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| States: | New York Pennsylvania cooperating |
| Investigators: | Herb S. Aldwinckle, M. Timur Momol, and John L. Norelli |
| Institutions: | NYS Agricultural Experiment Station, Cornell University, Geneva, NY Pennsylvania State University |
| Project Type: | research |
| Award*: | $99,970 |
| Term: | 36 months |
Crop: |
Apple is the most important fruit crop in the Northeast with a farm gate value of $140 million. currently most apple growers in the Northeast are replanting orchards into expensive high density systems using scion varieties and rootstocks that are very susceptible to fire blight. In New York, losses resulting from a fire blight epidemic in newly established high density orchards were estimated at $3,571 per acre (Momol et al. 1997a).
Fire blight develops in several phases, of which blossom blight is the most studied and best understood. Satisfactory control of blossom blight largely depends on several streptomycin applications during bloom times according to the Maryblyt™ forecasting program. By contrast to blossom blight, the shoot and rootstock phases of fire blight are not well understood and lack adequate control measures. This research project will use several strategies to develop integrated management of the shoot and rootstock phases of fire blight in high density apple orchards.
Objective 1. Determine the effectiveness of SAR inducers, growth regulator, and nutrients for management of shoot and rootstock phase of fire blight.
Objective 2. Determine the epidemiology of the rootstock phase of fire blight.
Objective 3. Identify fire blight-resistant apple scion and rootstock varieties derived from breeding and/or genetic engineering, and incorporate their use into an integrated management program for fire blight control.
The proposed research will be carried out by a team of plant pathologists and horticulturists, in both New York and Pennsylvania, and will include the involvement of extension personnel to insure that the results will be readily implemented in commercial fruit farms. Dr. Herb Aldwinckle's research team has extensive experience in several aspects of fire blight research, especially in the study and development of host resistance.
The results of the investigation will be presented orally or by poster at grower and extension educator meetings, in bulletins and trade journal and county extension newsletter articles for growers, and in scientific format for the use of IPM educators and researchers. This work will produce economic, practical and effective management of these economically important phases of fire blight on apple that are impossible to control at present. Our proposal supports the national goal of having 75% of US agriculture under IPM by the year 2000, and will enhance the sustainability of apple production in the Northeast Region.
Objective 1. Determine the effectiveness of SAR inducers, growth regulator, and nutrients for management of shoot and rootstock blight in apple orchards.
Since no recommended measures are currently available for managing the shoot and rootstock phases of fire blight (streptomycin is ineffective and coppers can not be used on trees with fresh market fruit), several tactics for reducing the incidence and severity of shoot blight will be evaluated. Reduction of shoot blight is expected to have direct beneficial effects in reducing rootstock blight. The proposed tactics fall into two categories a) Potential inducers of systemic acquired resistance (SAR) in apple: Actigard, harpin and EOY, and b) Treatment that will alter the physiology of the apple to make it less susceptible to fire blight: growth regulators, and modified nutrient management. Application of materials and nutrient regimes will be applied to trees, which will be artificially inoculated at appropriate times, and then evaluated for incidence and severity of infection. Products and nutrient management that reduce disease severity will be integrated into recommendations for management of fire blight on apple.
Objective 2. Determine the epidemiology of the rootstock phase of fire blight.
There are 3 aspects of the timing of rootstock infection that will be considered: determining if rootstock infection results from current season scion infection or from infections that occurred in previous seasons, determining if young bearing trees are more susceptible to rootstock blight than nonbearing trees, and determining if rootstock infections are more likely to result from early or late season scion infections. Knowing if scion infection results in rootstock infection in the same season, in future growing seasons, or both, will be important in understanding the epidemiology of the disease and developing management strategies. Determining the stage of tree development when rootstock infection is most likely to occur, with respect to both tree age and phenology, will allow us to target management strategies at specific times in the life of the orchard and during the growing season.
Objective 3. Identify fire blight-resistant apple scion and rootstock varieties derived from breeding and/or genetic engineering, and incorporate their use into an integrated management program for fire blight control.
Fire blight-resistant apple rootstocks, bred at Cornell-Geneva and recently released for commercial sale or in the final stages of selection, will be evaluated at several locations in New York and Pennsylvania for both resistance to fire blight and horticultural performance. The rootstocks will be evaluated for their resistance following direct inoculation in Pennsylvania. They will also be evaluated for their resistance to infection when grown under orchard conditions with high levels of disease pressure. Small test orchard plantings at several locations will be used to evaluate the rootstocks for their productivity and horticultural performance in different soil types and environmental conditions. This information is critical to be able to make specific recommendations for grower use. In addition, commercially important apple rootstocks and scions genetically engineered for improved resistance to fire blight will be evaluated under field conditions to select material for future release.
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