the state. Since, streptomycin is the most effective antibiotic for control of fire blight of apple, it is necessary to identify cases of antibiotic-resistance early, before resistant strains become widely established. The main goal of this research is to determine if streptomycin-resistant E. amylovora exist in Illinois and develop alternative control measures for the pathogen. The specific objectives of this study will be to: (i) evaluate Illinois E. amylovora populations for streptomycin resistance, and (ii) evaluate streptomycin alternatives, including kasugamycin, oxytetracyline, copper compounds, and bio-control agents for management of fire blight. The results of the research will be published in the newsletters, bulletins, and websites; presented to the growers, Extension educators, and agribusiness in winter growers’ schools and summer horticulture days; and published in peer-reviewed journals such as Plant Disease and HortScience.
Project objectives from proposal:
Project Outcomes. Short term outcome of this project would be determining whether or not streptomycin-resistant (SmR) populations of Erwinia amylovora are present in Illinois apple orchards. The intermediate and long-term objectives of this study will be effective use of streptomycin and developing alternatives to streptomycin, including kasugamycin, oxytetracyline, copper compounds, and bio-control agents for management of fire blight. Results will be used to develop effective IPM strategies to avoid/delay occurrence of SmR E. amylovora in Illinois and neighboring states. Context, Background, Rationale. More than 300 growers manage approximately 5,000 acres of apple orchards in Illinois. Fire blight, caused by the bacterium E. amylovora, is a serious threat to apple production in Illinois and other Midwestern states. Illinois with a population of 13,000,000 is a huge market for apples, particularly for the rapidly growing “You Pick” operations. Fire blight is the main hindrance for satisfying the demands for local apple production. Streptomycin has been an important management tool for the control of fire blight. SmR E. amylovora populations have appeared in several apple producing states in the United States, including New York, Michigan, California, Oregon, and Washington. Widespread and severe fire blight in Illinois in the past five years, lead to speculation that SmR strains of E. amylovora are present in Illinois. Russo et al. (13) concluded that “streptomycin is the most effective antibiotic for use on apple and is likely to remain as such; therefore, it is imperative to identify cases of antibiotic resistance early, before bacterial populations become established.” Fire blight of apples has become more potentially destructive over the past twenty years, due to increases of high density plantings and preference shifting to more susceptible cultivars (1). Nationwide losses, due to fire blight and control costs, are estimated at $100 million per year (11). In 2000, a severe fire blight epidemic in southwest Michigan affected over 1,000 acres of apple orchards, killed over 250,000 trees, which resulted in an economic loss of nearly $42 million (4). Occurrence of fire blight is determined each season by weather conditions (e.g. temperature and rainfall) from bud break to petal fall and the severity of infection in previous year. E. amylovora overwinters at the edges of holdover cankers and in spring, when temperatures exceed 18.3ºC (65ºF), the bacterium rapidly multiply and becomes the source of primary inoculum (1). Rain splash, wind, and insects spread the bacteria onto the blossoms, leaves and shoots. Infection of plant tissues takes place through natural openings and wounds. Bacteria rapidly multiply, invade, and kill host tissue. Fire blight management requires a year-round integrated approach that reduces primary inoculum and prevents infection. Inoculum is reduced by removing infected cankers from the trees and copper applications at silver-tip growth stage in early spring. Copper applications, in early spring, reduce the bacterial populations oozing out of the cankers or building up on the buds before bloom (1). Apple trees are most vulnerable to fire blight infection at bloom; therefore, applications of antibiotics to prevent pathogen infection of blossoms are critical for management of fire blight. Available forecasting systems (MARYBLYT or Cougar Blight) monitor weather conditions and predict fire blight infection risk. The information enables growers to timely applications of antibiotic for control of fire blight. The main goal of this project is to determine if streptomycin-resistant E. amylovora exist in Illinois and develop alternative control measures for the pathogen. The specific objectives of this study will be to (i) evaluate Illinois E. amylovora populations for streptomycin resistance, and (ii) evaluate streptomycin alternatives, including kasugamycin, oxytetracyline, copper compounds, and bio-control agents for management of fire blight. The impact of this research on apple production in Illinois, and likely in other states, is expected to be enormous. Fire blight causes considerable yield and crop losses in Illinois and other states, particularly the Midwestern states. Thus, in order to prevent outbreaks of fire blight, determining the existence of streptomycin-resistant strains of E. amylovora is essential. Also, developing streptomycin-alternative control measures is necessary, as a single method for management of a serious disease (fire blight) of one of the most important crops (apple) is necessary.