2009 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.
Research addressing a number of plant pest issues affecting the nursery industry was conducted. New insecticide treatments for flat headed borer are being developed; this insect causes losses in some genera in the range of 20-40% annually. Testing indicates current grower treatments (i.e., chlorpyrifos trunk sprays) are ineffective. We have developed applications utilizing several systemic insecticides (imidacloprid, clothianidin, dinotefuran, and thiamethoxam) that provide up to 100% control of the insect for up to three years with a single application.
Ambrosia beetles are another concern to the nursery industry. Attacks by these insects result in nurseries having to cull large numbers of trees annually. However, attacks occur during a very small window of time, and do not follow a clear pattern, making development of treatments to thwart attacks very difficult, if not impossible. Researchers at the Nursery Research Center (NRC) have developed a new ethanol-based method to reliably induce ambrosia beetle attacks, allowing for the first time the ability to systematically test insecticide treatments to defend against this pest.
In the area of plant pathology, we continue an emphasis in disease control in flowering dogwood, continuing long term research to improve dogwood production through improved host resistance, development of biorational products, implementation of biological control methods, and improved timing of treatments. Selection for resistance has been completed for new cultivar releases in dogwood. Non-biological products such as plant oils, minerals and soaps that are effective in controlling powdery mildew have been identified and are being introduced to the industry. Exciting results have been obtained in the search for microbial organisms that effectively control mildew in dogwood, the feasibility of utilizing these organisms as pesticides is being assessed.
Research continues in a comprehensive research project to conduct field surveys to document important soil-borne pathogens and pathogens in irrigation water, streams and ponds, identify and characterize Phytophthora spp. in Tennessee soil and plant tissues, identify Verticillium, Fusarium and others pathogens and determine their incidence, hosts and economic significance, and to develop an educational tool on Phytophthora diseases for nursery growers to help them make informed decisions on disease management strategies.
In response to stakeholder concerns, an examination of a defoliation problem in Flowering Cherry led to the identification of a pathogen not previously known to occur in Tennessee. Research has been establish to identify the mode of spread, the seasonality, the correct timing of control measures, and identification of the most efficient control compounds for this disease. This project is a collaborative effort with producers; fungicide evaluation and other control strategies are being initiated immediately to help growers reduce economic losses from this disease. The ADODR or his representative meets regularly with the cooperating scientist, and these meetings include site visits.