Potential role of plant pathogens in declines of submersed macrophytes

Abstract

The role of plant disease in determining distribution and abundance of submersed aquatic macrophytes has rarely been studied. The most definitive case of a microbial agent causing decline of a submersed aquatic plant is the wasting disease of eelgrass, Zostera marina L., which is caused by a marine slime mold. Plant pathogens have also been suggested as a potential cause of Myriophyllum spicatum declines in Chesapeake Bay and in Madison, WI, area lakes. Attempts to identify pathogens for use in biological control of submersed plants have yielded several promising microorganisms, but much effort has been expended on relatively weak pathogens. More attention needs to be given to conditions under which pathogens are evaluated, since characteristics of the chemical and physical environment and of the host population itself may determine the amount of disease which occurs. In the near future, biocontrol efforts may benefit from expected changes in U.S. Department of Agriculture regulations which will allow importation of host-specific pathogens of introduced aquatic plant species collected from the native ranges of the plants. © 1994 Taylor and Francis Group, LLC.