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Funded Project |
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Funding Program:
Regional IPM Grants (S-RIPM) |
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Project Title:
Prescription Brown Rot Management in Peach Based on Site-Specific Fungicide Resistance Profiles in Monilinia Fructicola |
Project Directors (PDs):
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Lead State: SC Lead Organization: Clemson University |
| Research Funding: $115,000 |
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Start Date: Sep-01-2006 End Date: Aug-31-2008 |
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Pests Involved: brown rot |
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Site/Commodity: peaches |
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Area of Emphasis: fungicide resistance |
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Summary:
The recently updated Pest Management Strategic Plan for Eastern Peaches emphasizes the serious threat to the sustainability of peach production posed by fungicide resistance in Monilinia fructicola, the causal agent of brown rot. Preharvest fungicide applications are a critical component of integrated brown rot management, and three chemical groups are currently available to growers: the benzimidazoles, the demethylation inhibitors (DMIs), and the respiratory inhibitors (RIs). Benzimidazole resistance caused significant losses in the early 1980s, which subsequently led to the sole reliance on DMIs for brown rot control. As a result, DMI-resistant populations of M. fructicola have started to emerge in Georgia, causing major control failures. Consequently, usage of RI fungicides has increased, increasing the risk of resistance development to this resistance-prone fungicide class. If resistance to RIs does develop, growers will be left with no alternative for brown rot control. The goal of this project is to develop and implement tools to generate site-specific fungicide resistance profiles of M. fructicola populations in order to make intelligent choices about the most suitable pre-harvest fungicide program for a given orchard. Specific objectives are to (i) develop a rapid and simple technique to estimate resistance levels to benzimidazoles, DMIs, and RIs that can be used by county agents and growers; (ii) conduct local and regional resistance monitoring in Georgia and South Carolina; and (iii) develop and evaluate resistance management strategies based on results from on-site fungicide resistance monitoring. This proposal addresses both future directions and focus directions of the National IPM Roadmap.
Objectives: Objective 1. It is likely that benzimidazole and DMI fungicide resistance is not omnipresent in the Southeast. Therefore growers will benefit from determining on-site resistance profiles in local populations of M. fructicola. With this information, they will be able to implement effective and site-specific brown rot disease management, which will be a critical component of a future improved integrated brown rot management program. In this objective we will evaluate and fine-tune a simple method to monitor resistance in M. fructicola populations. We will make this method available to growers in the proposed version or a simplified version, depending on the experience gained throughout the two experimental years. Objective 2. It is unknown what impact fungicide programs typically used by growers have on resistance development in orchard populations of M. fructicola. In this objective we will address this need by monitoring resistance levels in all major peach production areas in South Carolina and Georgia over time. This will allow us to establish a baseline resistance profile for southeastern M. fructicola populations, which will serve as a reference for future analyses. Also, we will learn how resistance in populations will shift depending on what program is implemented. This information is critical for the future design of fungicide resistance management strategies. Moreover, conducting this work on grower farms will be extremely useful when trying to educate growers about potential resistance problems with standard fungicide programs. Objective 3. While objective 2 will establish to the response of a M. fructicola population when growers use standard spray programs, this objective will specifically address the question how DMI fungicide resistance in a M. fructicola population can be managed most effectively with the tools currently available to growers and how the pathogen population will react over time when subjected to defined fungicide programs. Here again, this information is critical for the future design of much needed fungicide resistance management strategies for commercial peach growers. |
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Final Report: |
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Results From report submitted by the PI to USDA CRIS report system PROGRESS: 2006/09 TO 2009/08 OUTPUTS: We have developed and validated a novel technique to determine fungicide resistance profiles for Monilinia fructicola populations. The technique is an agar-based assay called the lipbalm tube assay packaged as the Profile monitoring kit for monitoring location-specific sensitivity profiles. Profile was featured in several popular magazines in 2008 and 2009 (see our website www.peachdoc.com for links). It determines the sensitivity of local Monilinia populations to the three most commonly used fungicide classes (DMIs, BZIs, and QoIs) and identifies the most effective spray program for brown rot control based on location-specific resistance profiles. In addition, Profile counteracts selection of pathogen populations for fungicide resistance, making disease management and the entire operation more sustainable for the future. Profile was trademarked by the United States Patent Office via Clemson University. Below is a list of peer-reviewed papers that resulted from this work. In addition, we developed a new medium that selectively allows M. fructicola to grow while inhibiting possible contaminants of peach. This medium may be very useful in the future for kit improvement and analysis of population structure. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: The clientele benefiting from our efforts are the Southeastern Peach Fruit Producers. The service we provided increased their knowledge about fungicide resistance issues, their awareness of certain actions, and improved their ability to make science-based decisions on what they need to spray. PROJECT MODIFICATIONS: Not relevant to this project. IMPACT: 2006/09 TO 2009/08 With the help of county agents, Profile was used on a larger scale basis in commercial orchards in 2008 and 2009. More than 25 key growers participated. Monitoring results allowed grower-specific recommendations and revealed new information that will help in formulating future management strategies. For example, a commonly recommended strategy to reduce the selection of resistant populations is to rotate chemical classes. However, analysis of 25 resistance profiles from South Carolina in 2008 revealed that a rotation of DMI and QoI fungicides selects for both, DMI and QoI resistance at the same rate as the individual classes alone. This is contrary to common belief that rotation of chemical classes reduces selection of resistance. Results from 2009 indicate that Propiconazole (DMI) resistant strains of M. fructicola are well established around the peach growing areas in the Southeast. Not only that, we also found a shift towards QoI resistance in South Carolina, which needs to be considered when designing spray programs. Spray records indicate that growers still utilize DMI fungicides in this region. The sites showing a shift towards resistance to azoxystrobin were also located mostly in or near this region and similarly, QoI products were used in these instances. The use of the Profile system was instrumental in preventing producer losses in 2009, a very wet year in which brown rot developed rapidly. Future use of the kit will be equally important. PUBLICATIONS (not previously reported): 2006/09 TO 2009/08 1. Amiri, A., P. Brannen and G. Schnabel 2009. Sensitivity of Monilinia fructicola Field Isolates from South Carolina and Georgia to four respiration inhibitor fungicides. Plant Disease. Submitted for review. 2. Amiri, A., P. Brannen and G. Schnabel 2009.Validation of the Lipbalm Tube Assay for Evaluation of Fungicide Sensitivity in Field Isolates of Monilinia fructicola. Plant Health Progress, in press. 3. Amiri, A., I. J. Holb and G. Schnabel 2009. A new selective medium for the recovery and enumeration of Monilinia fructicola, M. fructigena and M. laxa from stone fruit. Phytopathology 99:1199-1208. 4. Amiri, A., Scherm, H., Brannen, P. M., and Schnabel, G. 2008. Laboratory evaluation of three rapid, agar-based assays to assess fungicide sensitivity in Monilinia fructicola. Plant Dis. 92:415-420. |
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Outcomes N/A |
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Impacts From report submitted by the PI to USDA CRIS report system With the help of county agents, Profile was used on a larger scale basis in commercial orchards in 2008 and 2009. More than 25 key growers participated. Monitoring results allowed grower-specific recommendations and revealed new information that will help in formulating future management strategies. For example, a commonly recommended strategy to reduce the selection of resistant populations is to rotate chemical classes. However, analysis of 25 resistance profiles from South Carolina in 2008 revealed that a rotation of DMI and QoI fungicides selects for both, DMI and QoI resistance at the same rate as the individual classes alone. This is contrary to common belief that rotation of chemical classes reduces selection of resistance. Results from 2009 indicate that Propiconazole (DMI) resistant strains of M. fructicola are well established around the peach growing areas in the Southeast. Not only that, we also found a shift towards QoI resistance in South Carolina, which needs to be considered when designing spray programs. Spray records indicate that growers still utilize DMI fungicides in this region. The sites showing a shift towards resistance to azoxystrobin were also located mostly in or near this region and similarly, QoI products were used in these instances. The use of the Profile system was instrumental in preventing producer losses in 2009, a very wet year in which brown rot developed rapidly. Future use of the kit will be equally important. |
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