Aquatic Plant Control Research Program: Field Evaluation of Microbiological Control Agents on Eurasian Watermilfoil

摘要

Control of Myriophyllum spicatum L., as previously reported, was based on the multiple effects achieved by the fungus Mycoleptodiscus terrestris and selected bacterial isolates with strong pectinolytic abilities and the capacity to exercise a hormonelike stress effect on the plants. Enriched media were adopted for growth of the fungus and bacterial inoculants. This reduced incubation time to 72 hr for the fungus and to 48 hr for the bacterium. These changes in inoculum growth procedures were reflected in the subsequent change in the pattern of M. spicatum decline after exposure to the control agents: from the appearance of isolated necrotic areas to generalized systematic decline and the ultimate disintegration of the plant. The most rapid and devastating response to the organisms grown in these new media was observed in the laboratory when the inoculated plants were maintained in jars. This reflected the sustained high concentration of the inoculum and isolation from environmental effects. The results of these initial field tests on the control of M. spicatum by the application of plant-derived microorganisms provide grounds to pursue the development of this approach as a practical control strategy.