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Title: Evaluation of a formulation of Cercospora rodmanii for infectivity and pathogenicity of waterhyacinth
Authors: Theriot, Edwin A.
Theriot, Russell F.
Sanders, Dana R., Sr.
Keywords: Aquatic plant control
Aquatic plants
Aquatic weeds
Management methods
Biological control
Cercospora rodmanii
Pathogenic fungi
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-81-5
Abstract: As a part of a Large-Scale Operations Management Test (LSOMT) of insects and pathogens for the control of waterhyacinth in Louisiana, a formulation of the fungal pathogen Cercospora rodmanii was preliminarily evaluated to determine application rates required to achieve adequate infection of waterhyacinth under environmental conditions normally found in Louisiana. In a spring study, a c. rodmanii formulation containing 1 x 10^6 viable propagules per gram was applied to test tanks at rates of 0, 5, 10, and 20 g/m^2. After 6 weeks, it was concluded that a treatment rate of 5 x 10^6 viable propagules per square metre provides adequate infection of waterhyacinth in a spring application. In a fall study, treatment rates of 0, 1, 2.5, and 10 g/m^2 of the C. rodmanii formulation containing 4 x 10^6 viable propagules per gram were applied to replicated test tanks. After 6 weeks, all tanks that received C. rodmanii were infected by the fungus, but there were no significant differences in the level of infection among C. rodmanii treatments. Therefore, a rate of 4 x 10^6 viable propagules per square metre was deemed sufficient for a fall application. In both studies, significant secondary infection of waterhyacinth tissues was observed on new leaves of original plants and on daughter plants. Thus, progressive pathogenesis can be expected to occur when field populations of waterhyacinth are infected by C. rodmanii. Based on the results of these studies, rates of 5 x 10^6 and 4 x 10^6 viable propagules per square metre will be used for large-scale applications of C. rodmanii in spring and fall tests, respectively.
Description: Technical Report
Gov't Doc #: Technical Report A-81-5
Rights: Approved for public release; distribution is unlimited
Appears in Collections:Technical Report

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