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United States Department of Agriculture

Agricultural Research Service

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Location: Southern Horticultural Research

2013 Annual Report

1a. Objectives (from AD-416):
Develop strategies for controlling insects that are problematic in nursery settings (e.g., fire ants, tree borers, Japanese beetles) in the southeastern United States and/or develop strategies for implementation of low-residual pesticides.

1b. Approach (from AD-416):
1) Elucidate the physiological chemical ecology of fire ants and other insects that are problematic in greenhouses, container pads, fields, and other environs suitable for growing ornamental crops. 2) Develop spray strategies to best use pesticides (specifically fungicides) that have low residual acitivity.

3. Progress Report:
This serves as the final report. To establish new, non-chemical control methods for fire ant (FA) in Tennessee, FA workers were collected and shipped to USDA-APHIS for exposure to FA Pseudacteon parasitoid flies. The principal fly species was P. obtusus, but smaller and medium FA workers were also exposed to P. tricuspis and P. curvatus). Parasitized ants were re-released in the wild in Franklin Co. during Sept. 2011 and Sequatchie Co. during July 2012 and 2013.To date, only P. curvatus flies have been recovered at the Franklin and Sequatchie sites. The sites has been checked every year since release for fly establishment and is continuing to be monitored, since it could require several years to detect flies following new population founding. The P. obtusus species is known to attack FA along foraging trails, so in addition to mound disturbance to attract Pseudacteon flies in general, foraging-trail-traps were also evaluated at the release sites to enhance the likelihood of detecting P. obtusus. Foraging-trail-traps consisted of a food bait to recruit FA workers placed near a sticky trap to capture any flies that might respond to the foraging workers. The sticky cards have successfully recovered P. curvatus at the release sites, but not P. obtusus or P. tricuspis. Aspirations of flies near disturbed FA mounds have also only produced P. curvatus collections to date. New techniques and results from applied research were provided to nursery growers, landscapers, regulatory, and other public stakeholders at multiple educational venues. An estimated 5,090 stakeholders were educated about invasive insect issues by our program during the 2011 to 2013 period. In addition, a film documentary about Pseudacteon flies attacking FA for the BBC program, Nature’s Weirdest, was also filmed during the period with the potential to reach thousands of stakeholders when released publicly. Another objective of this project is to identify diseases that impact nursery production system and develop disease management strategies. Research on control agents focused on methods of application with biological control bacteria and fungi. Four agents were identified two fungi and two bacteria. Powdery mildew control in dogwood seedlings by drenching of seedlings with the bacteria and fungi was as effective as the standard foliar spray. Subsequent plant tissue analysis confirmed the presence of two bacteria and one of the fungi in the plant tissue. Also, two bacteria were found to be effective in controlling root rot and boosting plant growth. Other research on diseases of economic concern to growers focused on cherry leaf spot of flowering cherry. Identification of effective control methods and strategies for efficacious application of fungicides and the timing of disease establishment were determined. Four fungicides, two newer formulations and two older copper-based fungicides, were evaluated individually and in rotations; they were all highly effective in controlling cherry leaf spots, shot hole and defoliation. Previously infected plants developed infection in greenhouse environment where they were protected from airborne sources of infection. Results confirmed that cherry leaf spot overwinters in dormant buds and is the source of infection in spring. Impact of research findings is on growers who are now able to control cherry leaf spot by proper timing of fungicide applications and by avoiding plant propagation from previously infected plants. Effective control of cherry leaf spot in flowering cherry was evident in the increased plant growth and market value. Producers experienced first hand benefit of results and continue to play an important role in dissemination of research results to other growers in the southeastern states where these plants are markete

4. Accomplishments

Last Modified: 06/24/2017
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