Recipient Organization
FLORIDA A&M UNIVERSITY
(N/A)
TALLAHASSEE,FL 32307
Performing Department
Cooperative Agric Res Programs
Non Technical Summary
Invasive species constitute serious problems in the forest ecosystems of Florida and other Gulf Coast States. According to two lead Florida state agencies, the average annual cost of managing exotic species (plants and animals) in Florida is estimated at $690 million. One invasive plant species, cogongrass (Imperata cylindrica), costs the state about $20 million annually. State agencies and private landowners rely heavily on herbicides for cogongrass control − spending millions of dollars annually on this management strategy. After herbicide treatment, cogongrass will rapidly reinfest. This project seeks to discover desirable native grasses that can be used to vegetate herbicide-treated sites. The benefits of this project to Florida will be in reducing the financial burden of managing this invasive species, in enhancing natural areas, recreational areas, interstate highways, and other rights-of-way, and restoring biodiversity to many fragile ecosystems currently impacted by cogongrass. Overall, it will provide a management strategy for the biological control (plant:plant perspective) of an invasive species by using native plant species. The study fits well into the goals of effectively protecting our forests and natural resources against destructive agents. The second goal of this project concerns the management of a non-native insect, the redbay ambrosia beetle (Xyleborus glabratus), which has been recently introduced into forests of the southeastern United States. Damage is caused by an associated fungus which can cause the death of an infected plant in as little as eight weeks. Redbay, sassafras, and potentially avocado are threatened. The beetle and its fungus have spread rapidly and created an epidemic through natural spread and accidental introductions. In spite of recent research, there are no control measures and very little is known about its biology and its interactions with various host trees. The objectives of this project are to learn more of the biology and population dynamics of the beetle, to collect and characterize the pathogenic fungi carried by the beetle, to collect and characterize associated fungal pathogens which might be useful in control, and ultimately to develop an environmentally friendly and sustainable pest management strategy. The work will be done at Florida A&M University in collaboration with the USDA Forest Service, USDA/ARS, and the Florida Department of Agriculture & Consumer Affairs (Forest Service; Division of Plant Industry).
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
This project is concerned with protection of Florida forests against two invasive species using biological control. The first, cogongrass, is a severe exotic plant problem and is now ranked as the 7th worst invasive plant species in Florida in spite of large investments by public and private organizations and individual landowners. There is a need for in situ studies on management of the invasive plant. The goals of this project are to: 1) Evaluate the performance of four native grass species for the vegetation of imazapyr-treated plots in cogongrass infested forest lands in Florida; 2) Determine the most effective time for introducing planting materials into an imazapyr-treated southern pine forest soil environment; 3) Identify and select native grass species plant genotypes with high levels of tolerance to imazapyr plots; and 4) Provide the extent to which vegetational species will continue to prevent the reinvasion of forest lands by cogongrass. Outcomes will provide an integrated approach to managing this invasive species, help to restore soil structure, and enhance native microbial and beneficial insect populations. Successful outcomes will provide soil cover leading to restoration of wildlife species while reducing or eliminating herbicide use. Overall, this project will provide a management strategy for the biological control (plant:plant perspective) of an invasive plant. The second set of objectives concerns the recently introduced invasive redbay ambrosia beetle which carries a fungus that threatens native vegetation in forests of the Southeast. The overall goal is to develop an integrated approach to control this beetle, and specific objectives include: 1) Study of biology and dynamics of populations of the redbay ambrosia beetle; 2) Collection and identification of field collected fungal pathogens from live and dead ambrosia beetles and its symbiotic fungi using DNA fingerprinting techniques; 3) Evaluation of the pathogenicity and virulence of biocontrol fungi against the redbay ambrosia beetle as well as the most promising fungal pathogens isolated from field-collected beetles; and 4) Development of an environmental friendly and sustainable management strategy. Unique to this project is the attempt to isolate existing fungal pathogens which might compete with the fungal pathogens carried by the beetle, or possibly provide direct control of the beetle as part of a management strategy. Results should provide more information on basic biology and distribution of the beetle in the search for new approaches and natural control agents to be used in management or control. The project represents collaborative efforts between faculty in Agriculture, Biology, and Environmental Sciences at Florida A&M University, and will support two graduate students in original research with results leading to improved management of forest pests. It will also strengthen existing partnerships and cooperative efforts between the University and other state and federal agencies concerned with invasive species. At the conclusion of this project, strong cooperative linkages will serve as useful and reliable foundations for future ventures.
Project Methods
The evaluation of plant genotypes for vegetation of cogongrass infested ecosystems will be conducted at four forest locations in Florida where cogongrass now forms monocultures. Native grass species (bluestem broomsedge, citrus maidencane, switch grass and hairy awn muhly grass) will be used for a nested factorial design to include: herbicide application time (spring and fall); native grass species; and time of planting following herbicide application. Treatments (mowing vs. herbicide application) will be randomly assigned in three replications; the herbicide imazapyr (5%) will be used for all replications. For the spring application, plots will be treated with herbicide in March and native grasses from the greenhouse will be transplanted to these fields in May followed later by transplanting in June and July. For the fall application, the infested understory will be treated in October and native grasses will be transplanted at monthly intervals starting the following March. In each location, a 120 ft sq area will be selected for the field layout. Within each area, square plots (9 ft on a side) will be used for each planting of the 4 native species; another trial plot in each series will serve as a control; and the remaining area will be left unplanted for ecologically recruited volunteer plants. This will give 45 trial plots of 81 sq ft each for study at each location. Data to be collected are initial plant survival and, later, data on growth and performance: height, diameter, shoot vigor ratings, light interception (mols. per sq ft), shoot canopy, and herbage biomass. Biomass will be determined by use of a disc meter set at low, medium and high. Ten random samples will be taken for each replication and data will be analyzed using ANOVA. Data on genotypic identification of native plant species will also be analyzed using combined ANOVA. These genotypes will be flagged, collected and made available for in vivo and in vitro rapid multiplication methodologies. For study of the redbay ambrosia beetle, field collections will be made from established populations in infested trees. Rearing techniques will use artificial diets; beetles could also be reared in logs at infested sites. Live beetles and cadavers will be collected, surface-sterilized and plated to investigate potential fungal pathogens. Fungal symbionts will be isolated and incubated on standard media and identified using molecular genetic techniques to determine the different isolates of symbiotic fungi. We will also investigate competition between the fungal symbionts and pathenogenic fungi such as Metarhizium, Beauveria, Paecelomyces, and other isolates. For field studies of efficacy of fungal pathogens, 4 blocks of host trees will be established, each with 10 similar trees. Statistical analyses of concentration-mortality data will be subjected to probit analysis to obtain the lethal doses. Based on susceptibility of redbay ambrosia beetle to fungal pathogens, a potential pest management strategy will be developed.