Biological Control of Aquatic Plants with Pathogenic Fungi


Book Description

The endemic fungal plant pathogen Cercospora rodmanii was shown to have a high potential as a biocontrol agent for waterhyacinths (Eichhorniae crassipes). During this study, methods of culturing and dissemination of this fungus for biocontrol purposes were developed and the host-parasite relationship was elucidated. The fungus has been patented based on the results, and it is being developed for biological control purposes. Researchers at the U.S. Army Engineer Waterways Experiment Station will evaluate the fungus in a Large Scale Operational Management Test in Louisiana. The endemic pathogen Acremonium zonatum and the exotic rust Uredeo eichhorniae, as well as C. rodmanii, exhibit biocontrol potential for waterhyacinth. An additional exotic pathogen, Fusarium roseum 'Culmorum', shows promise for biological control of the submerged aquatic weed Hydrilla verticillata. Research with the two exotic pathogens has been slowed because of the necessity of conducting studies in quarantine.




Biological Control of Plant Pathogens


Book Description

Biological balance. The biological world. Attributes of a successful parasite. Types of biological interactions. Man, the disrupter of balance. The changing scene. Factors involved in biological control. A plant pathologist's definition of biological control. Comparative approaches to biological control of plant pathogens and insects. Applying biological control. Biological control in plant pathology. The stature of biological control of plant pathogens. Resident antagonists. Managing the biological balance. Biological control by resident organisms and introduced organisms. Host resistance. Ecological manipulation to control weed molds and pathogens of mushrooms. Approaches to biological control with antagonistic microorganisms. Selecting soil as a source of antagonists. Antagonistic populations of whole soils. Presumptive tests of antagonists in agar culture. Tests in soil. Testing mixtures of antagonists. Plant of action. Role of the pathogen in biological control. Ways the pathogen can overcome antagonism. Vulnerability during dormancy and saprophytic growth. Populations of soilborne pathogenic fungi that produce disease. Stimulation of antagonists by the pathogen. Control of nematodes by altering the sex ratio. Role of the antagonist in biological control. Biological efficiency of saprophytic organisms. Kinds of antagonists. Forms of antagonism. The ideal antagonist. Inoculation with avirulent organisms related to the pathogen. Recontamination of soil. Biological buffering by resident antagonists. Role of the host in biological control. Root dynamics. Physical and chemical features of the rhizosphere. Root exudation and the rhizosphere effect. Cropping history and the microbiological balance of soil. Plant residues. The host as a reservoir of inoculum. Decoy, trap, and inhibitory plants. Role of the physical environment in biological control. environment operative through the host and during dormancy of the pathogen. Environment operative during growth of the pathogen. Using environment for prediction. Using environment to nudge the biological balance. Integration between biological and chemical control. Biological control of pathogens of aerial parts. Microorganisms on aerial parts. Pathogens on aerial parts. Exudation to external surfaces. Natural dissemination of epiphytes. Whither biological control?. Stage in pathogen cycle to apply biological control. Agroecosystems in relation to biological control. Applying, activating, or assisting antagonists. Large-scale production of antagonists. Integrated control. Why biological control?. The role of biological control in plant pathology.




A Field Test of Selected Insects and Pathogens for Control of Waterhyacinths


Book Description

During the 1975 growing season a field experiment was begun on Lake Concordia, La., to test the potential effectiveness of selected organisms as control agents against waterhyacinths, Eichhornia crassipes (Mart.) Solms. Floating frames, each approximately 2 m square, were anchored on the lake in open water and planted with locally growing waterhyacinths. Sixty of these frames (plots) were selected for treatment with various combinations of two insects (Arzama densa Walker and Neochetina eichhorniae Warner) and two fungi (Acremonium zonatum (Sawada) Gams and Cercospora rodmanii Conway) in a random block factorial arrangement with four replications per treatment, and four frames were designated as control (no-treatment) plots. All plots were weighed at 2-week intervals throughout the growing season, flowering stalks were counted, and plant heights were measured at each weighing date. Observations were also made on insect and pathogen populations on the plots during the season. Preliminary indications are that significant reductions in the growth rate or total accumulation of waterhyacinth mass in the test plots were not achieved by any of the treatment combinations during the first season's tests, but the potential for some of the treatments to effect the desired control began to emerge during the second year.




Biological Control of Plant Pathogens


Book Description

Biological balance; What is biological control?; Biological control in plant pathology; Examples of biological control; Approaches to biological control with antagonistic microorganisms; Role of the pathogen in biological control; Role of the antagonist in biological control; Role of the host in biological control; Role of the physical environment in biological control; Biological control of pathogens of aerial parts; Whither biological control?; Why biological control?.




Microbial Control of Weeds


Book Description

It is appropriate at this time to reflect on two decades of research in biological control of weeds with fungal plant pathogens. Some remarkable events have occurred in the last 20 years that represent a flurry of activity far beyond what could reasonably have been predicted. In 1969 a special topics review article by C. L. Wilson was published in Annual Reviews of Phytopathology that examined the literature and the potential for biological control of weeds with plant pathogens. In that same year, experiments were conducted in Arkansas that determined whether a fungal plant pathogen could reduce the infestation of a single weed species in rice fields. In Florida a project was under way to determine the potential use of a soil-borne plant pathogen as a means for controlling a single weed species in citrus groves. Work in Australia was published that described experiments that sought to determine whether a pathogen could safely and deliberately be imported and released into a country to control a weed of agricultural importance. All three projects were successful in the sense that Puccinia chondrillina was released into Australia to control rush skeleton weed and was released later into the United States as well, and that Colletotrichum gloeosporioides f.sp. aeschynomene and Phytophthora palmivora were later both marketed for the specific purpose of controlling specific weed species.







Ecological Interactions And Biological Control


Book Description

Recent interest in nonchemical methods of pest control has brought renewed attention to the biological control of plant pests in the fields of entomology, plant pathology, and weed science. Ecological Interactions and Biological Control addresses issues of theory and practice common to all three fields. Focusing on systems rather than on individual