Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/6361
Title: Potential of a pathogen, Mycoleptodiscus terrestris, as a biocontrol agent for the management of Myriophyllum spicatum in Lake Guntersville Reservoir
Authors: Shearer, Judy F. (Judy Fredrickson)
Keywords: Biocontrol
Biological control
Eurasian watermilfoil
Fungal pathogen
Fungi
Mycoleptodiscus terrestris
Myriophyllum spicatum
Aquatic Plant Control Research Program (U.S.)
Publisher: U.S. Army Engineer Waterways Experiment Station
Series/Report no.: Technical Report (Aquatic Plant Control Research Program (U.S.)) ; no.Technical Report A-96-4
Abstract: The use of classical biocontrol techniques for milfoil management was not a viable option when the Joint Agency Guntersville Project sponsored by the Tennessee Valley Authority and Headquarters, U.S. Army Corps of Engineers began. No host specific insects had been approved for release, and overseas searches for pathogens had not yet been initiated. A microbial biocontrol strategy, the inundative method, utilizing an endemic plant pathogen, Mycoleptodiscus terrestris (Gerd.) Ostazeski (Mt), known to be a parasite on milfoil, was proposed. Introduction of microbes for biological control purposes against nuisance pest populations is strictly regulated by individual State agencies and two Federal agencies, including the U.S. Environmental Protection Agency and Agriculture Protection Health Inspection Service. The use of a pathogen that is known to be endemic within a State lessens the fear associated with introducing a microbe into a new area. Surveys were conducted on Lake Guntersville Reservoir to provide documentation on pathogens of milfoil to faci litate the permitting process from State and Federal agencies. Thirty-two fungal species were isolated from milfoil stem tissue collected at Mud Creek, North Sauty, and Comer Bridge sites. Mycoleptodiscus terrestris was isolated from 29 of the 30 plant samples collected on Lake Guntersville. In addition to Mt, pathogenic species from the fungal genera, Pythium, Curvularia, Cylindrocarpon, and Macrophoma, were also collected. A formulation of the endemic pathogen Mt had been developed by EcoScience Inc., Worchester, MA. The mycelium of the fungus was grown in large fermentors, incorporated into a calcium alginate matrix, and extruded as strings approximately 2 by 20 mm. The formulated fungus or mycoherbicide was registered under the trade name Aqua-Fyte. Evaluation of the mycoherbicide under field conditions was undertaken in the summer of 1992. Aqua-Fyte was ineffective in reducing aboveground biomass of Eurasian watermilfoil under natural conditions in the field. Poor performance of the mycoherbicide was thought to be due to formulation problems rather than biological, chemical, or physical factors encountered in the field. The formulated strings did not appear to adhere to plant surfaces at enough contact points for the fungus to become well established in plant tissue and induce a disease epidemic. Because Aqua-Fyte did not produce the desired results in the field, the fungal component of the formulation needed to be reevaluated for its effectiveness as a biocontrol agent for milfoil. The mycelium of Mt applied as an aqueous medium to milfoil in laboratory and greenhouse experiments successfully produced disease symptoms in stem and leaf tissue and reduced aboveground biomass. However, when applied to milfoil in the field, the mycelium failed to produce a disease epidemic. Applying the fungus in mycelial form in the field has its drawbacks because there is immediate dissipation and dilution when adding the fungus as a liquified matrix to an aqueous medium. Before the inundative strategy of biocontrol can successfully be applied to management of submersed aquatic plants, research must focus on the development of carrier compounds that will adhere to the target plant at multiple points for long periods of time. Further pathogen research must address methods to enhance the fungal component through strain improvement, fermentation technology, and drying.
Description: Technical Report
Gov't Doc #: Technical Report A-96-4
Rights: Approved for public release; distribution is unlimited
URI: http://hdl.handle.net/11681/6361
Appears in Collections:Technical Report

Files in This Item:
File Description SizeFormat 
TR-A-96-4.pdfTechnical Report A-96-44.64 MBAdobe PDFThumbnail
View/Open